1-bit ultra-wideband reflective array unit with angle stability characteristic

Abstract

The invention discloses a 1-bit ultra-wideband reflective array unit with an angle stability characteristic. The 1-bit ultra-wideband reflective array unit comprises a first metal layer, a first F4B layer, a metal ground layer, an FR4 layer, a second F4B layer and a bias layer, wherein the first metal layer, the first F4B layer, the metal ground layer, the FR4 layer, the second F4B layer and the bias layer are sequentially distributed from top to bottom, the first metal layer comprises a first metal patch, a second metal patch and a third metal patch, the second metal patch is located between the first metal patch and the third metal patch, and the second metal patch is located between the first metal patch and the third metal patch. The first metal patch is connected with the second metal patch through a first pin diode, the second metal patch is connected with the third metal patch through a second pin diode, and the second metal patch is connected with the bias layer and the metal ground layer. The device has the characteristics of simple structure, easiness in processing, low cost and excellent performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communications and relates to a 1-bit ultra-wideband reflective array unit with angle stability characteristics. Background Art

[0002] With the iterative advancement of wireless communication technology and the widespread application of radar detection technology, higher performance requirements are placed on antennas used to transmit and receive electromagnetic waves, such as adjustable beams, broadband, and high gain.

[0003] In recent years, reflectarray antennas have attracted widespread attention due to their small size, light weight, low profile, low cost, and ease of manufacturing. Traditional reflectarray antennas are usually composed of a series of reflective units, which can generally provide a continuous reflection phase. The most significant difference between a reconfigurable reflectarray antenna (RRA) and a traditional reflectarray antenna lies in the introduction of digitalized units. For example, a 1-bit antenna corresponds to only two unit types: "0" and "1," while a 2-bit antenna corresponds to four types: 00, "01," "10," and "11." Generally speaking, the greater the number of bits, the more accurate the reflection phase on the reflector, and the closer the antenna's actual performance matches the calculated value. By orderly arranging these reflective units on the reflector, different functional reflection beam characteristics can be obtained, significantly reducing design difficulty and complexity. While increasing the number of bits results in more precise quantization of the reflection phase on the reflector, it also significantly increases the complexity of antenna unit design and the difficulty of reflectarray antenna fabrication. The design of a 1-bit reflectarray antenna can significantly reduce the overall system design complexity and fabrication cost, and therefore has broad application prospects in future practical communications engineering applications.

[0004] 5G communications represent a promising future technology that promises to meet high data rate targets. Gbps-level peak data rates will require fast switching mechanisms. Transmission in the millimeter-wave (4.8 GHz to 4.9 GHz) and even higher short-wavelength frequency bands requires increasing the bandwidth and efficiency of antenna systems to meet these data rate requirements. However, millimeter-wave frequencies exhibit significant path loss and short communication distances. To implement 5G communications at these higher frequencies, significant improvements to the architecture of current communications systems are urgently needed. Increasing the bandwidth of antenna systems is one of the most effective and direct approaches.

[0005] 1-bit reconfigurable reflectarray antennas have simple design and cost-effectiveness, and have obvious advantages in beamforming flexibility, indicating their potential for widespread application in communication engineering. Broadband technology is an important development direction in the field of wireless communications. Broadband antennas can operate efficiently in a wide frequency range, provide the advantage of multi-band coverage, and improve the overall performance and efficiency of communication systems. Therefore, how to design broadband antennas has become a hot topic and research direction in the domestic and international communications community in recent years. However, although many reconfigurable smart surface units have been designed, these units generally have the problem of narrow operating bandwidth due to the combination of RRA microstrip elements and lumped elements. In existing RRA unit designs, the operating bandwidth of most 1-bit RRA units is still less than 20%.

