Polarization rotator

Abstract

Embodiments of the present disclosure relate to a polarization rotator (200A, 200B) and a communication device (2800) comprising the polarization rotator (2802). In an aspect, the polarization rotator (200A, 200B) comprises a first portion (202, 208); and a second portion (204, 210) connected to the first portion (202, 208), wherein the first portion (202, 208) and the second portion (204, 210) are of (i) a first shape (406) with a contour of a spline curve or (ii) a second shape (1732) formed by combining a partial rectangle (1740) and a plurality of partial circles (1734, 1736, 1738) with different radii. The polarization rotator is more effective, and can allow for better bandwidth control and significantly improved impedance matching.

Description

FIELD

[0001] Various example embodiments generally relate to the field of communications and in particular, to a polarization rotator and a communication device comprising the polarization rotator.BACKGROUND

[0002] The architecture of the next generation backhaul networks should be capable of providing the increased demand for data rates required by emerging applications such as autonomous vehicles, advanced industrial automation and control systems, heavy cloud computing, cutting edge artificial intelligence, holographic transmissions, and cryptography. The active pursuit of 6th generation (6G) mobile communication systems worldwide is fully justified by the multitude of advantages that it promises to offer. However, to build this next generation network, it is crucial to develop all the necessary radio frequency (RF) network components.

[0003] Therefore, several projects focused on developing these components have already started. One of the projects aims to evaluate the feasibility of satellite links operating in the millimeter wave band (D-Band). This involves conducting a comprehensive review of currently available RF technology in the D-Band, as well as analyzing the potential for 6G satellite systems. In the telecommunications industry, RF modules, including transceivers, filters, amplifiers, and antennas operating in the D-Band are experimentally characterized. These modules are specifically designed to enable 6G technologies. Another project is aimed at identifying the key technical enablers for the evolution from gigabits per second (Gbps) in 5G to terabits per second (Tbps) in 6G communications.SUMMARY

[0004] In general, example embodiments of the present disclosure provide a polarization rotator and a communication device comprising the polarization rotator. For example, the polarization rotator provided by the example embodiments of the present disclosure can allow for better bandwidth control, easy machining and improved impedance matching.

[0005] In a first aspect, there is provided a polarization rotator. The polarization rotator may comprise a first portion; and a second portion connected to the first portion, wherein the first portion and the second portion are of (i) a first shape with a contour of a spline curve or (ii) a second shape formed by combining a partial rectangle and a plurality of partial circles with different radii.

[0006] In some example embodiments, the first portion and the second portion may be of the first shape and may be rotationally symmetric around a vertical plane with each other.

[0007] In some example embodiments, the spline curve may be a closed curve defined by a plurality of sub-functions, and a sub-function among the plurality of sub-functions may define a segment of the spline curve.

[0008] In some example embodiments, the spline curve may be determined by interpolating a plurality of second-degree polynomial functions based on a plurality of points. In some example embodiments, a second-degree polynomial function among the plurality of second-degree polynomial functions may be defined by a plurality of coefficients and a plurality of positive integer power variables.

[0009] In some example embodiments, the spline curve may go through the plurality of points or is within a polygon determined based on the plurality of points.

[0010] In some example embodiments, the number of the plurality of points for determining the spline curve may be comprised between fifteen and twenty-five.

[0011] In some example embodiments, the first portion and the second portion may have the second shape and are axially symmetric with each other.

[0012] In some example embodiments, the different radii may progressively decrease in a direction away from the partial rectangle.

[0013] In some example embodiments, the number of the plurality of partial circles may be three.

[0014] In some example embodiments, a first distance may be between a first center of a first partial circle among the plurality of partial circles and an edge of the partial rectangle. In some example embodiments, a second distance may be between a second center of a second partial circle among the plurality of partial circles and the first center. In some example embodiments, a third distance may be between a third center of a third partial circle among the plurality of partial circles and the second center. In some example embodiments, the first distance, the second distance, and the third distance may be the same or different.

[0015] In some example embodiments, centers of the partial rectangle and the plurality of partial circles may be aligned following a horizontal axis such that there is no displacement between the centers of the partial rectangle and the plurality of partial circles in a vertical axis.

[0016] In some example embodiments, the partial rectangle may have rounded corners. In some example embodiments, a length and a width of a complete rectangle corresponding to the partial rectangle may be the same or different.

[0017] In some example embodiments, a first radius of the first partial circle may be around 0.55 millimeters. In some example embodiments, a second radius of the second partial circle may be around 0.28 millimeters. In some example embodiments, a third radius of the third partial circle may be around 0.17 millimeters.

[0018] In some example embodiments, the first distance may be around 0.62 millimeters. In some example embodiments, the second distance may be around 0.34 millimeters. In some example embodiments, the third distance may be around 0.20 millimeters. In some example embodiments, the length of the complete rectangle may be around 1.15 millimeters. In some example embodiments, the width of the complete rectangle may be around 0.43 millimeters.

[0019] In some example embodiments, the polarization rotator may comprise a waveguide portion connecting the first portion and the second portion.

[0020] In some example embodiments, the first portion and the second portion may be of the first shape, and a thickness of the polarization rotator may be around 0.3 millimeters.

[0021] In some example embodiments, the first portion and the second portion may be of the second shape, and the thickness of the polarization rotator may be around 0.52 millimeters.

[0022] In some example embodiments, each of the first portion and the second portion may have a metal housing. In some example embodiments, an interior of the metal housing may be a vacuum or air.

[0023] In some example embodiments, the polarization rotator may be operated in a millimeter wave band.

[0024] In some example embodiments, an operational bandwidth of the polarization rotator may be from around 125 gigahertz (GHz) to around 180 GHz.

[0025] In some example embodiments, the polarization rotator may rotate a polarization angle of an electromagnetic wave by forty-five degrees at an output relative to an initial polarization angle at an input of the polarization rotator.

[0026] In some example embodiments, the polarization rotator is a one-piece machined part.

[0027] In a second aspect, there is provided a communication device. The communication device may comprise the polarization rotator.

[0028] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Some example embodiments will now be described with reference to the accompanying drawings, in which: FIGS. 1A-1B illustrate some example rotators related to some example embodiments of the present disclosure may be implemented; FIGS. 1C-1F illustrate some example use cases related to some example embodiments of the present disclosure may be implemented; FIGS. 2A-2B illustrate example polarization rotators in accordance with some example embodiments of the present disclosure; FIG. 3A-3B illustrate example spline curves in accordance with some example embodiments of the present disclosure; FIGS. 4A-4E illustrate example spline functions and rotator structures in accordance with some example embodiments of the present disclosure; FIGS. 5A-5B illustrate example inner and outer spline profiles in accordance with some example embodiments of the present disclosure; FIG. 6 illustrates example an electromagnetic propagation simulation including the spline shape rotator in accordance with some example embodiments of the present disclosure; FIGS. 7A-7E illustrate a spline curve shaped electric field electromagnetic simulation in accordance with some example embodiments of the present disclosure; FIGS. 8A-8B illustrate an electrical field (E-Field) simulation rotation at 180 GHz performed by the spline shape rotator in accordance with some example embodiments of the present disclosure; FIG. 9 illustrates a return loss |S1(1),1(1)| simulation in the D-Band in accordance with some example embodiments of the present disclosure; FIG. 10 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the D-Band in accordance with some example embodiments of the present disclosure; FIGS. 11A-11B illustrate the variation of the return loss with the rotator angular deviation in accordance with some example embodiments of the present disclosure; FIG. 12 illustrates a return loss simulation (co-polarization) in the E-Band in accordance with some example embodiments of the present disclosure; FIG. 13 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the E-Band in accordance with some example embodiments of the present disclosure; FIG. 14 illustrates a return loss simulation (co-polarization) in the 5.5 GHz - 8.5 GHz frequency band in accordance with some example embodiments of the present disclosure; FIG. 15 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in accordance with some example embodiments of the present disclosure; FIG. 16 illustrates a spline shape rotator machined part in accordance with some example embodiments of the present disclosure; FIGS. 17A-17B illustrate example multi-section rotator architectures in accordance with some example embodiments of the present disclosure; FIGS. 18A-18D illustrate example different views of the multi-section rotator in accordance with some example embodiments of the present disclosure; FIGS. 19A-19E illustrate a multi-section rotator E-Field simulation co-polarization mode in accordance with some example embodiments of the present disclosure; FIGS. 20A-20B illustrate a physical rotation of the vertical polarization in accordance with some example embodiments of the present disclosure; FIG. 21 illustrates a return loss simulation (co-polarization) in the D-Band in accordance with some example embodiments of the present disclosure; FIG. 22 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the D-Band in accordance with some example embodiments of the present disclosure; FIG. 23 illustrates a return loss simulation (co-polarization) in E-Band in accordance with some example embodiments of the present disclosure; FIG. 24 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the E-Band in accordance with some example embodiments of the present disclosure; FIG. 25 illustrates a multi-section rotator return loss simulation (co-polarization) in accordance with some example embodiments of the present disclosure; FIG. 26 illustrates a multi-section rotator transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in accordance with some example embodiments of the present disclosure; FIG. 27 illustrates a multi-section rotator machined part in accordance with some example embodiments of the present disclosure; and FIG. 28 illustrates an example communication device comprising the polarization rotator in accordance with some example embodiments of the present disclosure.

[0030] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0031] Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

[0032] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which the present disclosure belongs.

[0033] References in the present disclosure to "one embodiment," "an embodiment," "an example embodiment," and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0034] It may be understood that although the terms "first" and "second" etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "has", "having", "includes" and / or "including", when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. As used herein, "at least one of the following: " and "at least one of " and similar wording, where the list of two or more elements are joined by "and" or "or", mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0036] To obtain the requirements of ultra-high-speed communication, one promising approach is to exploit terahertz frequencies beyond 100 GHz. This allows for flexible RF transceivers or antenna arrays with multi-band and broad bandwidth capabilities. This is due to the substantially broader frequency spectrum that can be exploited in comparison to 5G. Additionally, compared with the microwave operating at traditional frequency bands, D-Band antenna beam widths are narrow, which minimizes RF interference between cells, and enables dense site deployment, and facilitates reuse of the frequency channels. One of the significant devices that will be required in 6G is a polarization rotator, as it is mandatory for many RF subsystems.

[0037] The electromagnetic (EM) waves are vector quantities characterized by both magnitude and phase. In wireless backhaul networks, these EM waves are typically linearly polarized, with polarization occurring in either the vertical or horizontal direction, or both at the same time. Thus, RF devices known as rotators are required to change the polarization angle of the wave and rotate it according to engineering requirements in the most efficient way as possible (impedance matching, transmission loss and cross polarization discrimination).

[0038] Future 6G backhaul wireless networks are expected to handle significantly larger amounts of data and provide higher data rates than the current 5G networks. One highly promising solution for operating 6G networks is the use of the D-Band, whose operational bandwidth is more than 40%, thereby enabling an increased capacity for the channel to carry data. From now on, the definition of operational bandwidth (%) is f H − f L f C × 100, where f L represents the start frequency of the operation frequency band, f H represents the end frequency and f C represents the center frequency.

[0039] Therefore, there is a need to propose a solution for the design of broadband RF rotators operating in extreme high frequencies, with a special focus on the D-Band to enable 6G networks. The embodiments of the present disclosure provide a more effective polarization rotator. For example, the polarization rotator can change the polarization angle of a linearly polarized electromagnetic wave by a device operating in high frequency band and broad band, focused on D-Band for future 6G applications, and thus can allow for better bandwidth control and significantly improved impedance matching.

[0040] For illustrative purposes, principles and example embodiments of the present disclosure of a polarization rotator will be described below with reference to FIG. 1A- FIG. 27. However, it is to be noted that these embodiments are given to enable the skilled in the art to understand inventive concepts of the present disclosure and implement the solution as proposed herein, and not intended to limit scope of the present application in any way.

