Ka-band wideband high-power grid type circular polarizer and design and manufacturing method thereof

Abstract

The application belongs to the technical field of millimeter wave antennas, and specifically discloses a Ka-band wide-band high-power grid-type circular polarizer and a design and manufacturing method thereof. The circular polarizer comprises a frame, a plurality of parallel and spaced polarizing sheets arranged in the frame, a phase-adjusting boss integrally formed on each polarizing sheet, a polarizing sheet positioning block fixedly arranged on the frame, a locking piece arranged at one end of the frame, and an elastic tensioning mechanism arranged at the other end of the frame. One end of the polarizing sheet is a fixed end, and the other end is a free end. The locking piece limits and fixes the fixed end of each polarizing sheet on the frame. The elastic tensioning mechanism continuously applies tension to the free end of each polarizing sheet to keep each polarizing sheet in a straight state. The application compensates for inductive phase shift dispersion by integrally forming the phase-adjusting boss on the polarizing sheet to expand the working bandwidth, and guarantees the flatness of the grid and the environmental adaptability through the elastic tensioning mechanism, and has the advantages of wide-band, high-power capacity, stable structure, and simple assembly.

Description

Technical Field

[0001] This invention belongs to the field of millimeter-wave antenna technology, specifically relating to a Ka-band wideband high-power grid-strip circular polarizer and its design and manufacturing method. Background Technology

[0002] Circularly polarized waves have significant applications in communication, navigation, and remote sensing. Compared to linearly polarized waves, circularly polarized waves offer significant advantages in resisting rain and fog attenuation, suppressing multipath effects, eliminating polarization distortion, and improving communication quality. High-power microwave sources are mostly linearly polarized; to obtain circularly polarized radiation, a circular polarizer is needed to convert linearly polarized waves into circularly polarized waves. A circularly polarized wave can be decomposed into two spatially and temporally orthogonal, equal-amplitude linearly polarized waves. Therefore, the basic principle of realizing a circularly polarized antenna lies in generating two spatially orthogonal linearly polarized electric field components with equal amplitudes and a 90° phase difference.

[0003] Based on the above principles, those skilled in the art have developed various types of circular polarizers. In the millimeter-wave band, circular polarizers are mainly divided into two categories: waveguide circular polarizers and grating (strip) type circular polarizers. Among them, waveguide circular polarizers are difficult to achieve high-power transmission in the millimeter-wave band due to size limitations; while grating circular polarizers composed of rectangular metal strips have outstanding advantages such as simple structure, easy fabrication, and easy expansion to high-frequency and high-power applications, thus becoming an important technical direction for high-power circular polarizers in the millimeter-wave band.

[0004] Among numerous millimeter-wave frequency bands, the Ka-band, due to its abundant spectral resources and excellent propagation characteristics, has broad application prospects in broadband communication and high-resolution detection systems. This also places higher demands on the performance of circular polarizers. Specifically, the working principle of a grating-type circular polarizer is as follows: the polarization direction of the incoming wave forms a 45° angle with the grating, and the electric field is decomposed into two orthogonal components with equal amplitude and initial phase. The polarization component perpendicular to the grating remains unaffected, while the polarization component parallel to the grating becomes a waveguide mode, with a longer wavelength and slower propagation speed. Therefore, by appropriately selecting the geometry of the grating, the phase difference between the two orthogonal components can reach 90°, thus achieving the conversion from linear polarization to circular polarization.

[0005] However, when applying the aforementioned grating-type circular polarizer to the Ka band, its inherent physical characteristics present a series of pressing technical challenges. Firstly, the shorter wavelength of the Ka band (approximately 7.5mm to 11.3mm) necessitates a corresponding reduction in the structural size of the circular polarizer, while simultaneously imposing extremely stringent requirements on the machining and assembly precision of components—micrometer-level dimensional deviations can lead to significant degradation in polarization conversion performance. Secondly, the increasingly congested frequency resources within this band place higher demands on the operating bandwidth of the circular polarizer. Furthermore, high-power transmission systems require the circular polarizer to withstand higher microwave power, which places greater demands on the selection of materials and the structural strength of the device.

[0006] Meanwhile, existing bar-type circular polarizers have the following shortcomings in meeting the above requirements: First, in terms of bandwidth, the phase shift of bar-type polarizers mainly relies on inductive phase shift, which is highly sensitive to frequency, making it difficult for the polarizer's operating frequency band to cover the growing wideband application requirements of the Ka band; second, in terms of accuracy, the metal bars in bar-type circular polarizers are thin and long strip structures, which are prone to bending and deformation due to their own gravity after processing, while the Ka band has extremely stringent requirements for bar straightness and assembly accuracy, further exacerbating the risk of performance degradation; third, in terms of environmental adaptability, under conditions such as temperature changes and stress deformation, the relative positional accuracy between the bars in existing bar-type circular polarizers is difficult to maintain, causing the electrical performance to deteriorate with changes in environmental conditions, making it difficult to meet the high reliability requirements of Ka band applications.

[0007] Based on the above analysis, it is clear that how to realize a grid-type circular polarizer with wide bandwidth, high power capacity, and high precision in the Ka band, while simultaneously solving the problems of deformation control and environmental adaptability during grid assembly, has become a pressing technical challenge in this field.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a Ka-band wideband high-power grating-bar circular polarizer and its design and manufacturing method, so as to solve the technical problems of limited bandwidth, difficulty in controlling grating deformation, and insufficient environmental adaptability of existing grating-bar circular polarizers in Ka-band applications.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] On one hand, the present invention provides a Ka-band broadband high-power grid-strip circular polarizer, comprising:

[0012] The frame, which is made of rigid materials, forms the load-bearing frame of the circular polarizer;

[0013] Multiple polarization plates, each of which is a long strip of conductive metal sheet, are arranged in parallel and spaced apart within the frame, with one end of each polarization plate being a fixed end and the other end being a free end;

[0014] Phase-tuning protrusions: Multiple phase-tuning protrusions are integrally formed on the body of each polarization sheet. The phase-tuning protrusions are used to provide capacitive phase shift to compensate for the inductive phase shift frequency dispersion of the polarization sheet.