[0006] In recent studies, researchers have focused on designing broadband 1-bit RRA units. In the paper [Han J, Li L, Liu G, et al. A wideband 1-bit 12×12 reconfigurable beam-scanning reflectarray: Design, fabrication, and measurement [J]. IEEE Antennas and Wireless Propagation Letters, 2019, 18(6): 1268-1272.], a 1-bit broadband reconfigurable reflectarray was designed. The unit has a simple structure and uses only one pin diode to implement a 1-bit broadband RRA unit. However, the results show that the relative bandwidth (180°±20°) of the RRA unit only reaches 12% (4.7-5.3 GHz), which is insufficient to meet the needs of future wireless communication technologies. The literature [Zhou SG, Zhao G, Xu H, et al. A wideband 1-bit reconfigurable reflectarray antenna at Ku-band [J]. IEEE Antennas and Wireless Propagation Letters, 2021, 21 (3): 566-570.] designed a 1-bit broadband reconfigurable reflectarray antenna at Ku-band. The design is based on a multi-layer stacking structure to expand the operating bandwidth. Although this form can effectively expand the operating bandwidth by 23.8% (12.9-16.5 GHz), the multi-layer stacking structure will increase the volume of the array unit and increase the cost of the antenna design. The literature [Xiang BJ, Dai X, Luk K MA wideband low-cost reconfigurable reflectarrayantenna with 1-bit resolution[J]. IEEE Transactions on Antennas and Propagation, 2022, 70(9): 7439-7447.] designed a low-cost broadband reconfigurable reflectarray antenna. This unit design is based on the magnetoelectric dipole form and has a wide operating bandwidth of 40% (10-15GHz). However, the unit structure is still relatively complex. Each unit uses four metal patches and thirteen metal through-holes, which increases the difficulty of processing.

[0007] 1-bit reconfigurable reflectarrays have been widely studied due to their simple structure, ease of control, and low cost, and have great application prospects. However, as mentioned above, their operating bandwidth is still relatively narrow.

[0008] Although many broadband antenna elements have been designed, they still have some problems. Therefore, this paper designs an ultra-wideband 1-bit reconfigurable reflectarray element with angle stability. This element has a simple structure, is easy to process, is low-cost, and has excellent performance. It has a very broad application scenario in the future communication field. Summary of the Invention

[0009] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a 1-bit ultra-wideband reflective array unit with angle stability characteristics. The unit has a wide operating bandwidth, a simple structure, easy processing, low cost and excellent performance.

[0010] To achieve the above objectives, the present invention discloses a 1-bit ultra-wideband reflective array unit with angle-stable characteristics, comprising a first metal layer, a first F4B layer, a metal ground layer, an FR4 layer, a second F4B layer, and a bias layer; wherein the first metal layer, the first F4B layer, the metal ground layer, the FR4 layer, the second F4B layer, and the bias layer are distributed in sequence from top to bottom, the first metal layer comprises a first metal patch, a second metal patch, and a third metal patch, wherein the second metal patch is located between the first metal patch and the third metal patch, the first metal patch and the second metal patch are connected via a first PIN diode, the second metal patch and the third metal patch are connected via a second PIN diode, and the second metal patch is connected to the bias layer and the metal ground layer, respectively.

[0011] The further improvement of the 1-bit ultra-wideband reflective array unit with angle stability characteristics of the present invention is:

[0012] Furthermore, the second metal patch is connected to the bias layer through a first metal through-hole.

[0013] Furthermore, one end of the first metal through hole is connected to the second metal patch, and the other end of the second metal through hole passes through the first F4B layer, the metal ground layer, the FR4 layer and the second F4B layer and is connected to the bias layer.

[0014] Furthermore, the second metal patch is connected to the metal layer through a plurality of second metal through holes.

[0015] Furthermore, one end of each second metal through-hole is connected to the second metal patch, and the other end of each second metal through-hole passes through the first F4B layer and is connected to the metal ground layer.

[0016] Furthermore, the number of the second metal through holes is six.

[0017] Furthermore, it includes a plurality of third metal through holes, all of which are divided into two rows, wherein the first metal layer, the first F4B layer, the metal ground layer, the FR4 layer, the second F4B layer and the bias layer are all located between the two rows of third metal through holes.