[0041] Reference is made to FIGS. 1A-1B, which illustrate some example rotators related to some example embodiments of the present disclosure may be implemented. As illustrated in FIGS. 1A and 1B, the rotator 102 and the rotator 104 are broadband polarization rotators that operate in the millimeter wave band. The rotator 102 is symmetric, and the rotator 104 is symmetric, too. The rotator 102 and the rotator 104 are capable of rotating both vertical and horizontal polarized waves with the same performance, while maintaining a high level of cross polarization discrimination. This feature is significant for cross polarization interference cancellation (XPIC) in backhaul applications.

[0042] Reference is made to FIGS. 1C-1F, which illustrate some example use cases related to some example embodiments of the present disclosure may be implemented. It is to be understood that the following use cases will focus on the vertical polarization, however, the same level of performance when operating with horizontal polarization.

[0043] As shown in FIG. 1C, a use case 100C is a use case for a polarization rotator, and it arises when there is a need to rotate the polarization between one antenna and one outdoor unit (ODU). In the use case 100C, a vertically polarized wave is received by the antenna, and it may be transmitted to the ODU having a specific angle of polarization. Polarization rotation before entering the ODU may be required for various reasons, such as mechanical issues where the ODU is not installed symmetrically relative to the antenna, or when its input rectangular waveguide is not positioned linearly. Another reason for polarization rotation is to address clearance issues. Regardless of the technical reason for using a polarization rotator, it is crucial to maintain a low level of cross polarization (horizontal polarization) to enhance the cross polarization discrimination property.

[0044] In some cases, the ODU may need to be installed in a specific rotated orientation to avoid hitting the tower or causing issues with the RF cables connected to the ODU. In this case, a polarization rotator can be used to rotate the polarization before it enters the ODU, allowing for the ODU to be installed in the desired orientation while maintaining the correct polarization.

[0045] As shown in FIG. 1D, a use case 100D shows another application of a RF rotator. In the use case 100D, the RF rotator is integrated into flat or planar slot waveguide antennas. This type of antenna has raised significant interest in recent years due to its low profile, light weight, and high gain. However, slot array antennas often experience the problem of grating lobes. To address this issue, one solution is to rotate the polarization at a 45-degree angle. As this type of antenna is expected to be used in the D-Band for 6G, there will be a demand for high-performance and easily manufacturable polarization rotators.

[0046] An RF rotator is required in a large variety of radio frequency components. In a transmitter / receiver (transceiver module) widely used in ODUs, it may be necessary to rotate the wave polarization at the input and / or output of the power chain processing. As shown in FIG. 1E, a use case 100E shows that the vertical polarization has been rotated before coming into the ODU, and the transceiver must rearrange it again vertically before doing some RF processing. As shown in FIG. 1F, the use case 100F shows that an orthomode transducer (OMT) splits / combines two orthogonal polarizations into the same physical path, for instance a waveguide. In some cases, to optimize the OMT design is mandatory to rotate one of the polarizations. This may be justified by various factors such as the need for compactness, clearance, machining issues, RF performance, or cost reduction because the polarization rotation enables the transition from the wider waveguide section to the thinner one, and vice versa, providing more flexibility in the OMT design.

[0047] From the discussion with reference to FIGS. 1A-1F, it can be seen that the problems of the D-Band and broadband polarization rotator may be rotating the angle of polarization of one linear EM wave being symmetric in the operation mode (vertical and horizontal). Therefore, generally, the problem that the present disclosure solves may be changing the polarization angle of a linearly polarized electromagnetic wave by a device operating in high frequency band and broad band, focused on D-Band for future 6G applications. In some example embodiments, the RF device may have an original shape to integrate easy manufacturing processes with machining tolerances and should be a single part to avoid complicated assembly procedures, thus maintaining high compactness. In some example embodiments, the RF device may maintain excellent radio frequency properties such as return loss, transmission loss, and cross polarization discrimination.

[0048] Additionally, the solution of the present disclosure can achieve the best RF key performance figures such as return loss (RL), transmission loss, and cross polarization discrimination. Further, the solution of the present disclosure can be manufacturable as a single part with low thickness to avoid complicated assembly procedures and the generation of undesired resonant frequencies, which may cause RF transmission drops due to the assembly of multiple parts or excessively sharp shapes. This is because even a small deviation from the desired geometry during the manufacturing process can lead to a significant degradation in the RF performance of the rotator. Therefore, the present disclosure is carefully designed to minimize sensitivity to tolerance errors and ensure robust and reliable operation, especially in the D-Band where the wavelength is very small.

[0049] Reference is made to FIGS. 2A-2B, which illustrate example polarization rotators in accordance with some example embodiments of the present disclosure. As shown in FIG. 2A, the polarization rotator 200A comprises a portion 202 and a portion 204. The portion 202 is connected to the portion 204. In some example embodiments, the portion 202 and the portion 204 may be connected using a section 206. In some example embodiments, the section 206 may be a waveguide portion.

[0050] The portion 202 and the portion 206 are of a first shape with a contour of a spline curve. In some example embodiments, each of the portion 202 and the portion 204 may have a metal housing. The interior of the metal housing may be a vacuum or air.

[0051] In some example embodiments, the polarization rotator may be operated in a millimeter wave band. The operational bandwidth of the polarization rotator may be from around 125 GHz to around 180 GHz.

[0052] In some example embodiments, the contour (or the profile) of the spline curve may be modeled through interpolation of polynomial functions. The polynomial function may comprise coefficients and positive integer power variables. The combination of these polynomial functions may generate a wide range of possible coordinates, resulting in an extensive number of potential profiles. These profiles may be subsequently optimized using mathematical algorithms to ensure that each magnitude and phase component is best suited for impedance matching across the entire frequency band. Due to the large number of permutations available, the inherent property of the solution can allow for a balanced input / output impedance matching. The details of the spline curve and its modeling will be described with reference to FIGS. 3-16, and thus they will not be discussed herein.

[0053] As shown in FIG. 2B, the polarization rotator 200B comprises a portion 208 and a portion 210. The portion 208 is connected to the portion 210. In some example embodiments, the portion 208 and the portion 210 may be connected using a small and symmetric waveguide section 212.

[0054] The portion 208 and the portion 210 are of a second shape formed by combining a partial rectangle and a plurality of partial circles with different radii. In some example embodiments, the contour (profile) of the second shape is referred to as the multi-section.

[0055] The approach for determining the multi-section may involve generating multiple resonant frequencies, which when combined, may create a broad operational bandwidth similar to a multi carrier frequency spectrum. The selected shape may comprise several circles with different radii. With properly dimensioned, these circles resonate in parallel and are spaced in the frequency domain. The resulting effect is a broad operational bandwidth achieved with an extremely simple profile design. The details of the multi-section and its modeling will be described with reference to FIGS. 17-29, and thus they will not be discussed herein.

[0056] By implementing the embodiments of FIGS. 2A-2B, the polarization rotator is more effective, and thus it can allow for better bandwidth control and significantly improved impedance matching. In some example embodiments, the polarization rotator may be intended for use in the millimeter wave band, particularly in D-Band, which requires a broad frequency range, up to 45% of operational bandwidth. Additionally, the polarization rotator may be designed for ease of manufacturing by avoiding complex profiles and opting for single part designs.

[0057] It is to be understood that both spline shape and multi-section shape are simple and effective in solving the inherently complex manufacturing process required for RF devices operating at frequencies around 150 GHz and even higher frequencies. It may be indicated that the performance of the spline shape and multi-section rotators has been evaluated using RF simulations carried out with the time domain solver of CST microwave studio. This electromagnetic simulation software can provide highly accurate simulation results that validate the solutions of the presented disclosure.

[0058] Reference is made to FIGS. 3A-3B, which illustrate example spline curves in accordance with some example embodiments of the present disclosure. The spline curve may be a closed curve defined by a plurality of sub-functions, and a sub-function among the plurality of sub-functions defines a segment of the spline curve. In some example embodiments, the spline curve may be determined by interpolating a plurality of second-degree polynomial functions based on a plurality of points. In some example embodiments, a second-degree polynomial function among the plurality of second-degree polynomial functions may be defined by a plurality of coefficients and a plurality of positive integer power variables.

[0059] For example, as shown in FIG. 3A, points 302, 304 and 306 are three fixed points. The spline curve may be a function or curve that comprise multiple sub-functions where each sub-function applies to a different interval in the function domain. For example, the curves 308 and 310 may be determined by polynomials, such as two quadratic polynomials of the form y = a 2 x 2< + a 1 x + a 0 , where a 2 , a 1 and a 0 are constants. The spline curves can take on different forms, as shown in the curves 312 and 314. The interpolation with the quadratic polynomial may be done between the coordinates or knots. As shown in FIG. 3B, a cross 320 represents a knot. A quadratic polynomial 322 may be determined by these knots.

[0060] Depending on the values assigned to the coefficients (such as a 2 , a 1 and a 0 ), the spline curve can take too many different shapes. This may have significant implications as it provides a large degree of freedom in terms of design diversity.

[0061] Impedance matching in a broad frequency band can be a challenging task due to the need to handle to many multiple frequency components. Electromagnetic waves may react or are dependent obviously to the wavelength and on this, in the physical dimensions of the RF component. Even if a radio frequency device can be perfectly adapted to a particular frequency band, its RF performance will be degraded outside of the band due to their inappropriate dimensions.

[0062] The wide range of possible permutations of the control coefficients of the polynomial curves will try to fit at best with the proper impedance matching properties over the frequency domain. Therefore, the spline curve approach aims to utilize its inherent large degree of design freedom to solve the broadband impedance matching problem, seeking an extremely smooth variation over the entire targeted frequency band.

[0063] Reference is made to FIGS. 4A-4E, which illustrate example spline function and rotator structure in accordance with some example embodiments of the present disclosure. The spline curve may go through the plurality of points or is within a polygon determined based on the plurality of points. In some example embodiments, the number of the plurality of points for determining the spline curve may be comprised between fifteen and twenty-five. For example, as shown in FIG. 4A, an optimization algorithm may be used to establish the number of points (such as points 401, 402, 403 and 404 and so on) for the spline curve, which was determined to be 15-25 through an iterative process. It is to be understood that the numbers of points and the numbers of iterative process are only for illustrative purpose without any limitations.

[0064] The goal of the RF specification may be to optimize the return loss value, transmission loss and cross polarization discrimination over the broadest possible frequency band. In some example embodiments, the portion 202 and the portion 204 may be of the first shape and are rotationally symmetric around a vertical plane with each other. For example, once the spline curve is defined, the rotator architecture can be obtained by mirroring the shape about the vertical axis and then rotating the mirrored shape about the horizontal plane. For example, as shown in FIG. 4B, the portion 406 can be obtained by mirroring the portion 406 about the axis 408, and then rotating the mirrored portion 416 about the axis 410.

[0065] The main part of the spline shaped rotator may be defined by the former description of FIG. 3. However, to create an actual RF rotator, a non-discontinuous shape / profile should be obtained. Thus, the two symmetric spline shapes are connected using a small, symmetric waveguide section, as shown by part 412 in FIG. 4C. The part 412 is required to maintain an electrical continuity.

[0066] The resulting smoothed shape may be then used to fabricate the physical RF rotator (as shown in FIG. 4D and FIG. 4E) having lower thickness and an easier manufacturing than the traditional RF rotators. The continuous and original profile of the spline shape rotator may be an important feature that prevents the occurrence of undesired resonant frequencies due to the wrong combination of steps, section changes, or different parts inside a waveguide. One advantage is also its small thickness. For example, the thickness 414 in FIG. 4E may be only 0.3 millimeters after optimization in D-Band.