[0015] A polarization plate positioning block is fixedly disposed on the frame, and each polarization plate passes through the polarization plate positioning block. The polarization plate positioning block is used to constrain the position of each polarization plate in the width direction and the thickness direction, and to maintain the degree of freedom in the length direction of each polarization plate.

[0016] A locking element is disposed on the frame and connected to the fixed end of each polarization sheet, for limiting and fixing the fixed end of each polarization sheet to the frame;

[0017] An elastic tensioning mechanism is disposed on the frame and connected to the free end of each of the polarization plates, for applying a continuous tension to each of the polarization plates to keep each of the polarization plates in a straight state.

[0018] Furthermore, the enclosure is formed by fastening channel steel and diagonal braces together with screws.

[0019] Furthermore, the polarizer is made of brass.

[0020] Furthermore, the polarization plate has a double-layer grid structure.

[0021] Furthermore, the phase-adjusting boss is a cylindrical boss, and each of the phase-adjusting bosses is arranged in an array along the length direction on the polarization plate.

[0022] Furthermore, each of the polarization plates is symmetrically provided with the phase-adjusting protrusions on both its front and back sides.

[0023] Furthermore, the locking element is a locking post, the surface of which is provided with an annular groove, and the fixed end of each polarization sheet is provided with a locking hole. The locking post passes through each of the locking holes, and the edge of each of the locking holes is embedded in the annular groove. The two ends of the locking post are limited to the frame.

[0024] Furthermore, the elastic tensioning mechanism includes a spring steel wire, a T-shaped steel block, and a fixed steel column. The spring steel wire is bent and threaded through the frame. The T-shaped steel block is connected to the spring steel wire. The fixed steel column is disposed on the T-shaped steel block. The free ends of each polarization plate are sleeved on the fixed steel column. The elastic restoring force of the spring steel wire is transmitted to each polarization plate through the T-shaped steel block and the fixed steel column, forming the continuous tension.

[0025] Furthermore, the fixed steel column is provided with an annular groove, and the free end of each polarization plate is provided with a through hole. The through hole is sleeved on the fixed steel column, and the edge of the through hole is embedded in the annular groove.

[0026] On the other hand, the present invention also provides a design and manufacturing method for a Ka-band broadband high-power grid-strip circular polarizer, comprising the following steps:

[0027] Step 1: Based on the electrical performance requirements of the target operating frequency band, determine the thickness of each polarizer through simulation optimization. The spacing between adjacent polarization plates and the longitudinal distance between two adjacent polarization plates , so that the determined thickness ,spacing and longitudinal distance The electrical performance requirements of the target operating frequency band must be met.

[0028] Step 2: Provide a frame by connecting rigid materials into a square frame structure, which serves as the load-bearing frame for the circular polarizer;

[0029] Step 3: Provide multiple polarization plates, each of which is a long strip of conductive metal sheet, and integrally form multiple phase-adjusting protrusions on the sheet of each polarization plate;

[0030] Step 4: Fix the polarization sheet positioning block on the frame, and pass each polarization sheet parallel and spaced through the polarization sheet positioning block so that the polarization sheet positioning block constrains the position of each polarization sheet in the width and thickness directions, and maintains the degree of freedom in the length direction of each polarization sheet.

[0031] Step 5: Define one end of each polarized sheet as a fixed end and the other end as a free end. Set a locking member on the frame and connect it to the fixed end of each polarized sheet. Use the locking member to limit and fix the fixed end of each polarized sheet to the frame.

[0032] Step 6: Install the elastic tensioning mechanism on the frame and connect it to the free ends of each polarized sheet. The elastic tensioning mechanism includes a spring steel wire, a T-shaped steel block, and a fixed steel column. The spring steel wire is bent and threaded through the frame. The T-shaped steel block is connected to the spring steel wire. The fixed steel column is installed on the T-shaped steel block. The free ends of each polarized sheet are sleeved on the fixed steel column. The spring steel wire generates an elastic restoring force, which is transmitted to each polarized sheet through the T-shaped steel block and the fixed steel column, applying a continuous tension along the length of each polarized sheet to keep each polarized sheet in a straight state.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The Ka-band wideband high-power grid-strip circular polarizer provided by this invention uses a phase-shifting protrusion integrally formed on the polarizer to compensate for the frequency dispersion of the inductive phase shift of the polarizer itself by capacitive phase shift, effectively reducing the difference in phase shift at the high and low frequency ends. This significantly improves the axial ratio performance of the circular polarizer in the Ka-band, with a relative bandwidth of ≥16%, and solves the problem of limited bandwidth caused by the frequency sensitivity of inductive phase shift in existing grid-strip polarizers.

[0035] 2. This invention, by setting up an elastic tensioning mechanism, uses the continuous tension of the spring steel wire to keep the thin and narrow polarization plates in a straight state, effectively avoiding phase errors caused by the bending deformation of the grid bars due to their own gravity; at the same time, the elastic deformation of the spring steel wire can adaptively compensate for thermal expansion and contraction caused by temperature changes and deformation caused by the force on the frame, ensuring that the relative position accuracy between each polarization plate remains stable during operation, significantly improving the environmental adaptability of the circular polarizer.

[0036] 3. This invention uses an integrated processing technology to directly process the polarization plate with phase adjustment boss from the same metal sheet, ensuring the dimensional accuracy and consistency of the polarization plate and phase adjustment boss, and avoiding the cumulative error caused by separate assembly; combined with the all-metal structure design, the circular polarizer can withstand an average power of 20kW and a peak power of 200kW, meeting the high power capacity requirements of millimeter-wave high-power transmission systems. Attached Figure Description

[0037] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the polarization plate structure used in this invention;

[0040] Figure 2 This is a schematic diagram showing the dimensional parameters of the grid-type circular polarizer of the present invention;

[0041] Figure 3 This is a schematic diagram of the overall structure of the grid-type circular polarizer of the present invention;

[0042] Figure 4 This is a reference schematic diagram of the overall three-dimensional structure of the grid-type circular polarizer of the present invention;

[0043] Figure 5 These are schematic diagrams of the side structures of the grid-type circular polarizer of the present invention; where (a) is a bottom view; (b) is a front view; and (c) is a top view.