[0018] Furthermore, the number of third metal through-holes in each row of third metal through-holes is seven.

[0019] Furthermore, the first pin diode and the second pin diode are both MACOM MA4AGFCP910 pin diodes.

[0020] Furthermore, the first metal patch and the third metal patch act as electric dipoles for receiving and radiating electromagnetic waves. By applying a bias voltage on the bias layer, the on-off states of the first PIN diode and the second PIN diode are simultaneously changed. A ring structure is formed through the second metal through-hole and the metal ground layer and is equivalent to a magnetic dipole, causing secondary resonance of the RRA unit.

[0021] The present invention has the following beneficial effects:

[0022] The angularly stable 1-bit ultra-wideband reflectarray unit described in this invention utilizes a magnetoelectric dipole structure, leveraging the complementary properties of electric and magnetic dipoles to achieve an ultra-wide operating bandwidth exceeding 50%. This design offers the widest operating bandwidth in the Ku-band. This design incorporates angular stability into the design of the ultra-wideband 1-bit reconfigurable reflectarray unit, incorporating two rows of third metal vias on either side of the unit. This ensures virtually unchanged bandwidth at low oblique angles of incidence and remains greater than 30% at higher oblique angles, surpassing the bandwidth of most 1-bit RRA units. Furthermore, this design boasts a simple structure, low cost, and ease of fabrication, along with the widest bandwidth in the Ku-band, promising broad applications in future communications and the field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0024] Figure 1a It is a structural diagram of the present invention;

[0025] Figure 1b A top view of the present invention;

[0026] Figure 1c is a side view of the present invention;

[0027] Figure 2a is the equivalent circuit diagram of the pin diode;

[0028] Figure 2b Schematic diagram of the parameters of the PIN diode;

[0029] Figure 3 for Figure 3 Schematic diagram of the reflection phase and phase difference in two states of the RRA unit;

[0030] Figure 4 Schematic diagram of the amplitude of the two states of the RRA unit;

[0031] Figure 5 Schematic diagram of unit reflection phase and phase difference at an incident angle of 0°;

[0032] Figure 6 Schematic diagram of unit reflection phase and phase difference at an incident angle of 10°;

[0033] Figure 7 Schematic diagram of unit reflection phase and phase difference at an incident angle of 20°;

[0034] Figure 8 Schematic diagram of unit reflection phase and phase difference at an incident angle of 30°;

[0035] Figure 9 Schematic diagram of unit reflection phase and phase difference at an incident angle of 40°;

[0036] Figure 10 Schematic diagram of unit reflection phase and phase difference at an incident angle of 50°.

[0037] Among them, 11 is the first metal patch, 12 is the second metal patch, 13 is the third metal patch, 14 is the first pin diode, 15 is the second pin diode, 2 is the first F4B layer, 3 is the metal ground layer, 4 is the FR4 layer, 5 is the second F4B layer, 6 is the bias layer, 71 is the first metal through hole, 72 is the second metal through hole, and 73 is the third metal through hole. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0040] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0042] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0043] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0046] refer to Figure 1a 、 Figure 1b and Figure 1c The 1-bit ultra-wideband reflective array unit with angle stability described in the present invention includes a first metal layer, a first F4B layer 2, a metal ground layer 3, an FR4 layer 4, a second F4B layer 5, and a bias layer 6. The first metal layer, the first F4B layer 2, the metal ground layer 3, the FR4 layer 4, the second F4B layer 5, and the bias layer 6 are arranged in order from top to bottom. The first metal layer includes a first metal patch 11, a second metal patch 12, and a third metal patch 13. The second metal patch 12 is located between the first metal patch 11 and the third metal patch 13. The first metal patch 11 and the second metal patch 12 are connected via a first pin diode 14, and the second metal patch 12 and the third metal patch 13 are connected via a second pin diode 15.

[0047] One end of the first metal via 71 is connected to the second metal patch 12 , and the other end of the second metal via 72 passes through the first F4B layer 2 , the metal ground layer 3 , the FR4 layer 4 and the second F4B layer 5 and is connected to the bias layer 6 .