[0067] Reference is made to FIGS. 5A-5B, which illustrate example inner and outer spline profiles in accordance with some example embodiments of the present disclosure. FIG. 5 compares the inner and outer spline profiles. In the outer profile the spline smoothly goes through all points and touching them. In contrast, in the inner spline profile, the spline stays within the cage formed by the points. The advantage of the spline rotator is that the freedom degree goes further than the number of coefficients. The explanation is associated with the interpolation property of this type of curve. Once the coefficients are defined, the interpolation can be carried out in two different ways, following the inner profile, or choosing the outer profile. This means that a single spline shape design can be optimized for better RF performance or to avoid machining issues by following either profile.

[0068] As shown in FIG. 5A, a curve 502 shows an outer spline and a curve 504 shows an inner spline. The difference may not seem too significant but when the two profiles are directly overlapped (as shown in FIG. 5B), the design freedom becomes much clearer. By using the inner and outer spline profiles as a guide for the RF design, the actual machined profile can be expected to fall statistically within those limits. This may help to minimize the potential RF deterioration that may occur due to machining deviations during the manufacturing process. This can be an advantage in D-Band applications where the wavelength at 180 GHz is 1.67 millimeters and very sensitive to machining issues.

[0069] Reference is made to FIG. 6, which illustrates example electromagnetic propagation simulation including the spline shape rotator in accordance with some example embodiments of the present disclosure. The polarization rotator may rotate a polarization angle of an electromagnetic wave by forty-five degrees at an output relative to an initial polarization angle at an input of the polarization rotator. In some example embodiments, the polarization rotator may be a one-piece machined part.

[0070] For example, the spline shape rotator architecture has been defined in FIG. 5. The simulation may create two orthogonal and linear polarizations. That is, one vertically polarized wave is following the y-axis, represented by an arrow 602 coming into the circular waveguide. One horizontally polarized wave is following the x-axis and defined by an arrow 604. As the polarizations are orthogonal, they are out of phase 90 degrees. The study case is the rotation of the vertical polarization from 0 degree (y-axis) to 45 degrees towards the positive x-axis. The spline shape rotator is placed at 22.5 degrees as transition rotation angle.

[0071] As previously mentioned, one of the objectives of the present disclosure is to provide a technical solution that achieves high performance for future backhaul networks, focused on the D-Band. Consequently, the simulation of the E-field of the spline shaped rotator at 125 GHz (start frequency) and 180 GHz (end frequency) is shown in FIG. 7A-7E. The simulations operate in co-polarization mode and in cross polarization mode. All simulations exposed herein have been done with the time domain solver integrated by CST microwave studio.

[0072] Reference is made to FIGS. 7A-7E, which illustrate a spline curve shaped electric field electromagnetic simulation in accordance with some example embodiments of the present disclosure. For the D-Band (36%) simulation, in mono scale color ramp, the inner arrows (such as arrows 702 and 704) represent the simulated vertical direction of the electric field, which is defined by the larger arrow 706. This can ensure that the vectors are correctly oriented, and the energy transfer is proper. Additionally, the required broadband operation is clearly achieved as the simulation demonstrates uniform performance on the far spaced frequency samples (125 GHz and 180 GHz). More frequency samples can be shown but no undesired polarization rotation has been observed in any case.

[0073] Regarding the cross polarization mode in FIG. 7C, the inner arrows (such as arrows 708 and 710) are perfectly 180 degrees out of phase, as indicated by the two larger arrows (such as arrows 712 and 714), which will cancel the energy transmission providing high values of cross polarization discrimination.

[0074] As shown in FIG. 7E, the broadband performance in the D-Band can be also proven by the vector cancellation occurring over a broad range of frequency samples, similar to the co-polarization operation. Another proof of the present disclosure is the absence of energy across the center of the rotator which is consistent with the principle of operation. In FIG. 7E, the solid arrow (such as arrows 718 or 720) follows the angle of the energy null across the center which fits correctly with 22.5 degrees at 180 GHz (the scale was changed to improve the visual analysis).

[0075] Reference is made to FIGS. 8A-8B, which illustrate an E-Field simulation rotation at 180 GHz performed by the spline shape rotator. As shown in FIG. 8A, it provides a visual representation of the polarization rotation of a polarized wave at 180 GHz, assuming a rotation from 0 degree to 45 degrees in the vertical polarization. In FIG. 8A, it describes that a vertically polarized wave is introduced into the present disclosure through a rectangular waveguide. In FIG. 8B, the polarization is rotated by 45 degrees, with all the energy well oriented at the required angle. This is achieved once the rotator has completed the transition from 0 degrees to 22.5 degrees, before finishing at 45 degrees. S-parameter simulations are also conducted to evaluate the performance of the present disclosure in the D-Band, which is defined as ranging from 125 GHz to 180 GHz which corresponds to an operational bandwidth of 36%.

[0076] Reference is made to FIG. 9, which illustrates return loss |S1(1),1(1)| simulation 900 (co-polarization) in the D-Band in accordance with some example embodiments of the present disclosure. The return loss simulation (|S11|) is operating in co-polarization mode. That is, a vertical polarization relative to vertical polarization. The RL value of the spline shape rotator is better than 40 dB over the entire frequency band demonstrating outstanding performance for its use in applications where high precision machining is required. This is a first optimization of the present disclosure, it is believed that an improvement of around 10 GHz can be achieved, resulting in an operational bandwidth increase of up to 40%. This would meet the required specifications for 6G specifications.

[0077] Reference is made to FIG. 10, which illustrates transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 1000 where (1) indicates the vertical polarization or first mode and (2) indicates horizontal polarization or second mode in the D-Band in accordance with some example embodiments of the present disclosure. The simulated transmission loss, |S2(1),1(1)| parameter that defines the power ratio between output 2 and the input 1 of the same propagation mode (1) vertical, is almost 0 dB over the D-Band which proves again the correct RF operation of the spline shape rotator. With respect to cross-polarization, the value is extremely high, at around 100 dB, which will provide an exceptional level of isolation between polarizations. It is illustrated by the |S2(2),1(1)| parameter, the power ratio between the output 2 and the input 1 of the mode 2 (horizontal) over the mode 1 (vertical). To facilitate understanding, the mode 1 is referred to as the vertical polarization, and mode 2 is referred to as the horizontal polarization, as defined in FIG. 6.

[0078] It is to be understood that the spline shape rotator effectively prevents the wave for spinning out of control across the frequency band because no drop of energy (transmission loss) is predicted by the simulation. If there were any transmission loss at any frequency point, it would indicate that the angle of polarization of the output wave does not match the angular rotation that the rotator is designed to produce.

[0079] The following Table 1 provides the calculated values (in millimeters) of the spline curve coefficients and thickness T hs of the previous simulation results following the architecture of FIGS. 4A-4E. Table 1. Spline line coefficients of the rotator operating in D-Band.x 0 ,y 0 0.52,0.91x 1 ,y 1 0.37,0.89x 2 ,y 2 0.29,0.80x 3, y 3 0.24,0.69x 4 ,y 4 0.10,0.64x 5 ,y 5 0,0.53x 6 ,y 6 0.28,0.35x 7 ,y 7 0.33,0.16x 8 ,y 8 0.33, -0.17x 9 ,y 9 0.40, -0.34x 10 ,y 10 0.50, -0.39x 11 ,y 11 0.73, -0.42x 12 ,y 12 0.96, -0.32x 13 ,y 13 0.96,0x 14 ,y 14 0.86,0x 15 ,y 15 0.82,0.31x 16 ,y 16 0.69,0.50x 17 ,y 17 0.62,0.71x 18, y 18 0.63,0.83T hs 0.3 where point (x 0 ,y 0 ) may represent point 401 as an example, point (x 18 ,y 18 ) may represent point 404 as an example. T hs may represent the thickness 414 as an example.

[0080] Reduced thickness should be noted, 0.3 mm, resulting in only λ 8 at 125 GHz (bigger wavelength case). This thickness is lower compared with the traditional rotators and very attractive for extreme compactness requirements.

[0081] One of the objectives of the spline rotator is to achieve effective polarization rotation, and one of the frequent issues causing problems is the angular misalignment between the rotator and the input / output waveguides. This problem is particularly critical in millimeter wave applications, as a small deviation of the angular position becomes significantly large in relation to the operation wavelength.

[0082] Reference is made to FIGS. 11A-11B, which illustrate the variation of the return loss with rotator angular deviation in accordance with some example embodiments of the present disclosure. As shown in FIG. 11A, it shows the rotator angular deviation, and FIG. 11B shows the return loss and transmission loss parametric simulation of the angular sensitivity (in degrees). The RL (|S1(1),1(1)|) and transmission loss (|S2(1),1(1)|) show correct performance in the entire D-Band even when angular deviations up to 8 degrees from the nominal are applied.

[0083] Reference is made to FIG. 12, which illustrates a return loss simulation 1200 (co-polarization) in the E-Band in accordance with some example embodiments of the present disclosure. For the E-Band (25%) simulation, as shown in FIG. 12, the spline shape rotator has been also examined in the other millimeter wave band of interest, the E-Band (71 GHz - 86 GHz) with the aim of achieving an operational bandwidth of 25% (70 GHz - 90 GHz). The spline rotator as proposed can also operate correctly in this millimeter wave band, as the RL value is more than 35 dB.

[0084] Reference is made to FIG. 13, which illustrates transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 1300 in the E-Band in accordance with some example embodiments of the present disclosure. As shown in FIG. 13, the dashed line 1302 represents the transmission loss, and the dotted line 1304 represents the cross polarization. Similar to the D-Band, the successful operation of the present disclosure is demonstrated in the E-Band, with a transmission loss value near 0 dB and an isolation ratio between the two polarizations better than 90 dB across the entire frequency band.

[0085] Reference is made to FIG. 14, which illustrates return loss simulation 1400 (co-polarization) in the 5.5 GHz - 8.5 GHz frequency band in accordance with some example embodiments of the present disclosure. for the 5.5 GHz - 8.5 GHz (43%) simulation, to demonstrate the quality of the present disclosure, the present disclosure has pushed the limits of the spline shape rotator to achieve extremely high operational bandwidths. As such, RF simulations were carried out from 5.5 GHz up to 8.5 GHz, corresponding to an operational bandwidth of 43%. It is to be noted that this covers two distinct licensed backhaul frequency bands: 5.925 GHz - 7.125 GHz and 7.125 GHz - 8.5 GHz. FIG. 14 shows a RL value better than 40 dB on the entire frequency band.

[0086] Reference is made to FIG. 15, which illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 1500 in accordance with some example embodiments of the present disclosure. To confirm the proper operation of the spline shape rotator, both the transmission loss (dashed line 1502) and cross polarization discrimination (dotted line 1504) values were again analyzed. The results demonstrated excellent performance over nearly 45% of the operational bandwidth, which further validates the operating principle of the present disclosure. One point is that the intrinsic broadband performance of the present disclosure can enable adequate coverage of the unlicensed Backhaul band 5.725 GHz - 5.85 GHz, which further demonstrates the versatility of the present disclosure.

[0087] Reference is made to FIG. 16, which illustrates a spline shape rotator machined part in accordance with some example embodiments of the present disclosure. A view 1602 shows a front view. A view 1604 shows a side view. A view 1606 shows a perspective view. The spline shape rotator is illustrated in FIG. 16 as a machined part, and thus its simplicity is exceptional.

[0088] Reference is made to FIGS. 17A-17B, which illustrate example multi-section rotator architectures in accordance with some example embodiments of the present disclosure. The principle of the multi-section rotator is founded on the operation of multiple resonant frequencies working in parallel and spaced out in the frequency domain, creating a broad operational bandwidth. An approach to force several and spaced resonant frequency samples is to use a combination of various circles defined by distinct diameter, much like the design of circular waveguides used for different frequency bands.