[0044] Figure 6 This is a partial reference diagram of the top of the three-dimensional model of the grid-type circular polarizer of the present invention;

[0045] Figure 7 This is a partial reference diagram of the bottom of the three-dimensional model of the grid-type circular polarizer of the present invention;

[0046] Figure 8 This is a schematic diagram of the grid-type circular polarizer frame structure of the present invention;

[0047] Figure 9 This is a schematic diagram illustrating the tensioning principle of the spring steel wire in this invention;

[0048] Figure 10 The simulation diagram shows the voltage standing wave ratio (VSWR) of a grid-type circular polarizer without phase adjustment bosses.

[0049] Figure 11 This is a simulation diagram of the phase difference between the two orthogonal polarization components in a comparative grid-type circular polarizer without phase adjustment bosses.

[0050] Figure 12 The simulation diagram shows the voltage standing wave ratio (VSWR) of the grid-type circular polarizer with phase adjustment bosses in this invention.

[0051] Figure 13 This is a simulation diagram of the phase difference between the two orthogonal polarization components in the state of the grid-type circular polarizer with phase adjustment bosses of the present invention.

[0052] in:

[0053] 1 is the frame; 2 is the polarization plate; 3 is the phase adjustment boss; 4 is the polarization plate positioning block; 5 is the locking component; 6 is the elastic tensioning mechanism; 61 is the spring steel wire; 62 is the T-shaped steel block; 63 is the fixed steel column. Detailed Implementation

[0054] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0055] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0056] Example 1

[0057] Please see Figures 1 to 9 This embodiment provides a Ka-band broadband high-power grid-type circular polarizer, which is mainly composed of a frame 1, multiple polarizing plates 2, phase-adjusting bosses 3, polarizing plate positioning blocks 4, locking components 5, and an elastic tensioning mechanism 6. The circular polarizer adopts a louver-like grid-type structure, with multiple elongated polarizing plates 2 arranged in parallel and spaced intervals inside the frame 1 to form a periodic metal grid array. In this design, one end of each polarizer 2 is fixed to the frame 1 by a locking member 5, and the other end is continuously pulled by an elastic tensioning mechanism 6, so that all polarizers 2 remain straight in the working state. Multiple phase-adjusting protrusions 3 are integrally formed on the body of each polarizer 2 to compensate for the frequency dispersion of the inductive phase shift of the polarizer 2 itself, thereby expanding the working bandwidth of the circular polarizer. The polarizer positioning block 4 is set on the frame 1 to constrain the position of each polarizer 2 in the width and thickness directions, ensuring the consistency of the spacing between adjacent polarizers 2 and the parallelism between each polarizer 2.

[0058] Specifically, such as Figures 3 to 5 and Figure 8As shown, the frame 1 is constructed from rigid materials, including but not limited to metals, engineering plastics, carbon fiber composites, and other structural materials with sufficient bending strength and rigidity. The rigidity of the frame 1 should ensure that, under the continuous tension of the elastic tensioning mechanism 6, the deformation of the frame 1 does not affect the relative positional accuracy between the polarizers 2. From an electrical perspective, the frame 1 only serves a mechanical load-bearing function and does not directly participate in the interaction between the electromagnetic waves and the polarizers 2. Therefore, the shape of the frame 1 is not limited by electrical performance; square, rectangular, circular, and polygonal shapes are all acceptable, as long as the effective area of ​​the polarizers 2 within the frame 1 can cover the beam illumination range. In this embodiment, the frame 1 adopts a square frame structure formed by fastening channel steel and diagonal braces with screws. This is because the square frame has the following advantages: 1) The projection of the antenna radiation beam on the plane of the frame is approximately circular, and the square is the smallest circumscribed rectangle of this circle, which saves the most material compared to a rectangle; 2) All polarization plates 2 within the square have uniform lengths, eliminating the need for multiple specifications, and making design, processing, and assembly the simplest; 3) The square structure has good symmetry, the polarization plates 2 have good stress consistency, and the elastic tensioning mechanism 6 is arranged neatly; 4) The processing of the square channel steel frame is much simpler than that of a circular or irregularly shaped frame, resulting in the lowest processing cost. Among them, the channel steel is selected from metal profiles with good bending strength, and its length, width, and height are determined according to the installation space and opening size requirements of the actual application scenario; the diagonal braces are set at the four corners of the frame 1 to enhance the structural rigidity and torsional resistance of the frame 1, ensuring that the frame 1 does not deform significantly when the elastic tensioning mechanism 6 applies continuous tension.

[0059] like Figure 1 and Figure 4 As shown, the polarizing sheet 2 is a long, strip-shaped conductive metal sheet, integrally formed from a brass plate. The polarizing sheets 2 are arranged parallel and spaced apart within the frame 1, with the spacing between adjacent polarizing sheets 2... And the thickness of polarizer 2 The operating frequency band of the circular polarizer was determined through simulation optimization. One end of each polarizer 2 is a fixed end, and the other end is a free end. The polarizer 2 has a double-layer grid structure, meaning two layers of polarizer 2 are spaced apart in the electromagnetic wave propagation direction, with a longitudinal distance between the two layers... Determined through simulation optimization.

[0060] It should be noted that in this embodiment, multiple phase-modulation protrusions 3 are integrally formed on the body of each polarization sheet 2. The phase-modulation protrusions 3 are cylindrical protrusions, and the phase-modulation protrusions 3 are arranged in an array along the length direction on the body of the polarization sheet 2. Each polarizer 2 has symmetrically arranged phase-tuning bosses 3 on both its front and back sides. The reason for adopting a symmetrical arrangement on both sides is as follows: First, the field distribution of the polarization components parallel to the grid bars on both sides of the polarizer is symmetrical about the central plane of the plate. The symmetrical arrangement on both sides ensures the consistency of the electromagnetic boundary conditions on both sides, avoiding the asymmetry introduced by a single-sided boss that leads to additional reflections and higher-order modes, thereby deteriorating the standing wave ratio and axial ratio. Second, the capacitive phase shift of the phase-tuning boss is equivalent to a parallel capacitor. The loading of a single-sided boss is only half that of a double-sided boss. The dispersion compensation required in the Ka band is large, and a single-sided boss cannot provide enough capacitive phase shift to offset the frequency slope of the inductive phase shift. In addition, the symmetrical arrangement on both sides makes the input impedance on both sides of the polarizer symmetrical, ensuring that the reflection coefficients of the two orthogonal components are consistent and the amplitude balance is not disrupted. At the same time, single-sided milling of brass sheet will cause warping deformation due to uneven material removal. The symmetrical processing on both sides helps to keep the plate flat. The phase-tuning bosses 3 and the polarizer 2 are integrally formed from the same metal sheet. During processing, an array of phase-adjusting bosses 3 are milled on one side of the brass plate using a CNC machining center. Then, the phase-adjusting bosses 3 on the back are machined using the reverse side. Finally, a wire EDM machine is used to cut the entire polarizer 2 out of the brass plate as a whole, achieving precision machining of the polarizer 2 structure. The integrally machined polarizer 2 has a unified reference and dimensional positioning tolerances, which is conducive to achieving high-precision assembly.