[0048] One end of each second metal through-hole 72 is connected to the second metal patch 12 , and the other end of each second metal through-hole 72 passes through the first F4B layer 2 and is connected to the metal ground layer 3 .

[0049] In this embodiment, a plurality of third metal vias 73 are further included. All third metal vias 73 are divided into two rows, wherein the first metal layer, the first F4B layer 2, the metal ground layer 3, the FR4 layer 4, the second F4B layer 5 and the bias layer 6 are all located between the two rows of third metal vias 73.

[0050] In this embodiment, the number of the second metal through holes 72 is six.

[0051] In this embodiment, the number of the third metal through-holes 73 in each row of the third metal through-holes 73 is seven.

[0052] It should be noted that the first and third metal patches 11 and 13 act as electric dipoles, receiving and radiating electromagnetic waves. By applying a bias voltage to the bias layer 6, the on / off states of the first and second PIN diodes 14 and 15 are simultaneously altered. The second metal via 72 and the metal ground layer 3 form a ring structure that functions as a magnetic dipole, causing secondary resonance in the RRA unit. The electric and magnetic dipoles work together to achieve the ultra-wideband characteristics of the RRA unit. Finally, two rows of third metal vias 73 are introduced around the RRA unit to provide angular stability. To ensure optimal performance, the antenna was optimized using HFSS.

[0053] It should be noted that the reference Figure 2a and Figure 2b PIN diodes have a fast response speed and are usually integrated into RRA units to achieve reconfiguration. The present invention selects MACOM MA4AGFCP910 PIN diodes as lumped elements in ultra-wideband RRA units. The equivalent circuit and detailed parameters of the PIN diodes can be found in the product manual on the official website, as shown in the figure. Figure 2a and Figure 2b As shown, the on and off states of the pin diode can be modeled in the simulation software as a series connection of a 7.8Ω resistor R and a 30pH inductor L or a series connection of a 25fF capacitor C and a 30pH inductor L. The pin diode has low insertion loss and extremely fast response speed. In both states, the RRA unit can achieve a wide operating bandwidth.

[0054] When the DC bias point at the bottom is applied with different voltage states, the first and second PIN diodes 14 and 15 at the top will simultaneously turn on and off depending on the positive and negative bias voltages. Compared to the off state, the on state connects the disconnected portion of the magnetoelectric dipole. The first and second PIN diodes 14 and 15 and the second metal patch 12 not only connect the first and second metal patches 11 and 12, which function as electric dipoles, but also connect the second metal via 72 and the metal ground layer 3, which function as magnetic dipoles. This introduces perturbations when the magnetoelectric dipole functions as a reflection unit, resulting in two different reflection phase responses.

[0055] The proposed RRA unit model is simulated under periodic boundary conditions using ANSYS HFSS software, and the unit model is optimized. In the case of vertical incident waves, the phase and amplitude of the reflected wave are as follows: Figure 3 and Figure 4 As shown, the phase difference between the two states of the RRA unit meets 180°±20° in the 9.2-16.3 GHz frequency band, and the relative bandwidth exceeds 50%.

[0056] Figure 4 The amplitude curves for the RRA unit in its two states clearly show that in the off state, the unit has two resonances, consistent with the magnetoelectric dipole radiation mechanism, corresponding to the magnetic dipole and the electric dipole, respectively. In the on state, a perturbation introduced in the center of the unit shifts the two resonances to the right. It is these different resonances in the two states that cause the phase difference. The deeper resonance in the on state results in greater unit loss, primarily due to the heat generated by the current flowing through the resistor in the unit when the PIN diode is on, which inevitably results in energy loss.