[0089] In FIG. 17A, the architecture of the multi-section rotator is shown. The multi-section rotator may comprise a rectangular body 1740 and three circles 1734, 1736 and 1738 with progressively decreasing radii. The center of the leftmost edge of the rectangular body 1740 is center 1702. In some example embodiments, the length 1716 of the rectangular body 1710 may be around 1.15 millimeters, and the width 1742 of the rectangular body 1740 may be around 0.43 millimeters.

[0090] The center of first circle 1734 is center 1704. The radius of first circle 1734 is radius 1722. The center of second circle 1736 is center 1706. The radius of second circle 1736 is radius 1720. The center of third circle 1738 is center 1708. The radius of third circle 1738 is radius 1718. In some embodiments, the radius 1722 may be around 0.55 millimeters. The radius 1720 may be around 0.28 millimeters. The radius 1718 may be around 0.17 millimeters.

[0091] The radii 1718, 1720 and 1722 may not be identical. The first circle 1734, the second circle 1736 and the third circle 1738 may be moved further away from the center 1702. For example, Taking the centers 1704, 1706 and 1708 as references, the multi-section rotator may be also modeled by the horizontal displacement of the three circles 1734, 1736 and 1738 relative to the center 1702. For example, the first circle 1734 may be moved by a distance 1714 away from the center 1702. The second circle 1736 is moved by a distance 1712 away from the center 1704. The third circle 1738 may be moved by a distance 1710 away from the center 1706.

[0092] These distance parameters can be identical or distinct, and they play a significant role in determining the performance of the rotator. Regarding the vertical arrangement, the circles 1734, 1736 and 1738 are centered with respect to the rectangular body 1740. The rectangular body 1740 may be defined by the length 1716 and the width 1742. The length 1716 and the width 1742 may not have the same value.

[0093] As shown in FIG. 17B, the final outer profile of these four elements forms the half body 1732 of the multi-section rotator. Another half body is symmetric. The curve 1730 represents the outer profile of the third circle 1738. The curve 1728 represents the outer profile of the second circle 1736. The curve 1726 represents the outer profile of the first circle 1734. The curve 1724 represents the outer profile of the rectangular body 1740.

[0094] Reference is made to FIGS. 18A-18D, which illustrate example different view of the multi-section rotator in accordance with some example embodiments of the present disclosure. As shown in front view of FIG. 18A, the multi-section shape is vertically mirrored (such as half body 1802 and half body 1804) and then both half bodies 1802 and 1804 are connected by a rectangular section 1806. The rotated front view of FIG. 18B and a complete rotator perspective view of FIG. 18C are further shown in for better illustrative purpose.

[0095] Thus, the multi-section rotator is then obtained as a 3D model part (as shown in a perspective view of FIG. 18C) using the former defined profile. The thickness 1808 is shown in FIG. 18D), which is a side view of the multi-section rotator.

[0096] The multi-section rotator architecture has been defined in FIGS. 18A-18D, as in the same way that the spline curve rotator, the EM simulation of the present disclosure is carried out to evaluate its performance. The transition angle between the rotator and the input / output waveguides is again 22.5 degrees. Again, the main objective of the present disclosure is to offer a technical solution that can attain high performance for future backhaul networks, specially focused on the D-Band.

[0097] Reference is made to FIGS. 19A-19E, which illustrates a multi-section rotator E-Field simulation co-polarization mode in accordance with some example embodiments of the present disclosure. The EM simulation of the E-field of the multi-section rotator at 125 GHz and 180 GHz is depicted in FIGS. 19A-19E operating in co-polarization mode and cross polarization mode. For a D-Band (36%) simulation, the electric field in both frequency samples is properly transmitted and focused on the rotator center, following the inner arrows (such as arrows 1902 and 1904 in FIG. 19A), and directed vertically. Therefore, the multi-section architecture composed of three circles demonstrates correct RF operation.

[0098] Regarding the cross polarization mode, as shown in FIGS. 19C and 19D, the arrows cancels out against the output power because they are 180 degrees out of phase. To show more in detail this feature, in FIG. 19E, the solid arrow 1910 follows the angle of the energy null across the center which is properly 22.5 degrees at 180 GHz.

[0099] Reference is made to FIGS. 20A-20B, which illustrate the physical rotation of the vertical polarization in accordance with some example embodiments of the present disclosure. FIG. 20A shows a vertically polarized wave is introduced into the multi-section rotator through a rectangular waveguide. FIGS. 20B illustrates the output wave with the required change in its polarization angle 2002, demonstrating perfect transmission.

[0100] Reference is made to FIG. 21, which illustrates a return loss simulation 2100 (co-polarization) in the D-Band in accordance with some example embodiments of the present disclosure. FIG. 21 shows the return loss simulation in the D-Band defined from 125 GHz up to 180 GHz which corresponds to an operational bandwidth of 36%. The RL value is better than 35 dB in the entire required frequency band. With further optimization, the bandwidth could be increased approximately 10 GHz, resulting in a total operational bandwidth of 40%.

[0101] Reference is made to FIG. 22, which illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 2200 in the D-Band in accordance with some example embodiments of the present disclosure. As shown in FIG. 22, better energy transfer without power loss is demonstrated and extreme high value of polarization decoupling is observed, better than 100 dB.

[0102] The multi-section rotator has demonstrated excellent RF performance in terms of return loss, transmission loss, and cross-polarization decoupling, making it an ideal technical solution for D-Band applications. Furthermore, its exceptional margin of RF compliance and high operational bandwidth provide compensation for any machining deviation.

[0103] The following Table 2 shows the calculated dimensions (in millimeters) of the former D-Band multi-section rotator. Table 2 Dimensions of the broadband multi-section rotator in D-bandr 1,2,3 Value [mm]d 1,2,3 Value [mm]l 1,2 Value [mm]T hms r 1 0.55d 1 0.20l 1 0.430.52 mmr 2 0.28d 2 0.34l 2 1.15r 3 0.17d 3 0.62 where r1 represents radius 1718, r2 represents radius 1720, r3 represents radius 1722, d1 represents distance 1714, d2 represents distance 1712, d3 represents distance 1710, l1 represents width 1742, l2 represents length 1716, and T hms represents thickness 1808.

[0104] Even though the thickness is greater than that of the spline shape rotator, it still remains relatively small (0.22λ at 125 GHz, λ represents wave length), compared again with the traditional solutions. The simulated values are approximately consistent with resonant frequency multiples of λ / 2 directly decreasing with the increased frequency, with values of approximately λ / 4 at 125 GHz, λ / 6 at 155 GHz, and λ / 8 at 185 GHz. One explanation is that the former d 1 , d 2 and d 3 horizontal shifts must impact the exact resonant frequencies, and this may be considered during the design phase.

[0105] Reference is made to FIGS. 23 and 24. FIG. 23 illustrates a return loss simulation 2300 (co-polarization) in E-Band in accordance with some example embodiments of the present disclosure. FIG. 24 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2), 1(1)| simulation 2400 in the E-Band in accordance with some example embodiments of the present disclosure. Similar results in comparison with the spline shape rotator has been demonstrated, having RL better than 35 dB, cross polarization more than 100 dB and no transmission loss in 25% operational bandwidth. The multi-section rotator confirms its feasibility in the E-Band.

[0106] Reference is made to FIG. 25, which illustrates a multi-section rotator return loss simulation 2500 (co-polarization) in accordance with some example embodiments of the present disclosure. For a 5.5 GHz - 8.5 GHz (43%) simulation, the broadband multi-section rotator has proven excellent RF performances in the two most important millimeter wave bands. Additionally, it has also been tested for extreme high broadband operation, ranging from 5.5 GHz to 8.5 GHz, similar to the spline shaped rotator. The return loss simulation is shown in FIG. 25, and the RL level is better than 40 dB over 43% operational bandwidth.

[0107] Reference is made to FIG. 26, which illustrates a multi-section rotator transmission loss |S2(1), 1(1)| and cross polarization |S2(2),1(1)| simulation 2600 in accordance with some example embodiments of the present disclosure. As shown in FIG. 26, the transmission loss and cross polarization discrimination values of the multi-section rotator demonstrate the correct operation principle aimed by the present disclosure. The transmission loss, represented by the dashed line 2602, is minimal and the cross polarization discrimination, represented by the dotted line 2604, is high over nearly 45% of the operational bandwidth, indicating that there is no energy loss during polarization rotation and high cross polarization decoupling

[0108] Reference is made to FIG. 27, which illustrates multi-section rotator machined part in accordance with some example embodiments of the present disclosure. A view 2702 shows a front view. A view 2704 shows a side view. A view 2706 shows a perspective view. The spline shape rotator is illustrated in FIG. 27 as a machined part, and thus its simplicity is exceptional.

[0109] Reference is made to FIG. 28, which illustrates an example communication device 2800 comprising the polarization rotator in accordance with some example embodiments of the present disclosure. in some example embodiments, the communication device 2800 may be a transceiver. It is to be understood that this is only an example without any limitations.

[0110] The communication device 2800 may be any other devices such as a receiver or a transmitter and so on. The communication device 2800 may comprise the polarization rotator 2802 according to any embodiments discussed above. for example, the polarization rotator 2802 may be the polarization rotator 200A in FIG. 2A or the polarization rotator 200B in FIG. 2B. For brevity, the various embodiments of the polarization rotator will not be described again.

[0111] In general, the following advantages may be achieved by implementing the embodiments of the present disclosure. for example, high broadband feature (up to 45%) can be achieved. The rotator is better designed for D-Band, and it can avoid manufacturing deviations an is enhanced to prevent machining deviations due to the spline shape property. Reduced angular sensitivity can be achieved. There are no parts and / or machining intersections / sharp profiles on the exposed architectures, avoiding undesired resonant frequencies (transmission loss). The design requires only one piece to be machined, eliminating the need for assembly and simplifying the manufacturing process. Minimized thickness provides compactness solutions, especially for planar / flat antennas, OMTs and ODUs. The solution of the present disclosure to cover unlicensed backhaul frequency bands due to its broadband feature. No cross polarization issues were detected, improving the potential of dual polarization and XPIC backhaul networks. The spline curve and multi section rotators principle could be merged into one unique design to enhance even more the operational bandwidth and the RF properties.

[0112] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0113] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Examples

Embodiment Construction

[0031]Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

[0032]In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which the present disclosure belongs.

[0033]References in the present disclosure to "one embodiment," "an embodiment," "an example embodiment," and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particu...

FIELD

[0001] Various example embodiments generally relate to the field of communications and in particular, to a polarization rotator and a communication device comprising the polarization rotator.BACKGROUND

[0002] The architecture of the next generation backhaul networks should be capable of providing the increased demand for data rates required by emerging applications such as autonomous vehicles, advanced industrial automation and control systems, heavy cloud computing, cutting edge artificial intelligence, holographic transmissions, and cryptography. The active pursuit of 6th generation (6G) mobile communication systems worldwide is fully justified by the multitude of advantages that it promises to offer. However, to build this next generation network, it is crucial to develop all the necessary radio frequency (RF) network components.

[0003] Therefore, several projects focused on developing these components have already started. One of the projects aims to evaluate the feasibility of satellite links operating in the millimeter wave band (D-Band). This involves conducting a comprehensive review of currently available RF technology in the D-Band, as well as analyzing the potential for 6G satellite systems. In the telecommunications industry, RF modules, including transceivers, filters, amplifiers, and antennas operating in the D-Band are experimentally characterized. These modules are specifically designed to enable 6G technologies. Another project is aimed at identifying the key technical enablers for the evolution from gigabits per second (Gbps) in 5G to terabits per second (Tbps) in 6G communications.SUMMARY

[0004] In general, example embodiments of the present disclosure provide a polarization rotator and a communication device comprising the polarization rotator. For example, the polarization rotator provided by the example embodiments of the present disclosure can allow for better bandwidth control, easy machining and improved impedance matching.