[0061] like Figure 5 and Figure 8 As shown, the polarization plate positioning block 4 is fixedly mounted on the opposite two channel steels of the frame 1, specifically within pre-machined grooves on the channel steel, and secured with screws. Each polarization plate 2 passes through the polarization plate positioning block 4. The polarization plate positioning block 4 has positioning holes that fit with the polarization plates 2 with clearance, used to constrain the position of each polarization plate 2 in the width and thickness directions, while maintaining freedom of movement in the length direction. In other words, the polarization plate positioning block 4 restricts the displacement of the polarization plates 2 in the width and thickness directions, ensuring that each polarization plate 2 is parallel to each other and has a consistent spacing, while allowing the polarization plates 2 to slide freely in the length direction, providing freedom of movement for the tensioning action of the elastic tensioning mechanism 6.

[0062] like Figure 5 and Figure 7As shown, the locking element 5 is disposed on the frame 1 and connected to the fixed end (i.e., the bottom end of the frame) of each polarization plate 2, and is used to limit and fix the fixed end of each polarization plate 2 to the frame 1. The locking element 5 is a locking post, and the surface of the locking post has an annular groove. The fixed end of each polarization plate 2 has a locking hole, and the locking post passes through each locking hole, with the edge of each locking hole embedded in the annular groove. The two ends of the locking post are limited to the frame 1. After the locking post passes through the locking hole of the fixed end of each polarization plate 2, the edge of the locking hole is engaged in the annular groove of the locking post, preventing the polarization plate 2 from slipping off along the axial direction of the locking post; the two ends of the locking post are limited by the side wall of the frame 1, providing a reaction force fulcrum for the tension of the elastic tensioning mechanism 6.

[0063] like Figure 5 , Figure 6 and Figure 9 As shown, the elastic tensioning mechanism 6 is mounted on the frame 1 and connected to the free ends (i.e., the top of the frame) of each polarization plate 2, and is used to apply a continuous tension to each polarization plate 2 to keep each polarization plate 2 in a straight state. The elastic tensioning mechanism 6 includes a spring steel wire 61, a T-shaped steel block 62, and a fixed steel column 63. The spring steel wire 61 is bent and passes through the frame 1, with both ends of the spring steel wire 61 supported in circular holes in the side wall of the frame 1, and the middle part is bent. The T-shaped steel block 62 is connected to the spring steel wire 61, and after the spring steel wire 61 passes through the hole in the T-shaped steel block 62, the T-shaped steel block 62 is located in the middle of the spring steel wire 61. The fixed steel column 63 is mounted on the T-shaped steel block 62 and has an annular groove. Each polarization plate 2 has a through hole at its free end, which is fitted onto the fixed steel column 63, and the edge of the through hole is embedded in the annular groove.

[0064] In this embodiment, the elastic tensioning mechanism 6 tensions four polarized plates 2 as a group. Each T-shaped steel block 62 is provided with two fixed steel columns 63, and four polarized plates 2 are hung on one T-shaped steel block 62, that is, two polarized plates 2 are sleeved on each fixed steel column 63. They are simultaneously tensioned by the same elastic tensioning mechanism 6. Figure 6As shown, the spring steel wire 61 undergoes bending elastic deformation when it is bent and threaded onto the frame 1, generating an elastic restoring force. This elastic restoring force is transmitted to each polarization plate 2 through the T-shaped steel block 62 and the fixed steel column 63, applying a continuous tensile force along the length of each polarization plate 2. Under the action of this continuous tensile force, each polarization plate 2 is straightened and remains in a straight state. The reaction fulcrum provided by the locking member 5 at the fixed end and the continuous tensile force applied by the elastic tensioning mechanism 6 at the free end form a complete force system. The locking member 5 limits and fixes the fixed end of the polarization plate 2 to the frame 1, and the elastic tensioning mechanism 6 continuously pulls the free end of the polarization plate 2. The two work together to keep the polarization plate 2 taut along its entire length. The continuous tension of the elastic tensioning mechanism 6 also has an adaptive compensation function: when changes in ambient temperature cause thermal expansion and contraction of the frame 1, the elastic deformation of the spring steel wire 61 is automatically adjusted accordingly. When the frame 1 expands, the spring steel wire 61 is further stretched and the elastic force increases; when the frame 1 contracts, the spring steel wire 61 retracts and the elastic force decreases, thus maintaining a continuous tension on the polarization plate 2. Similarly, when the frame 1 is subjected to force and undergoes slight deformation, the spring steel wire 61 can also adaptively compensate to ensure that the relative positional accuracy between the polarization plates 2 remains stable during operation.

[0065] The assembly relationship of the above components is as follows: the frame 1 serves as the basic load-bearing frame; the polarization plate positioning block 4 is fixed at both ends of the frame 1 to constrain the width and thickness of each polarization plate 2 inserted therein; the locking member 5 limits and fixes the fixed ends of each polarization plate 2 at the fixed end of the frame 1; the elastic tensioning mechanism 6 continuously pulls the free ends of each polarization plate 2 at the free end of the frame 1 through the elastic restoring force of the spring steel wire 61, and each set of elastic tensioning mechanism 6 corresponds to tightening four polarization plates 2; each polarization plate 2 remains straight under the combined action of the locking member 5 and the elastic tensioning mechanism 6, and remains parallel to each other and with consistent spacing under the constraint of the polarization plate positioning block 4.