[0057] When an RRA is operating, oblique incident electromagnetic waves are unavoidable. Compared to normal incidence, the RRA's performance deteriorates. This degradation can often be explained by the theory of reflection interference models of multi-layer units and the interaction of multiple reflections between adjacent RRA units. Since this unit model uses only two dielectric layers separated by a metal layer 4, only the interaction between adjacent units is considered. Two rows of third metal vias 73 are introduced on either side of the unit to serve as electromagnetic barriers. The distance between the third metal vias 73 is much smaller than the operating wavelength. These electromagnetic barriers isolate multiple reflections of electromagnetic waves between adjacent atoms, thereby minimizing the impact of oblique incident electromagnetic waves on unit performance.

[0058] like Figure 5-Figure 9 As shown in the figure, the reflection phase and phase difference between the unit with and without metal through-holes when the electromagnetic wave is incident at different angles. As can be seen from the figure, under oblique incidence, due to the influence between the units, the phase and phase difference of the model without metal through-holes have undergone significant changes within the working bandwidth when the incident angle is 10°, which will greatly affect the performance of the RRA unit. Figure 9 As shown in the figure, after the introduction of metal vias, when the incident angle is 50°, the relative operating bandwidth of the unit can still exceed 30%. This shows that the introduction of metal vias can greatly improve the performance of the RRA unit when working at oblique incidence. Although the performance of the unit is slightly reduced, the unit model still has a relatively wide operating bandwidth.

[0059] Those skilled in the art will readily identify other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0060] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A 1-bit ultra-wideband reflectarray unit with angular stability, characterized in that: The invention comprises a first metal layer, a first F4B layer (2), a metal ground layer (3), an FR4 layer (4), a second F4B layer (5) and a bias layer (6); wherein the first metal layer, the first F4B layer (2), the metal ground layer (3), the FR4 layer (4), the second F4B layer (5) and the bias layer (6) are sequentially distributed from top to bottom; the first metal layer comprises a first metal patch (11), a second metal patch (12) and a third metal patch (13); wherein the second metal patch (12) is located between the first metal patch (11) and the third metal patch (13); the first metal patch (11) and the second metal patch (12) are connected via a first pin diode (14); the second metal patch (12) and the third metal patch (13) are connected via a second pin diode (15); and the second metal patch (12) is respectively connected to the bias layer (6) and the metal ground layer (3).

2. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 1, characterized in that: The second metal patch (12) is connected to the bias layer (6) through a first metal through hole (71).

3. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 2, characterized in that: One end of the first metal through hole (71) is connected to the second metal patch (12), and the other end of the second metal through hole (72) passes through the first F4B layer (2), the metal ground layer (3), the FR4 layer (4) and the second F4B layer (5) and is connected to the bias layer (6).

4. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 1, wherein: The second metal patch (12) is connected to the metal layer (3) via a plurality of second metal through holes (72).

5. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 4, characterized in that: One end of each second metal through hole (72) is connected to the second metal patch (12), and the other end of each second metal through hole (72) passes through the first F4B layer (2) and is connected to the metal ground layer (3).

6. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 4, characterized in that: The number of the second metal through holes (72) is six.

7. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 1, characterized in that: The invention also includes a plurality of third metal through holes (73), wherein all the third metal through holes (73) are divided into two rows, wherein the first metal layer, the first F4B layer (2), the metal ground layer (3), the FR4 layer (4), the second F4B layer (5) and the bias layer (6) are all located between the two rows of third metal through holes (73).

8. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 1, wherein: The number of third metal through holes (73) in each row of third metal through holes (73) is seven.

9. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 1, characterized in that: The first pin diode (14) and the second pin diode (15) are both MACOM MA4AGFCP910 pin diodes.

10. The 1-bit ultra-wideband reflectarray unit with angle stability according to claim 4, characterized in that: The first metal patch (11) and the third metal patch (13) act as electric dipoles for receiving and radiating electromagnetic waves. By applying a bias voltage on the bias layer (6), the on-off states of the first PIN diode (14) and the second PIN diode (15) are changed simultaneously. A ring structure is formed through the second metal through hole (72) and the metal ground layer (3) and is equivalent to a magnetic dipole, thereby causing secondary resonance of the RRA unit.

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