[0005] In a first aspect, there is provided a polarization rotator. The polarization rotator may comprise a first portion; and a second portion connected to the first portion, wherein the first portion and the second portion are of (i) a first shape with a contour of a spline curve or (ii) a second shape formed by combining a partial rectangle and a plurality of partial circles with different radii.

[0006] In some example embodiments, the first portion and the second portion may be of the first shape and may be rotationally symmetric around a vertical plane with each other.

[0007] In some example embodiments, the spline curve may be a closed curve defined by a plurality of sub-functions, and a sub-function among the plurality of sub-functions may define a segment of the spline curve.

[0008] In some example embodiments, the spline curve may be determined by interpolating a plurality of second-degree polynomial functions based on a plurality of points. In some example embodiments, a second-degree polynomial function among the plurality of second-degree polynomial functions may be defined by a plurality of coefficients and a plurality of positive integer power variables.

[0009] In some example embodiments, the spline curve may go through the plurality of points or is within a polygon determined based on the plurality of points.

[0010] In some example embodiments, the number of the plurality of points for determining the spline curve may be comprised between fifteen and twenty-five.

[0011] In some example embodiments, the first portion and the second portion may have the second shape and are axially symmetric with each other.

[0012] In some example embodiments, the different radii may progressively decrease in a direction away from the partial rectangle.

[0013] In some example embodiments, the number of the plurality of partial circles may be three.

[0014] In some example embodiments, a first distance may be between a first center of a first partial circle among the plurality of partial circles and an edge of the partial rectangle. In some example embodiments, a second distance may be between a second center of a second partial circle among the plurality of partial circles and the first center. In some example embodiments, a third distance may be between a third center of a third partial circle among the plurality of partial circles and the second center. In some example embodiments, the first distance, the second distance, and the third distance may be the same or different.

[0015] In some example embodiments, centers of the partial rectangle and the plurality of partial circles may be aligned following a horizontal axis such that there is no displacement between the centers of the partial rectangle and the plurality of partial circles in a vertical axis.

[0016] In some example embodiments, the partial rectangle may have rounded corners. In some example embodiments, a length and a width of a complete rectangle corresponding to the partial rectangle may be the same or different.

[0017] In some example embodiments, a first radius of the first partial circle may be around 0.55 millimeters. In some example embodiments, a second radius of the second partial circle may be around 0.28 millimeters. In some example embodiments, a third radius of the third partial circle may be around 0.17 millimeters.

[0018] In some example embodiments, the first distance may be around 0.62 millimeters. In some example embodiments, the second distance may be around 0.34 millimeters. In some example embodiments, the third distance may be around 0.20 millimeters. In some example embodiments, the length of the complete rectangle may be around 1.15 millimeters. In some example embodiments, the width of the complete rectangle may be around 0.43 millimeters.

[0019] In some example embodiments, the polarization rotator may comprise a waveguide portion connecting the first portion and the second portion.

[0020] In some example embodiments, the first portion and the second portion may be of the first shape, and a thickness of the polarization rotator may be around 0.3 millimeters.

[0021] In some example embodiments, the first portion and the second portion may be of the second shape, and the thickness of the polarization rotator may be around 0.52 millimeters.

[0022] In some example embodiments, each of the first portion and the second portion may have a metal housing. In some example embodiments, an interior of the metal housing may be a vacuum or air.

[0023] In some example embodiments, the polarization rotator may be operated in a millimeter wave band.

[0024] In some example embodiments, an operational bandwidth of the polarization rotator may be from around 125 gigahertz (GHz) to around 180 GHz.

[0025] In some example embodiments, the polarization rotator may rotate a polarization angle of an electromagnetic wave by forty-five degrees at an output relative to an initial polarization angle at an input of the polarization rotator.

[0026] In some example embodiments, the polarization rotator is a one-piece machined part.

[0027] In a second aspect, there is provided a communication device. The communication device may comprise the polarization rotator.

[0028] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Some example embodiments will now be described with reference to the accompanying drawings, in which: FIGS. 1A-1B illustrate some example rotators related to some example embodiments of the present disclosure may be implemented; FIGS. 1C-1F illustrate some example use cases related to some example embodiments of the present disclosure may be implemented; FIGS. 2A-2B illustrate example polarization rotators in accordance with some example embodiments of the present disclosure; FIG. 3A-3B illustrate example spline curves in accordance with some example embodiments of the present disclosure; FIGS. 4A-4E illustrate example spline functions and rotator structures in accordance with some example embodiments of the present disclosure; FIGS. 5A-5B illustrate example inner and outer spline profiles in accordance with some example embodiments of the present disclosure; FIG. 6 illustrates example an electromagnetic propagation simulation including the spline shape rotator in accordance with some example embodiments of the present disclosure; FIGS. 7A-7E illustrate a spline curve shaped electric field electromagnetic simulation in accordance with some example embodiments of the present disclosure; FIGS. 8A-8B illustrate an electrical field (E-Field) simulation rotation at 180 GHz performed by the spline shape rotator in accordance with some example embodiments of the present disclosure; FIG. 9 illustrates a return loss |S1(1),1(1)| simulation in the D-Band in accordance with some example embodiments of the present disclosure; FIG. 10 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the D-Band in accordance with some example embodiments of the present disclosure; FIGS. 11A-11B illustrate the variation of the return loss with the rotator angular deviation in accordance with some example embodiments of the present disclosure; FIG. 12 illustrates a return loss simulation (co-polarization) in the E-Band in accordance with some example embodiments of the present disclosure; FIG. 13 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the E-Band in accordance with some example embodiments of the present disclosure; FIG. 14 illustrates a return loss simulation (co-polarization) in the 5.5 GHz - 8.5 GHz frequency band in accordance with some example embodiments of the present disclosure; FIG. 15 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in accordance with some example embodiments of the present disclosure; FIG. 16 illustrates a spline shape rotator machined part in accordance with some example embodiments of the present disclosure; FIGS. 17A-17B illustrate example multi-section rotator architectures in accordance with some example embodiments of the present disclosure; FIGS. 18A-18D illustrate example different views of the multi-section rotator in accordance with some example embodiments of the present disclosure; FIGS. 19A-19E illustrate a multi-section rotator E-Field simulation co-polarization mode in accordance with some example embodiments of the present disclosure; FIGS. 20A-20B illustrate a physical rotation of the vertical polarization in accordance with some example embodiments of the present disclosure; FIG. 21 illustrates a return loss simulation (co-polarization) in the D-Band in accordance with some example embodiments of the present disclosure; FIG. 22 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the D-Band in accordance with some example embodiments of the present disclosure; FIG. 23 illustrates a return loss simulation (co-polarization) in E-Band in accordance with some example embodiments of the present disclosure; FIG. 24 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in the E-Band in accordance with some example embodiments of the present disclosure; FIG. 25 illustrates a multi-section rotator return loss simulation (co-polarization) in accordance with some example embodiments of the present disclosure; FIG. 26 illustrates a multi-section rotator transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation in accordance with some example embodiments of the present disclosure; FIG. 27 illustrates a multi-section rotator machined part in accordance with some example embodiments of the present disclosure; and FIG. 28 illustrates an example communication device comprising the polarization rotator in accordance with some example embodiments of the present disclosure.

[0030] Throughout the drawings, the same or similar reference numerals represent the same or similar element.DETAILED DESCRIPTION

[0031] Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

[0032] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which the present disclosure belongs.

[0033] References in the present disclosure to "one embodiment," "an embodiment," "an example embodiment," and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0034] It may be understood that although the terms "first" and "second" etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "has", "having", "includes" and / or "including", when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. As used herein, "at least one of the following: " and "at least one of " and similar wording, where the list of two or more elements are joined by "and" or "or", mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0036] To obtain the requirements of ultra-high-speed communication, one promising approach is to exploit terahertz frequencies beyond 100 GHz. This allows for flexible RF transceivers or antenna arrays with multi-band and broad bandwidth capabilities. This is due to the substantially broader frequency spectrum that can be exploited in comparison to 5G. Additionally, compared with the microwave operating at traditional frequency bands, D-Band antenna beam widths are narrow, which minimizes RF interference between cells, and enables dense site deployment, and facilitates reuse of the frequency channels. One of the significant devices that will be required in 6G is a polarization rotator, as it is mandatory for many RF subsystems.

[0037] The electromagnetic (EM) waves are vector quantities characterized by both magnitude and phase. In wireless backhaul networks, these EM waves are typically linearly polarized, with polarization occurring in either the vertical or horizontal direction, or both at the same time. Thus, RF devices known as rotators are required to change the polarization angle of the wave and rotate it according to engineering requirements in the most efficient way as possible (impedance matching, transmission loss and cross polarization discrimination).

[0038] Future 6G backhaul wireless networks are expected to handle significantly larger amounts of data and provide higher data rates than the current 5G networks. One highly promising solution for operating 6G networks is the use of the D-Band, whose operational bandwidth is more than 40%, thereby enabling an increased capacity for the channel to carry data. From now on, the definition of operational bandwidth (%) is f H − f L f C × 100, where f L represents the start frequency of the operation frequency band, f H represents the end frequency and f C represents the center frequency.

[0039] Therefore, there is a need to propose a solution for the design of broadband RF rotators operating in extreme high frequencies, with a special focus on the D-Band to enable 6G networks. The embodiments of the present disclosure provide a more effective polarization rotator. For example, the polarization rotator can change the polarization angle of a linearly polarized electromagnetic wave by a device operating in high frequency band and broad band, focused on D-Band for future 6G applications, and thus can allow for better bandwidth control and significantly improved impedance matching.

[0040] For illustrative purposes, principles and example embodiments of the present disclosure of a polarization rotator will be described below with reference to FIG. 1A- FIG. 27. However, it is to be noted that these embodiments are given to enable the skilled in the art to understand inventive concepts of the present disclosure and implement the solution as proposed herein, and not intended to limit scope of the present application in any way.

[0041] Reference is made to FIGS. 1A-1B, which illustrate some example rotators related to some example embodiments of the present disclosure may be implemented. As illustrated in FIGS. 1A and 1B, the rotator 102 and the rotator 104 are broadband polarization rotators that operate in the millimeter wave band. The rotator 102 is symmetric, and the rotator 104 is symmetric, too. The rotator 102 and the rotator 104 are capable of rotating both vertical and horizontal polarized waves with the same performance, while maintaining a high level of cross polarization discrimination. This feature is significant for cross polarization interference cancellation (XPIC) in backhaul applications.

[0042] Reference is made to FIGS. 1C-1F, which illustrate some example use cases related to some example embodiments of the present disclosure may be implemented. It is to be understood that the following use cases will focus on the vertical polarization, however, the same level of performance when operating with horizontal polarization.

[0043] As shown in FIG. 1C, a use case 100C is a use case for a polarization rotator, and it arises when there is a need to rotate the polarization between one antenna and one outdoor unit (ODU). In the use case 100C, a vertically polarized wave is received by the antenna, and it may be transmitted to the ODU having a specific angle of polarization. Polarization rotation before entering the ODU may be required for various reasons, such as mechanical issues where the ODU is not installed symmetrically relative to the antenna, or when its input rectangular waveguide is not positioned linearly. Another reason for polarization rotation is to address clearance issues. Regardless of the technical reason for using a polarization rotator, it is crucial to maintain a low level of cross polarization (horizontal polarization) to enhance the cross polarization discrimination property.

[0044] In some cases, the ODU may need to be installed in a specific rotated orientation to avoid hitting the tower or causing issues with the RF cables connected to the ODU. In this case, a polarization rotator can be used to rotate the polarization before it enters the ODU, allowing for the ODU to be installed in the desired orientation while maintaining the correct polarization.