[0066] In this embodiment, the circular polarizer operates such that a linearly polarized wave is incident at a 45° angle onto the grid-type polarizer array. The electric field is decomposed into two orthogonal components: one perpendicular to the grid and the other parallel to the grid. The polarization component perpendicular to the grid is unaffected, while the polarization component parallel to the grid experiences a phase delay due to the inductive effect of the grid. This phase delay can be mitigated by appropriately selecting the geometry (thickness) of the polarizer 2. ,spacing Interlayer longitudinal distance This allows the phase difference between two orthogonal components to reach 90°, thereby enabling the conversion from linearly polarized waves to circularly polarized waves.

[0067] However, the performance of traditional grid-strip circular polarizers degrades significantly when the frequency deviates from the center frequency. The fundamental reason for this is the frequency dispersion effect of the inductive phase shift. Specifically, the polarization component parallel to the grid strips drives electrons to oscillate along the length of the grid strips, forming an induced current and generating an induced magnetic field. This effect can be equivalent to having an inductor in series in the transmission path, with an inductive reactance X... L =ωL=2πfL increases with increasing frequency, therefore the phase lag φ of this polarization component L(f) It increases with increasing frequency (φ) L ∝f). For circular polarization conversion, the phase difference between the two orthogonal components is required to be constant at 90° across the entire frequency band. However, in the case where only inductive phase shift exists, due to φ L(f) The slope of the phase shift with frequency is greater than the constant value corresponding to the ideal 90° phase difference, resulting in excessive phase shift at the high-frequency end and insufficient phase shift at the low-frequency end when deviating from the center frequency. This leads to a large difference in phase shift between the high and low frequencies, thus causing frequency dispersion. This application addresses this by introducing the phase-adjusting boss 3, which is equivalent to applying a capacitive load to the grid bar, with a capacitive susceptance B... C =ωC= 2πfC increases with increasing frequency, and the resulting capacitive phase shift is opposite in direction to the inductive phase shift (capacitors provide a leading phase shift, and inductors provide a lagging phase shift). By rationally designing the size, number, and distribution of the phase-shifting bosses 3, the capacitive and inductive phase shifts are superimposed within the operating frequency band, φ L(f) The increasing frequency trend is compensated by the capacitive phase shift, which flattens the frequency slope of the total phase shift, reduces the difference in phase shift between high and low frequencies, and keeps the phase difference close to 90° over a wider frequency range, thus effectively widening the operating bandwidth of the circular polarizer. At the same time, capacitive loading also helps to improve the input impedance matching of the grid bars, keeping the voltage standing wave ratio (VSWR) at a low level over a wide frequency range.

[0068] In addition, the elastic tensioning mechanism 6 ensures the flatness of the polarizer 2 along its entire length, and ensures that the relative positional accuracy between each polarizer 2 is stable and reliable, thereby meeting the stringent requirements of Ka-band for assembly accuracy.

[0069] Example 2

[0070] This embodiment provides a design and manufacturing method for a Ka-band broadband high-power grid-strip circular polarizer, which can be used to manufacture the circular polarizer described in Embodiment 1. The method includes the following steps.

[0071] Step 1: Design parameter simulation optimization

[0072] Based on the electrical performance requirements of the target operating frequency band, the thickness of each polarizer 2 was determined through simulation optimization. Spacing between adjacent polarization plates 2 and the longitudinal distance between two adjacent polarization plates , so that the determined thickness ,spacing and longitudinal distance It meets the electrical performance requirements of the target operating frequency band.

[0073] In this embodiment, the target operating frequency band is the Ka band, and its electrical performance requirements are shown in Table 1:

[0074] Table 1 Electrical Performance Requirements for Ka-band Circular Polarizers

[0075]

[0076] The aforementioned dimensional parameters were determined through the following simulation optimization process: A three-dimensional model of the double-layer grating array was established in the HFSS full-wave simulation software, using periodic boundary conditions and Floquet port excitation, with the incident wave polarization direction forming a 45° angle with the grating length direction. The polarization plate thickness was used as the basis for the optimization. ,spacing Longitudinal distance between two layers Diameter of the phase-shifting boss The spacing p1 along the length of the polarizer and p2 along the width of the bosses are used as design variables. The optimization objectives are to minimize the axial ratio, voltage standing wave ratio (VSWR), and phase difference and 90° deviation between the two orthogonal components within the operating frequency band. Constraints include an axial ratio ≤ 3dB, VSWR ≤ 1.5, insertion loss ≤ 0.5dB, and polarization isolation ≥ 20dB across the entire frequency band. First, the sensitivity and reasonable value range of each variable are determined through single-variable parameter scanning. Then, a genetic algorithm is used for multi-objective optimization iteration. The parameter combination with the best overall performance is selected from the Pareto optimal solution set. The optimal parameters are then verified through full-band simulation and critical dimensional tolerance analysis. During tolerance analysis, the polarizer thickness is used as the basis for the calculation. ,spacing Longitudinal distance Boss diameter and height The analysis condition was to use fluctuations within a tolerance range of ±0.03mm to evaluate the sensitivity of each dimensional deviation to electrical performance and confirm that the electrical performance still meets the requirements under the worst tolerance combination.

[0077] In this embodiment, simulation optimization determined the following dimensions: the thickness w of polarizer 2 is 0.58 mm, the spacing ds between adjacent polarizers 2 is 1.8 mm, and the longitudinal distance L between two adjacent polarizer layers is 1 mm. The specific dimensional parameters of the phase-adjusting boss 3 are: boss diameter d is 0.8 mm, boss height h is 0.81 mm (excluding polarizer thickness), the spacing p1 of the bosses along the length direction of the polarizer is 4.2 mm, and the spacing p2 of the bosses along the width direction of the polarizer is 1.7 mm (symmetrically distributed about the centerline in the width direction). The above combination of dimensional parameters meets the electrical performance requirements listed in Table 1.

[0078] Step 2, Frame Processing

[0079] A frame 1 is provided, which connects rigid materials into a square frame structure to serve as the load-bearing frame for the circular polarizer. Specifically, channel steel and diagonal braces are fastened together with screws to form a sturdy square frame structure. The length and width of the frame 1 are determined according to the installation space and opening size requirements of the actual application scenario, and the height of the frame 1 is determined according to the longitudinal distance and assembly space required for the double-layer grid structure. In this embodiment, the length (length1) of the frame 1 is 590mm, the width (width1) is 590mm, and the height (height1) is 48mm.

[0080] Step 3: Polarization sheet processing

[0081] Multiple polarizer plates 2 are provided, each being a long, strip-shaped conductive metal sheet. Multiple phase-adjusting bosses 3 are integrally formed on the sheet of each polarizer plate 2. Specifically, an array of phase-adjusting bosses 3 is milled from one side of a brass plate using a CNC machining center, and then the phase-adjusting bosses 3 on the reverse side are machined. Finally, a wire EDM machine is used to cut the entire polarizer plate 2 from the brass plate. The phase-adjusting bosses 3 are cylindrical bosses, and they are arranged in an array along the length of the polarizer plate 2, with symmetrical phase-adjusting bosses 3 on both the front and back sides of each polarizer plate 2. The integrally machined polarizer plate 2 has a uniform reference and dimensional positioning tolerances. In this embodiment, the polarizer 2 is processed according to the size parameters determined by simulation optimization in step 1: the thickness w is 0.58mm, the spacing ds between adjacent polarizers 2 is 1.8mm, and the longitudinal distance L between the two layers of the double-layer grid structure is 1mm; the diameter d of the phase-adjusting boss 3 is 0.8mm, the height h is 0.81mm (excluding the polarizer thickness), the spacing p1 along the length direction of the polarizer is 4.2mm, and the spacing p2 along the width direction is 1.7mm (symmetrically distributed about the center line of the width direction).

[0082] Step 4: Install the positioning block

[0083] The polarization plate positioning block 4 is fixedly mounted on the frame 1. Specifically, the polarization plate positioning block 4 is fixed in the pre-machined grooves on the opposite side channel steel and tightened with screws. Each polarization plate 2 is inserted parallel and spaced apart through the polarization plate positioning block 4, so that the polarization plate positioning block 4 constrains the position of each polarization plate 2 in the width and thickness directions, while maintaining freedom in the length direction of each polarization plate 2. The polarization plate positioning block 4 has positioning holes that fit with the polarization plates 2 with clearance, ensuring that each polarization plate 2 is parallel to each other and has a consistent spacing, while allowing the polarization plates 2 to slide freely in the length direction.

[0084] Step 5: Lock the fixed end

[0085] One end of each polarization plate 2 is defined as the fixed end, and the other end as the free end. A locking member 5 is mounted on the frame 1 and connected to the fixed end of each polarization plate 2. The locking member 5 limits and fixes the fixed end of each polarization plate 2 to the frame 1. Specifically, the locking member 5 is a locking post with an annular groove on its surface. Each polarization plate 2 has a locking hole at its fixed end. The locking post is inserted into each locking hole, so that the edge of each locking hole is embedded in the annular groove, and both ends of the locking post are limited to the frame 1.

[0086] Step 6: Elastic tension at the free end

[0087] An elastic tensioning mechanism 6 is mounted on the frame 1 and connected to the free ends of each polarization plate 2. The elastic tensioning mechanism 6 includes a spring steel wire 61, a T-shaped steel block 62, and fixed steel columns 63. Specifically, two fixed steel columns 63 are first inserted into the T-shaped steel blocks 62, and then the through holes at the free ends of each polarization plate 2 are fitted onto the fixed steel columns 63. The annular grooves on the fixed steel columns 63 prevent the polarization plates 2 from slipping off. Then, the T-shaped steel block 62 is placed in the groove of the channel steel 10, and the spring steel wire 61 is inserted into the round hole on the side wall of the channel steel at the corresponding position, passing through the hole on the T-shaped steel block 62 and then into the round hole on the other side wall of the channel steel 10. At this time, the T-shaped steel block 62 is located in the middle of the spring steel wire 61, and the two ends of the spring steel wire 61 are supported in the round holes on the two side walls of the channel steel 10.

[0088] By pinching each polarization plate 2 and pulling it down through the polarization plate positioning block 4 fixed on the channel steel 6, the spring steel wire 61 bends and deforms, generating tension. After the fixed end of each polarization plate 2 is limited and fixed to the frame 1 by the locking member 5, the hand is released. Each polarization plate 2 contracts due to the rebound force of the spring steel wire 61, and the locking member 5 locks the polarization plate 2, generating a shear force to prevent the spring steel wire 61 from contracting. At this time, the elastic restoring force of the spring steel wire 61 is transmitted to each polarization plate 2 through the T-shaped steel block 62 and the fixed steel column 63, applying a continuous tension along the length of each polarization plate 2, keeping each polarization plate 2 in a straight state. In this embodiment, each T-shaped steel block 62 is provided with two fixed steel columns 63, and four polarization plates 2 are hung on one T-shaped steel block 62, that is, two polarization plates 2 are sleeved on each fixed steel column 63. They are simultaneously tightened by the same elastic tensioning mechanism 6, which has high group tightening assembly efficiency and uniform force on each polarization plate 2. Following the above method, all polarizers 2 are tightened and fixed one group at a time until all polarizers 2 are installed in place, thus obtaining the Ka-band broadband high-power grid bar circular polarizer of this embodiment.

[0089] Experimental verification

[0090] To verify the technical effect of the present invention, this embodiment uses the above-described design and manufacturing method to prepare two sets of circular polarizer samples: one with a phase-adjusting boss (the present invention) and the other without a phase-adjusting boss (comparative example). The polarizer dimensions (thickness) of the two sets of samples are as follows. =0.58mm, spacing =1.8mm, longitudinal distance =1mm), material (brass), number of layers (double layer) and other structural parameters are kept the same, the only difference being the presence or absence of the phase adjustment boss 3. The only difference between the comparative example and the sample of the present invention is that the polarization sheet of the comparative example does not have the phase adjustment boss 3, and the rest of the structure (frame 1, polarization sheet 2, polarization sheet positioning block 4, locking element 5, elastic tensioning mechanism 6) is the same as the sample of the present invention.