[0045] As shown in FIG. 1D, a use case 100D shows another application of a RF rotator. In the use case 100D, the RF rotator is integrated into flat or planar slot waveguide antennas. This type of antenna has raised significant interest in recent years due to its low profile, light weight, and high gain. However, slot array antennas often experience the problem of grating lobes. To address this issue, one solution is to rotate the polarization at a 45-degree angle. As this type of antenna is expected to be used in the D-Band for 6G, there will be a demand for high-performance and easily manufacturable polarization rotators.

[0046] An RF rotator is required in a large variety of radio frequency components. In a transmitter / receiver (transceiver module) widely used in ODUs, it may be necessary to rotate the wave polarization at the input and / or output of the power chain processing. As shown in FIG. 1E, a use case 100E shows that the vertical polarization has been rotated before coming into the ODU, and the transceiver must rearrange it again vertically before doing some RF processing. As shown in FIG. 1F, the use case 100F shows that an orthomode transducer (OMT) splits / combines two orthogonal polarizations into the same physical path, for instance a waveguide. In some cases, to optimize the OMT design is mandatory to rotate one of the polarizations. This may be justified by various factors such as the need for compactness, clearance, machining issues, RF performance, or cost reduction because the polarization rotation enables the transition from the wider waveguide section to the thinner one, and vice versa, providing more flexibility in the OMT design.

[0047] From the discussion with reference to FIGS. 1A-1F, it can be seen that the problems of the D-Band and broadband polarization rotator may be rotating the angle of polarization of one linear EM wave being symmetric in the operation mode (vertical and horizontal). Therefore, generally, the problem that the present disclosure solves may be changing the polarization angle of a linearly polarized electromagnetic wave by a device operating in high frequency band and broad band, focused on D-Band for future 6G applications. In some example embodiments, the RF device may have an original shape to integrate easy manufacturing processes with machining tolerances and should be a single part to avoid complicated assembly procedures, thus maintaining high compactness. In some example embodiments, the RF device may maintain excellent radio frequency properties such as return loss, transmission loss, and cross polarization discrimination.

[0048] Additionally, the solution of the present disclosure can achieve the best RF key performance figures such as return loss (RL), transmission loss, and cross polarization discrimination. Further, the solution of the present disclosure can be manufacturable as a single part with low thickness to avoid complicated assembly procedures and the generation of undesired resonant frequencies, which may cause RF transmission drops due to the assembly of multiple parts or excessively sharp shapes. This is because even a small deviation from the desired geometry during the manufacturing process can lead to a significant degradation in the RF performance of the rotator. Therefore, the present disclosure is carefully designed to minimize sensitivity to tolerance errors and ensure robust and reliable operation, especially in the D-Band where the wavelength is very small.

[0049] Reference is made to FIGS. 2A-2B, which illustrate example polarization rotators in accordance with some example embodiments of the present disclosure. As shown in FIG. 2A, the polarization rotator 200A comprises a portion 202 and a portion 204. The portion 202 is connected to the portion 204. In some example embodiments, the portion 202 and the portion 204 may be connected using a section 206. In some example embodiments, the section 206 may be a waveguide portion.

[0050] The portion 202 and the portion 206 are of a first shape with a contour of a spline curve. In some example embodiments, each of the portion 202 and the portion 204 may have a metal housing. The interior of the metal housing may be a vacuum or air.

[0051] In some example embodiments, the polarization rotator may be operated in a millimeter wave band. The operational bandwidth of the polarization rotator may be from around 125 GHz to around 180 GHz.

[0052] In some example embodiments, the contour (or the profile) of the spline curve may be modeled through interpolation of polynomial functions. The polynomial function may comprise coefficients and positive integer power variables. The combination of these polynomial functions may generate a wide range of possible coordinates, resulting in an extensive number of potential profiles. These profiles may be subsequently optimized using mathematical algorithms to ensure that each magnitude and phase component is best suited for impedance matching across the entire frequency band. Due to the large number of permutations available, the inherent property of the solution can allow for a balanced input / output impedance matching. The details of the spline curve and its modeling will be described with reference to FIGS. 3-16, and thus they will not be discussed herein.

[0053] As shown in FIG. 2B, the polarization rotator 200B comprises a portion 208 and a portion 210. The portion 208 is connected to the portion 210. In some example embodiments, the portion 208 and the portion 210 may be connected using a small and symmetric waveguide section 212.

[0054] The portion 208 and the portion 210 are of a second shape formed by combining a partial rectangle and a plurality of partial circles with different radii. In some example embodiments, the contour (profile) of the second shape is referred to as the multi-section.

[0055] The approach for determining the multi-section may involve generating multiple resonant frequencies, which when combined, may create a broad operational bandwidth similar to a multi carrier frequency spectrum. The selected shape may comprise several circles with different radii. With properly dimensioned, these circles resonate in parallel and are spaced in the frequency domain. The resulting effect is a broad operational bandwidth achieved with an extremely simple profile design. The details of the multi-section and its modeling will be described with reference to FIGS. 17-29, and thus they will not be discussed herein.

[0056] By implementing the embodiments of FIGS. 2A-2B, the polarization rotator is more effective, and thus it can allow for better bandwidth control and significantly improved impedance matching. In some example embodiments, the polarization rotator may be intended for use in the millimeter wave band, particularly in D-Band, which requires a broad frequency range, up to 45% of operational bandwidth. Additionally, the polarization rotator may be designed for ease of manufacturing by avoiding complex profiles and opting for single part designs.

[0057] It is to be understood that both spline shape and multi-section shape are simple and effective in solving the inherently complex manufacturing process required for RF devices operating at frequencies around 150 GHz and even higher frequencies. It may be indicated that the performance of the spline shape and multi-section rotators has been evaluated using RF simulations carried out with the time domain solver of CST microwave studio. This electromagnetic simulation software can provide highly accurate simulation results that validate the solutions of the presented disclosure.

[0058] Reference is made to FIGS. 3A-3B, which illustrate example spline curves in accordance with some example embodiments of the present disclosure. The spline curve may be a closed curve defined by a plurality of sub-functions, and a sub-function among the plurality of sub-functions defines a segment of the spline curve. In some example embodiments, the spline curve may be determined by interpolating a plurality of second-degree polynomial functions based on a plurality of points. In some example embodiments, a second-degree polynomial function among the plurality of second-degree polynomial functions may be defined by a plurality of coefficients and a plurality of positive integer power variables.

[0059] For example, as shown in FIG. 3A, points 302, 304 and 306 are three fixed points. The spline curve may be a function or curve that comprise multiple sub-functions where each sub-function applies to a different interval in the function domain. For example, the curves 308 and 310 may be determined by polynomials, such as two quadratic polynomials of the form y = a 2 x 2< + a 1 x + a 0 , where a 2 , a 1 and a 0 are constants. The spline curves can take on different forms, as shown in the curves 312 and 314. The interpolation with the quadratic polynomial may be done between the coordinates or knots. As shown in FIG. 3B, a cross 320 represents a knot. A quadratic polynomial 322 may be determined by these knots.

[0060] Depending on the values assigned to the coefficients (such as a 2 , a 1 and a 0 ), the spline curve can take too many different shapes. This may have significant implications as it provides a large degree of freedom in terms of design diversity.

[0061] Impedance matching in a broad frequency band can be a challenging task due to the need to handle to many multiple frequency components. Electromagnetic waves may react or are dependent obviously to the wavelength and on this, in the physical dimensions of the RF component. Even if a radio frequency device can be perfectly adapted to a particular frequency band, its RF performance will be degraded outside of the band due to their inappropriate dimensions.

[0062] The wide range of possible permutations of the control coefficients of the polynomial curves will try to fit at best with the proper impedance matching properties over the frequency domain. Therefore, the spline curve approach aims to utilize its inherent large degree of design freedom to solve the broadband impedance matching problem, seeking an extremely smooth variation over the entire targeted frequency band.

[0063] Reference is made to FIGS. 4A-4E, which illustrate example spline function and rotator structure in accordance with some example embodiments of the present disclosure. The spline curve may go through the plurality of points or is within a polygon determined based on the plurality of points. In some example embodiments, the number of the plurality of points for determining the spline curve may be comprised between fifteen and twenty-five. For example, as shown in FIG. 4A, an optimization algorithm may be used to establish the number of points (such as points 401, 402, 403 and 404 and so on) for the spline curve, which was determined to be 15-25 through an iterative process. It is to be understood that the numbers of points and the numbers of iterative process are only for illustrative purpose without any limitations.

[0064] The goal of the RF specification may be to optimize the return loss value, transmission loss and cross polarization discrimination over the broadest possible frequency band. In some example embodiments, the portion 202 and the portion 204 may be of the first shape and are rotationally symmetric around a vertical plane with each other. For example, once the spline curve is defined, the rotator architecture can be obtained by mirroring the shape about the vertical axis and then rotating the mirrored shape about the horizontal plane. For example, as shown in FIG. 4B, the portion 406 can be obtained by mirroring the portion 406 about the axis 408, and then rotating the mirrored portion 416 about the axis 410.

[0065] The main part of the spline shaped rotator may be defined by the former description of FIG. 3. However, to create an actual RF rotator, a non-discontinuous shape / profile should be obtained. Thus, the two symmetric spline shapes are connected using a small, symmetric waveguide section, as shown by part 412 in FIG. 4C. The part 412 is required to maintain an electrical continuity.

[0066] The resulting smoothed shape may be then used to fabricate the physical RF rotator (as shown in FIG. 4D and FIG. 4E) having lower thickness and an easier manufacturing than the traditional RF rotators. The continuous and original profile of the spline shape rotator may be an important feature that prevents the occurrence of undesired resonant frequencies due to the wrong combination of steps, section changes, or different parts inside a waveguide. One advantage is also its small thickness. For example, the thickness 414 in FIG. 4E may be only 0.3 millimeters after optimization in D-Band.

[0067] Reference is made to FIGS. 5A-5B, which illustrate example inner and outer spline profiles in accordance with some example embodiments of the present disclosure. FIG. 5 compares the inner and outer spline profiles. In the outer profile the spline smoothly goes through all points and touching them. In contrast, in the inner spline profile, the spline stays within the cage formed by the points. The advantage of the spline rotator is that the freedom degree goes further than the number of coefficients. The explanation is associated with the interpolation property of this type of curve. Once the coefficients are defined, the interpolation can be carried out in two different ways, following the inner profile, or choosing the outer profile. This means that a single spline shape design can be optimized for better RF performance or to avoid machining issues by following either profile.

[0068] As shown in FIG. 5A, a curve 502 shows an outer spline and a curve 504 shows an inner spline. The difference may not seem too significant but when the two profiles are directly overlapped (as shown in FIG. 5B), the design freedom becomes much clearer. By using the inner and outer spline profiles as a guide for the RF design, the actual machined profile can be expected to fall statistically within those limits. This may help to minimize the potential RF deterioration that may occur due to machining deviations during the manufacturing process. This can be an advantage in D-Band applications where the wavelength at 180 GHz is 1.67 millimeters and very sensitive to machining issues.

[0069] Reference is made to FIG. 6, which illustrates example electromagnetic propagation simulation including the spline shape rotator in accordance with some example embodiments of the present disclosure. The polarization rotator may rotate a polarization angle of an electromagnetic wave by forty-five degrees at an output relative to an initial polarization angle at an input of the polarization rotator. In some example embodiments, the polarization rotator may be a one-piece machined part.

[0070] For example, the spline shape rotator architecture has been defined in FIG. 5. The simulation may create two orthogonal and linear polarizations. That is, one vertically polarized wave is following the y-axis, represented by an arrow 602 coming into the circular waveguide. One horizontally polarized wave is following the x-axis and defined by an arrow 604. As the polarizations are orthogonal, they are out of phase 90 degrees. The study case is the rotation of the vertical polarization from 0 degree (y-axis) to 45 degrees towards the positive x-axis. The spline shape rotator is placed at 22.5 degrees as transition rotation angle.

[0071] As previously mentioned, one of the objectives of the present disclosure is to provide a technical solution that achieves high performance for future backhaul networks, focused on the D-Band. Consequently, the simulation of the E-field of the spline shaped rotator at 125 GHz (start frequency) and 180 GHz (end frequency) is shown in FIG. 7A-7E. The simulations operate in co-polarization mode and in cross polarization mode. All simulations exposed herein have been done with the time domain solver integrated by CST microwave studio.

[0072] Reference is made to FIGS. 7A-7E, which illustrate a spline curve shaped electric field electromagnetic simulation in accordance with some example embodiments of the present disclosure. For the D-Band (36%) simulation, in mono scale color ramp, the inner arrows (such as arrows 702 and 704) represent the simulated vertical direction of the electric field, which is defined by the larger arrow 706. This can ensure that the vectors are correctly oriented, and the energy transfer is proper. Additionally, the required broadband operation is clearly achieved as the simulation demonstrates uniform performance on the far spaced frequency samples (125 GHz and 180 GHz). More frequency samples can be shown but no undesired polarization rotation has been observed in any case.

[0073] Regarding the cross polarization mode in FIG. 7C, the inner arrows (such as arrows 708 and 710) are perfectly 180 degrees out of phase, as indicated by the two larger arrows (such as arrows 712 and 714), which will cancel the energy transmission providing high values of cross polarization discrimination.

[0074] As shown in FIG. 7E, the broadband performance in the D-Band can be also proven by the vector cancellation occurring over a broad range of frequency samples, similar to the co-polarization operation. Another proof of the present disclosure is the absence of energy across the center of the rotator which is consistent with the principle of operation. In FIG. 7E, the solid arrow (such as arrows 718 or 720) follows the angle of the energy null across the center which fits correctly with 22.5 degrees at 180 GHz (the scale was changed to improve the visual analysis).

[0075] Reference is made to FIGS. 8A-8B, which illustrate an E-Field simulation rotation at 180 GHz performed by the spline shape rotator. As shown in FIG. 8A, it provides a visual representation of the polarization rotation of a polarized wave at 180 GHz, assuming a rotation from 0 degree to 45 degrees in the vertical polarization. In FIG. 8A, it describes that a vertically polarized wave is introduced into the present disclosure through a rectangular waveguide. In FIG. 8B, the polarization is rotated by 45 degrees, with all the energy well oriented at the required angle. This is achieved once the rotator has completed the transition from 0 degrees to 22.5 degrees, before finishing at 45 degrees. S-parameter simulations are also conducted to evaluate the performance of the present disclosure in the D-Band, which is defined as ranging from 125 GHz to 180 GHz which corresponds to an operational bandwidth of 36%.

[0076] Reference is made to FIG. 9, which illustrates return loss |S1(1),1(1)| simulation 900 (co-polarization) in the D-Band in accordance with some example embodiments of the present disclosure. The return loss simulation (|S11|) is operating in co-polarization mode. That is, a vertical polarization relative to vertical polarization. The RL value of the spline shape rotator is better than 40 dB over the entire frequency band demonstrating outstanding performance for its use in applications where high precision machining is required. This is a first optimization of the present disclosure, it is believed that an improvement of around 10 GHz can be achieved, resulting in an operational bandwidth increase of up to 40%. This would meet the required specifications for 6G specifications.

[0077] Reference is made to FIG. 10, which illustrates transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 1000 where (1) indicates the vertical polarization or first mode and (2) indicates horizontal polarization or second mode in the D-Band in accordance with some example embodiments of the present disclosure. The simulated transmission loss, |S2(1),1(1)| parameter that defines the power ratio between output 2 and the input 1 of the same propagation mode (1) vertical, is almost 0 dB over the D-Band which proves again the correct RF operation of the spline shape rotator. With respect to cross-polarization, the value is extremely high, at around 100 dB, which will provide an exceptional level of isolation between polarizations. It is illustrated by the |S2(2),1(1)| parameter, the power ratio between the output 2 and the input 1 of the mode 2 (horizontal) over the mode 1 (vertical). To facilitate understanding, the mode 1 is referred to as the vertical polarization, and mode 2 is referred to as the horizontal polarization, as defined in FIG. 6.

[0078] It is to be understood that the spline shape rotator effectively prevents the wave for spinning out of control across the frequency band because no drop of energy (transmission loss) is predicted by the simulation. If there were any transmission loss at any frequency point, it would indicate that the angle of polarization of the output wave does not match the angular rotation that the rotator is designed to produce.

[0079] The following Table 1 provides the calculated values (in millimeters) of the spline curve coefficients and thickness T hs of the previous simulation results following the architecture of FIGS. 4A-4E. Table 1. Spline line coefficients of the rotator operating in D-Band.x 0 ,y 0 0.52,0.91x 1 ,y 1 0.37,0.89x 2 ,y 2 0.29,0.80x 3, y 3 0.24,0.69x 4 ,y 4 0.10,0.64x 5 ,y 5 0,0.53x 6 ,y 6 0.28,0.35x 7 ,y 7 0.33,0.16x 8 ,y 8 0.33, -0.17x 9 ,y 9 0.40, -0.34x 10 ,y 10 0.50, -0.39x 11 ,y 11 0.73, -0.42x 12 ,y 12 0.96, -0.32x 13 ,y 13 0.96,0x 14 ,y 14 0.86,0x 15 ,y 15 0.82,0.31x 16 ,y 16 0.69,0.50x 17 ,y 17 0.62,0.71x 18, y 18 0.63,0.83T hs 0.3 where point (x 0 ,y 0 ) may represent point 401 as an example, point (x 18 ,y 18 ) may represent point 404 as an example. T hs may represent the thickness 414 as an example.

[0080] Reduced thickness should be noted, 0.3 mm, resulting in only λ 8 at 125 GHz (bigger wavelength case). This thickness is lower compared with the traditional rotators and very attractive for extreme compactness requirements.

[0081] One of the objectives of the spline rotator is to achieve effective polarization rotation, and one of the frequent issues causing problems is the angular misalignment between the rotator and the input / output waveguides. This problem is particularly critical in millimeter wave applications, as a small deviation of the angular position becomes significantly large in relation to the operation wavelength.

[0082] Reference is made to FIGS. 11A-11B, which illustrate the variation of the return loss with rotator angular deviation in accordance with some example embodiments of the present disclosure. As shown in FIG. 11A, it shows the rotator angular deviation, and FIG. 11B shows the return loss and transmission loss parametric simulation of the angular sensitivity (in degrees). The RL (|S1(1),1(1)|) and transmission loss (|S2(1),1(1)|) show correct performance in the entire D-Band even when angular deviations up to 8 degrees from the nominal are applied.

[0083] Reference is made to FIG. 12, which illustrates a return loss simulation 1200 (co-polarization) in the E-Band in accordance with some example embodiments of the present disclosure. For the E-Band (25%) simulation, as shown in FIG. 12, the spline shape rotator has been also examined in the other millimeter wave band of interest, the E-Band (71 GHz - 86 GHz) with the aim of achieving an operational bandwidth of 25% (70 GHz - 90 GHz). The spline rotator as proposed can also operate correctly in this millimeter wave band, as the RL value is more than 35 dB.

[0084] Reference is made to FIG. 13, which illustrates transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 1300 in the E-Band in accordance with some example embodiments of the present disclosure. As shown in FIG. 13, the dashed line 1302 represents the transmission loss, and the dotted line 1304 represents the cross polarization. Similar to the D-Band, the successful operation of the present disclosure is demonstrated in the E-Band, with a transmission loss value near 0 dB and an isolation ratio between the two polarizations better than 90 dB across the entire frequency band.

[0085] Reference is made to FIG. 14, which illustrates return loss simulation 1400 (co-polarization) in the 5.5 GHz - 8.5 GHz frequency band in accordance with some example embodiments of the present disclosure. for the 5.5 GHz - 8.5 GHz (43%) simulation, to demonstrate the quality of the present disclosure, the present disclosure has pushed the limits of the spline shape rotator to achieve extremely high operational bandwidths. As such, RF simulations were carried out from 5.5 GHz up to 8.5 GHz, corresponding to an operational bandwidth of 43%. It is to be noted that this covers two distinct licensed backhaul frequency bands: 5.925 GHz - 7.125 GHz and 7.125 GHz - 8.5 GHz. FIG. 14 shows a RL value better than 40 dB on the entire frequency band.

[0086] Reference is made to FIG. 15, which illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 1500 in accordance with some example embodiments of the present disclosure. To confirm the proper operation of the spline shape rotator, both the transmission loss (dashed line 1502) and cross polarization discrimination (dotted line 1504) values were again analyzed. The results demonstrated excellent performance over nearly 45% of the operational bandwidth, which further validates the operating principle of the present disclosure. One point is that the intrinsic broadband performance of the present disclosure can enable adequate coverage of the unlicensed Backhaul band 5.725 GHz - 5.85 GHz, which further demonstrates the versatility of the present disclosure.

[0087] Reference is made to FIG. 16, which illustrates a spline shape rotator machined part in accordance with some example embodiments of the present disclosure. A view 1602 shows a front view. A view 1604 shows a side view. A view 1606 shows a perspective view. The spline shape rotator is illustrated in FIG. 16 as a machined part, and thus its simplicity is exceptional.

[0088] Reference is made to FIGS. 17A-17B, which illustrate example multi-section rotator architectures in accordance with some example embodiments of the present disclosure. The principle of the multi-section rotator is founded on the operation of multiple resonant frequencies working in parallel and spaced out in the frequency domain, creating a broad operational bandwidth. An approach to force several and spaced resonant frequency samples is to use a combination of various circles defined by distinct diameter, much like the design of circular waveguides used for different frequency bands.

[0089] In FIG. 17A, the architecture of the multi-section rotator is shown. The multi-section rotator may comprise a rectangular body 1740 and three circles 1734, 1736 and 1738 with progressively decreasing radii. The center of the leftmost edge of the rectangular body 1740 is center 1702. In some example embodiments, the length 1716 of the rectangular body 1710 may be around 1.15 millimeters, and the width 1742 of the rectangular body 1740 may be around 0.43 millimeters.

[0090] The center of first circle 1734 is center 1704. The radius of first circle 1734 is radius 1722. The center of second circle 1736 is center 1706. The radius of second circle 1736 is radius 1720. The center of third circle 1738 is center 1708. The radius of third circle 1738 is radius 1718. In some embodiments, the radius 1722 may be around 0.55 millimeters. The radius 1720 may be around 0.28 millimeters. The radius 1718 may be around 0.17 millimeters.

[0091] The radii 1718, 1720 and 1722 may not be identical. The first circle 1734, the second circle 1736 and the third circle 1738 may be moved further away from the center 1702. For example, Taking the centers 1704, 1706 and 1708 as references, the multi-section rotator may be also modeled by the horizontal displacement of the three circles 1734, 1736 and 1738 relative to the center 1702. For example, the first circle 1734 may be moved by a distance 1714 away from the center 1702. The second circle 1736 is moved by a distance 1712 away from the center 1704. The third circle 1738 may be moved by a distance 1710 away from the center 1706.

[0092] These distance parameters can be identical or distinct, and they play a significant role in determining the performance of the rotator. Regarding the vertical arrangement, the circles 1734, 1736 and 1738 are centered with respect to the rectangular body 1740. The rectangular body 1740 may be defined by the length 1716 and the width 1742. The length 1716 and the width 1742 may not have the same value.