[0091] 1. Voltage Standing Wave Ratio Comparison Test

[0092] from Figure 10 The test results show that the return loss of the two orthogonal polarization ports of the comparative model (without phase modulation protrusions) is better than -22dB across the entire frequency band from 32GHz to 38GHz. Based on the conversion relationship between return loss and voltage standing wave ratio (VSWR), the corresponding VSWR is ≤1.17; from... Figure 12 According to the test results, the present invention (with phase modulation protrusion) has a return loss of better than -20dB in the entire frequency band from 32.26GHz to 37.92GHz, and the corresponding voltage standing wave ratio (VSWR) is ≤1.22.

[0093] contrast Figure 10 and Figure 12 As can be seen, the voltage standing wave ratios (VSWR) of both devices are far superior to the design specification of 1.5 throughout the entire operating frequency band, indicating good port matching performance. Although the introduction of the phase-modulation boss slightly increases the VSWR at the high-frequency end (port 2) (from 1.08 to 1.22) due to structural discontinuities, it remains at an excellent level and does not affect the normal operation of the device. The above results show that the introduction of the phase-modulation boss 3 does not significantly degrade the impedance matching characteristics. This invention maintains good port matching performance while widening the operating bandwidth. In summary, the core function of the phase-modulation boss lies in compensating for phase dispersion, as detailed in the following phase difference comparison test.

[0094] 2. Phase difference comparison test of two orthogonal components

[0095] from Figure 11 The test results show that the phase difference between the two orthogonal components in the comparative model (without phase-tuning protrusions) has a large slope as the frequency changes, exhibiting a monotonically decreasing trend, only approaching 90° at the low-frequency end, while the phase difference rapidly deviates from 90° at the high-frequency end (only about 69° at 38GHz), satisfying a relative bandwidth of approximately 7.2% with |Δφ-90°|≤±10°. Figure 13Based on the test results, after capacitive phase shift compensation by the phase shifting boss, the phase difference-frequency curve of the present invention (with phase shifting boss) changed from a monotonically decreasing curve to a flat U-shaped curve. The phase difference at both high and low frequencies was pulled back to around 90°. The phase difference change across the entire frequency band decreased from 22.5° to 14.7°, and the relative bandwidth that satisfies |Δφ-90°|≤±10° reached 11.1%.

[0096] contrast Figure 11 and Figure 13 It can be seen that the present invention compensates for the frequency dispersion of the inductive phase shift of the polarizer 2 by the capacitive phase shift of the phase shift protrusion 3, so that the phase difference-frequency curve changes from a monotonically decreasing curve to a flat U-shaped curve, and the relative bandwidth that satisfies |Δφ-90°|≤±10° increases from 7.2% to 11.1%, an increase of about 54%, which verifies the compensation effect of the phase shift protrusion on phase dispersion.

[0097] 3. Bandwidth and power capacity verification

[0098] 1) Bandwidth verification

[0099] According to the definition of relative bandwidth: Relative bandwidth = (f high -f low ) / f center × 100%, by scanning the axial ratio and voltage standing wave ratio across the entire frequency band using full-wave simulation (HFSS), the lower frequency bound f that simultaneously satisfies axial ratio ≤ 3dB and voltage standing wave ratio ≤ 1.5 is found. low and the upper frequency bound f high Simulation results show that f high =38GHz, f low =32GHz, f center =35GHz, calculated as: relative bandwidth = (f high -f low ) / f center × 100% = (38-32) / 35 = 17.1. This simulation result has fully verified that the present invention has wideband operation capability in the Ka band.

[0100] 2) Peak power capacity verification

[0101] This invention features an all-metal structure with no dielectric material, thus eliminating the problem of dielectric breakdown. The peak power capacity is determined by the electric field strength on the metal surface. The aperture dimensions are 590mm × 590mm (area A ≈ 0.35m²). 2 The power density corresponding to a peak power of 200kW is approximately 570kW / m³. 2 Based on the relationship between power density and electric field strength, the electric field strength E≈ ≈2.1×10 4V / m, far below the air breakdown field strength under standard atmospheric pressure (approximately 3 × 10⁻⁶ m). 6 With sufficient margin (V / m), the risk of air breakdown at a peak power of 200kW is extremely low, and the peak power capacity meets the requirement of ≥200kW.

[0102] 3) Average power capacity verification

[0103] This invention employs an all-metal structure, where insertion loss is primarily determined by conductor ohmic loss. The surface resistivity of brass in the Ka band is approximately 0.1~0.15Ω, and simulation calculations show that the insertion loss of this invention is <0.2dB across the entire frequency band. Under a 20kW continuous wave input condition, the power loss is approximately 900W. This approximately 900W power loss is distributed across a 590mm×590mm diameter metal structure, effectively dissipating heat through natural convection and radiation. The metal structure (brass) has high thermal conductivity (approximately 120W / (m·K)), allowing heat to be rapidly conducted to the frame 1 and dissipated through convection, resulting in controllable temperature rise. Simultaneously, the elastic tensioning mechanism 6 ensures the straightness of the polarization plate 2 along its entire length, resulting in a uniform electric field distribution and preventing localized field concentration and hotspot formation caused by grid bending or thermal deformation, thus structurally guaranteeing the reliability of the average power capacity.

[0104] 4. Environmental adaptability verification

[0105] This invention uses the continuous tension of the elastic tensioning mechanism 6 to keep the thin and narrow polarization plate 2 straight at all times. Under temperature cycling conditions (-40℃ to +70℃), the continuous tension of the elastic tensioning mechanism 6 keeps the polarization plate 2 straight along its entire length, effectively avoiding phase errors caused by the bending deformation of the grid bars due to their own gravity; the elastic deformation of the spring steel wire 61 can adaptively compensate for thermal expansion and contraction caused by temperature changes and deformation caused by the force on the frame 1, ensuring that the relative positional accuracy between each polarization plate 2 remains stable during operation, significantly improving the environmental adaptability of the circular polarizer.

[0106] In summary, this invention effectively solves the technical problems of limited bandwidth, difficulty in controlling grid deformation, and insufficient environmental adaptability of existing grid-type circular polarizers in Ka-band applications. It has outstanding advantages such as wide bandwidth (relative bandwidth ≥16%), large power capacity (20kW average power / 200kW peak power), high precision, and high reliability.