[0093] As shown in FIG. 17B, the final outer profile of these four elements forms the half body 1732 of the multi-section rotator. Another half body is symmetric. The curve 1730 represents the outer profile of the third circle 1738. The curve 1728 represents the outer profile of the second circle 1736. The curve 1726 represents the outer profile of the first circle 1734. The curve 1724 represents the outer profile of the rectangular body 1740.

[0094] Reference is made to FIGS. 18A-18D, which illustrate example different view of the multi-section rotator in accordance with some example embodiments of the present disclosure. As shown in front view of FIG. 18A, the multi-section shape is vertically mirrored (such as half body 1802 and half body 1804) and then both half bodies 1802 and 1804 are connected by a rectangular section 1806. The rotated front view of FIG. 18B and a complete rotator perspective view of FIG. 18C are further shown in for better illustrative purpose.

[0095] Thus, the multi-section rotator is then obtained as a 3D model part (as shown in a perspective view of FIG. 18C) using the former defined profile. The thickness 1808 is shown in FIG. 18D), which is a side view of the multi-section rotator.

[0096] The multi-section rotator architecture has been defined in FIGS. 18A-18D, as in the same way that the spline curve rotator, the EM simulation of the present disclosure is carried out to evaluate its performance. The transition angle between the rotator and the input / output waveguides is again 22.5 degrees. Again, the main objective of the present disclosure is to offer a technical solution that can attain high performance for future backhaul networks, specially focused on the D-Band.

[0097] Reference is made to FIGS. 19A-19E, which illustrates a multi-section rotator E-Field simulation co-polarization mode in accordance with some example embodiments of the present disclosure. The EM simulation of the E-field of the multi-section rotator at 125 GHz and 180 GHz is depicted in FIGS. 19A-19E operating in co-polarization mode and cross polarization mode. For a D-Band (36%) simulation, the electric field in both frequency samples is properly transmitted and focused on the rotator center, following the inner arrows (such as arrows 1902 and 1904 in FIG. 19A), and directed vertically. Therefore, the multi-section architecture composed of three circles demonstrates correct RF operation.

[0098] Regarding the cross polarization mode, as shown in FIGS. 19C and 19D, the arrows cancels out against the output power because they are 180 degrees out of phase. To show more in detail this feature, in FIG. 19E, the solid arrow 1910 follows the angle of the energy null across the center which is properly 22.5 degrees at 180 GHz.

[0099] Reference is made to FIGS. 20A-20B, which illustrate the physical rotation of the vertical polarization in accordance with some example embodiments of the present disclosure. FIG. 20A shows a vertically polarized wave is introduced into the multi-section rotator through a rectangular waveguide. FIGS. 20B illustrates the output wave with the required change in its polarization angle 2002, demonstrating perfect transmission.

[0100] Reference is made to FIG. 21, which illustrates a return loss simulation 2100 (co-polarization) in the D-Band in accordance with some example embodiments of the present disclosure. FIG. 21 shows the return loss simulation in the D-Band defined from 125 GHz up to 180 GHz which corresponds to an operational bandwidth of 36%. The RL value is better than 35 dB in the entire required frequency band. With further optimization, the bandwidth could be increased approximately 10 GHz, resulting in a total operational bandwidth of 40%.

[0101] Reference is made to FIG. 22, which illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2),1(1)| simulation 2200 in the D-Band in accordance with some example embodiments of the present disclosure. As shown in FIG. 22, better energy transfer without power loss is demonstrated and extreme high value of polarization decoupling is observed, better than 100 dB.

[0102] The multi-section rotator has demonstrated excellent RF performance in terms of return loss, transmission loss, and cross-polarization decoupling, making it an ideal technical solution for D-Band applications. Furthermore, its exceptional margin of RF compliance and high operational bandwidth provide compensation for any machining deviation.

[0103] The following Table 2 shows the calculated dimensions (in millimeters) of the former D-Band multi-section rotator. Table 2 Dimensions of the broadband multi-section rotator in D-bandr 1,2,3 Value [mm]d 1,2,3 Value [mm]l 1,2 Value [mm]T hms r 1 0.55d 1 0.20l 1 0.430.52 mmr 2 0.28d 2 0.34l 2 1.15r 3 0.17d 3 0.62 where r1 represents radius 1718, r2 represents radius 1720, r3 represents radius 1722, d1 represents distance 1714, d2 represents distance 1712, d3 represents distance 1710, l1 represents width 1742, l2 represents length 1716, and T hms represents thickness 1808.

[0104] Even though the thickness is greater than that of the spline shape rotator, it still remains relatively small (0.22λ at 125 GHz, λ represents wave length), compared again with the traditional solutions. The simulated values are approximately consistent with resonant frequency multiples of λ / 2 directly decreasing with the increased frequency, with values of approximately λ / 4 at 125 GHz, λ / 6 at 155 GHz, and λ / 8 at 185 GHz. One explanation is that the former d 1 , d 2 and d 3 horizontal shifts must impact the exact resonant frequencies, and this may be considered during the design phase.

[0105] Reference is made to FIGS. 23 and 24. FIG. 23 illustrates a return loss simulation 2300 (co-polarization) in E-Band in accordance with some example embodiments of the present disclosure. FIG. 24 illustrates a transmission loss |S2(1),1(1)| and cross polarization |S2(2), 1(1)| simulation 2400 in the E-Band in accordance with some example embodiments of the present disclosure. Similar results in comparison with the spline shape rotator has been demonstrated, having RL better than 35 dB, cross polarization more than 100 dB and no transmission loss in 25% operational bandwidth. The multi-section rotator confirms its feasibility in the E-Band.

[0106] Reference is made to FIG. 25, which illustrates a multi-section rotator return loss simulation 2500 (co-polarization) in accordance with some example embodiments of the present disclosure. For a 5.5 GHz - 8.5 GHz (43%) simulation, the broadband multi-section rotator has proven excellent RF performances in the two most important millimeter wave bands. Additionally, it has also been tested for extreme high broadband operation, ranging from 5.5 GHz to 8.5 GHz, similar to the spline shaped rotator. The return loss simulation is shown in FIG. 25, and the RL level is better than 40 dB over 43% operational bandwidth.

[0107] Reference is made to FIG. 26, which illustrates a multi-section rotator transmission loss |S2(1), 1(1)| and cross polarization |S2(2),1(1)| simulation 2600 in accordance with some example embodiments of the present disclosure. As shown in FIG. 26, the transmission loss and cross polarization discrimination values of the multi-section rotator demonstrate the correct operation principle aimed by the present disclosure. The transmission loss, represented by the dashed line 2602, is minimal and the cross polarization discrimination, represented by the dotted line 2604, is high over nearly 45% of the operational bandwidth, indicating that there is no energy loss during polarization rotation and high cross polarization decoupling

[0108] Reference is made to FIG. 27, which illustrates multi-section rotator machined part in accordance with some example embodiments of the present disclosure. A view 2702 shows a front view. A view 2704 shows a side view. A view 2706 shows a perspective view. The spline shape rotator is illustrated in FIG. 27 as a machined part, and thus its simplicity is exceptional.

[0109] Reference is made to FIG. 28, which illustrates an example communication device 2800 comprising the polarization rotator in accordance with some example embodiments of the present disclosure. in some example embodiments, the communication device 2800 may be a transceiver. It is to be understood that this is only an example without any limitations.

[0110] The communication device 2800 may be any other devices such as a receiver or a transmitter and so on. The communication device 2800 may comprise the polarization rotator 2802 according to any embodiments discussed above. for example, the polarization rotator 2802 may be the polarization rotator 200A in FIG. 2A or the polarization rotator 200B in FIG. 2B. For brevity, the various embodiments of the polarization rotator will not be described again.

[0111] In general, the following advantages may be achieved by implementing the embodiments of the present disclosure. for example, high broadband feature (up to 45%) can be achieved. The rotator is better designed for D-Band, and it can avoid manufacturing deviations an is enhanced to prevent machining deviations due to the spline shape property. Reduced angular sensitivity can be achieved. There are no parts and / or machining intersections / sharp profiles on the exposed architectures, avoiding undesired resonant frequencies (transmission loss). The design requires only one piece to be machined, eliminating the need for assembly and simplifying the manufacturing process. Minimized thickness provides compactness solutions, especially for planar / flat antennas, OMTs and ODUs. The solution of the present disclosure to cover unlicensed backhaul frequency bands due to its broadband feature. No cross polarization issues were detected, improving the potential of dual polarization and XPIC backhaul networks. The spline curve and multi section rotators principle could be merged into one unique design to enhance even more the operational bandwidth and the RF properties.

[0112] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0113] Although the present disclosure has been described in languages specific to structural features and / or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Examples

Embodiment Construction

[0031]Principles of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. The disclosure described herein may be implemented in various manners other than the ones described below.

[0032]In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which the present disclosure belongs.

[0033]References in the present disclosure to "one embodiment," "an embodiment," "an example embodiment," and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particu...

Claims

1. A polarization rotator (200A, 200B) comprising: a first portion (202, 208); and a second portion (204, 210) connected to the first portion (202, 208), wherein the first portion and the second portion are of (i) a first shape (406) with a contour of a spline curve or (ii) a second shape (1732) formed by combining a partial rectangle (1740) and a plurality of partial circles (1734, 1736, 1738) with different radii.

2. The polarization rotator of claim 1, wherein the first portion (202) and the second portion (204) are of the first shape (406) and are rotationally symmetric around a vertical plane (408) with each other.

3. The polarization rotator of claim 1 or 2, wherein the spline curve is a closed curve defined by a plurality of sub-functions, and a sub-function among the plurality of sub-functions defines a segment of the spline curve.

4. The polarization rotator of any of claims 1-3, wherein: the spline curve is determined by interpolating a plurality of second-degree polynomial functions based on a plurality of points; and a second-degree polynomial function among the plurality of second-degree polynomial functions is defined by a plurality of coefficients and a plurality of positive integer power variables.

5. The polarization rotator of claim 1, wherein the first portion (208) and the second portion (210) have the second shape (1732) and are axially symmetric with each other.

6. The polarization rotator of claim 1 or 5, wherein the different radii progressively decrease in a direction away from the partial rectangle (1740).

7. The polarization rotator of any of claims 1, 5, and 6, wherein the number of the plurality of partial circles is three.

8. The polarization rotator of any of claims 1 and 5-7, wherein centers of the partial rectangle and the plurality of partial circles are aligned following a horizontal axis such that there is no displacement between the centers of the partial rectangle and the plurality of partial circles in a vertical axis.

9. The polarization rotator of any of claims 1 and 5-8, wherein: the partial rectangle has rounded corners; and a length (1716) and a width (1742) of a complete rectangle corresponding to the partial rectangle is the same or different.

10. The polarization rotator of any of claims 1-9, further comprising: a waveguide portion (412, 1806) connecting the first portion (202, 208) and the second portion (204, 210).

11. The polarization rotator of any of claims 1-10, wherein: the first portion (202) and the second portion (204) are of the first shape (406), and a thickness (414) of the polarization rotator (200A) is around 0.3 millimeters; or the first portion (208) and the second portion (210) are of the second shape (1732), and the thickness (1808) of the polarization rotator (200B) is around 0.52 millimeters.

12. The polarization rotator of any of claims 1-11, wherein: each of the first portion (202, 208) and the second portion (204, 210) has a metal housing; and an interior of the metal housing is a vacuum or air.

13. The polarization rotator of any of claims 1-12, wherein the polarization rotator is operated in a millimeter wave band.

14. The polarization rotator of any of claims 1-13, wherein the polarization rotator (200A, 200B) rotates a polarization angle of an electromagnetic wave by forty-five degrees at an output relative to an initial polarization angle at an input of the polarization rotator.

15. A communication device (2800) comprising: the polarization rotator (2802) of any of claims 1-14.

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