[0107] The above description is merely a specific embodiment of the present invention, intended to enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments without creative effort will be readily apparent to those skilled in the art; the basic principles defined herein can be applied to other embodiments without departing from the spirit and scope of the present invention.

[0108] It should be understood that this invention is not limited to the specific content described above, and various equivalent modifications or substitutions can be made without departing from its scope of protection. The scope of protection of this invention is defined only by the appended claims.

Claims

1. A Ka-band broadband high-power grid-strip circular polarizer, characterized in that, include: The frame (1) is made of rigid materials and forms the load-bearing frame of the circular polarizer; Multiple polarization plates (2), each of the polarization plates (2) is a long strip of conductive metal sheet, each of the polarization plates (2) is arranged in parallel and spaced apart in the frame (1), one end of each polarization plate (2) is a fixed end and the other end is a free end; Phase-tuning protrusions (3): Multiple phase-tuning protrusions (3) are integrally formed on the body of each polarization plate (2). The phase-tuning protrusions (3) are used to provide capacitive phase shift to compensate for the inductive phase shift frequency dispersion of the polarization plate (2). A polarization plate positioning block (4) is fixedly set on the frame (1), and each polarization plate (2) is inserted into the polarization plate positioning block (4). The polarization plate positioning block (4) is used to constrain the position of each polarization plate (2) in the width direction and thickness direction, and to maintain the degree of freedom in the length direction of each polarization plate (2). Locking member (5) is provided on the frame (1) and connected to the fixed end of each polarization plate (2) for limiting and fixing the fixed end of each polarization plate (2) on the frame (1); An elastic tensioning mechanism (6) is disposed on the frame (1) and connected to the free end of each polarization sheet (2), for applying a continuous tension to each polarization sheet (2) to keep each polarization sheet in a straight state.

2. The Ka-band broadband high-power grid-strip circular polarizer according to claim 1, characterized in that, The frame (1) is made of channel steel and diagonal bracing fastened together with screws.

3. The Ka-band broadband high-power grid-strip circular polarizer according to claim 1, characterized in that, The polarizer (2) is made of brass.

4. The Ka-band broadband high-power grid-strip circular polarizer according to claim 1, characterized in that, The polarization plate (2) has a double-layer grid structure.

5. The Ka-band broadband high-power grid-strip circular polarizer according to claim 1, characterized in that, The phase-adjusting boss (3) is a cylindrical boss, and each of the phase-adjusting bosses (3) is arranged in an array along the length direction on the body of the polarization plate (2).

6. The Ka-band broadband high-power grid-strip circular polarizer according to claim 5, characterized in that, Each of the polarization plates (2) is symmetrically provided with the phase adjustment boss (3) on both the front and back sides.

7. The Ka-band broadband high-power grid-strip circular polarizer according to claim 1, characterized in that, The locking component (5) is a locking post. The surface of the locking post is provided with an annular groove. Each polarization plate (2) has a locking hole at its fixed end. The locking post passes through each locking hole, and the edge of each locking hole is embedded in the annular groove. Both ends of the locking post are limited to the frame (1).

8. The Ka-band broadband high-power grid-strip circular polarizer according to claim 1, characterized in that, The elastic tensioning mechanism (6) includes a spring steel wire (61), a T-shaped steel block (62), and a fixed steel column (63). The spring steel wire (61) is bent and threaded through the frame (1). The T-shaped steel block (62) is connected to the spring steel wire (61). The fixed steel column (63) is set on the T-shaped steel block (62). The free end of each polarization plate (2) is sleeved on the fixed steel column (63). The elastic restoring force of the spring steel wire (61) is transmitted to each polarization plate (2) through the T-shaped steel block (62) and the fixed steel column (63) to form the continuous tension.

9. The Ka-band broadband high-power grid-strip circular polarizer according to claim 8, characterized in that, The fixed steel column (63) is provided with an annular groove, and each polarization plate (2) has a through hole at its free end. The through hole is sleeved on the fixed steel column (63), and the edge of the through hole is embedded in the annular groove.

10. A method for designing and manufacturing a Ka-band broadband high-power grid-strip circular polarizer, characterized in that, Includes the following steps: Step 1: Based on the electrical performance requirements of the target operating frequency band, determine the thickness of each polarization plate (2) through simulation optimization. The spacing between adjacent polarization plates (2) and the longitudinal distance between two adjacent polarization plates , so that the determined thickness ,spacing and longitudinal distance The electrical performance requirements of the target operating frequency band must be met. Step 2: Provide a frame (1) to connect rigid materials into a square frame structure, which serves as the load-bearing frame of the circular polarizer; Step 3: Provide multiple polarization plates (2), each of the polarization plates (2) is a strip-shaped conductive metal sheet, and multiple phase adjustment protrusions (3) are integrally formed on the sheet of each polarization plate (2). Step 4: Fix the polarization plate positioning block (4) on the frame (1), and pass each polarization plate (2) through the polarization plate positioning block (4) in parallel and at intervals, so that the polarization plate positioning block (4) constrains the position of each polarization plate (2) in the width and thickness directions, and maintains the degree of freedom in the length direction of each polarization plate (2); Step 5: Define one end of each polarization sheet (2) as a fixed end and the other end as a free end. Set the locking member (5) on the frame (1) and connect it to the fixed end of each polarization sheet (2). The locking member (5) limits and fixes the fixed end of each polarization sheet (2) to the frame (1). Step 6: Set the elastic tensioning mechanism (6) on the frame (1) and connect it to the free end of each polarized sheet (2). The elastic tensioning mechanism (6) includes a spring steel wire (61), a T-shaped steel block (62) and a fixed steel column (63). The spring steel wire (61) is bent and threaded through the frame (1). The T-shaped steel block (62) is connected to the spring steel wire (61). The fixed steel column (63) is set on the T-shaped steel block (62). The free end of each polarized sheet (2) is sleeved on the fixed steel column (63). The spring steel wire (61) generates an elastic restoring force. The elastic restoring force is transmitted to each polarized sheet (2) through the T-shaped steel block (62) and the fixed steel column (63). A continuous tension along the length direction is applied to each polarized sheet (2) to keep each polarized sheet (2) in a straight state.

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