An ultra-low profile high-gain circularly polarized folded transmission array antenna with low radar cross section

Abstract

The application discloses a kind of ultra-low profile high-gain circularly polarized folded transmission array antennas with low radar scattering cross section, including the chessboard type arrangement of PCM array, transmission array, reflecting array and feed horn;The chessboard type arrangement of PCM array is placed on transmission array, and the two are separated by air layer 1;The transmission array is placed on reflecting array, and the two are separated by air layer 2;The reflecting array center opens a rectangular hole, and the feed horn is placed in the rectangular hole and embedded.The folded transmission array antenna of the application has the wideband high-gain circularly polarized radiation performance, and the radar scattering cross section reduction of out-of-band double frequency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of antennas, and particularly relates to a low-radar-scattering cross-section ultra-low-profile high-gain circularly polarized folded transmission array antenna. BACKGROUND

[0002] The folded transmission array antenna is a high-gain high-efficiency planar array antenna, has the characteristics of low spatial feed loss, flexible planar array element phase control, easy integration with a platform and a system, and convenient manufacturing and low cost, and has extremely important applications in military communication and detection systems with limited space and stealth requirements.

[0003] In information network military systems, such as long-range radars, short-wave high-sensitivity sensing systems, and long-range wireless communication, high-gain antennas are important components. Meanwhile, with the development of modern electronic countermeasure technology, radar stealth has become another key requirement of detection systems. Therefore, radar stealth technology and electromagnetic protection measures should be used in detection systems. In addition, due to the strict space limitation of detection platforms, there is an urgent need for high-efficiency low-profile antennas.

[0004] Although the folded transmission array antenna has a relatively low profile, its profile is still high for some specific demand small-size antenna detection platforms. The traditional technology for realizing out-of-band dual-frequency radar scattering cross-section reduction has a high profile and a complex structure. SUMMARY

[0005] The application aims to provide a low-radar-scattering cross-section ultra-low-profile high-gain circularly polarized folded transmission array antenna.

[0006] The technical solution of the application is as follows: a low-radar-scattering cross-section ultra-low-profile high-gain circularly polarized folded transmission array antenna, comprising a chessboard-type PCM array, a transmission array, a reflection array, and a feed horn; the chessboard-type PCM array is placed above the transmission array, and the two are separated by an air layer 1; the transmission array is placed above the reflection array, and the two are separated by an air layer 2; the reflection array is centrally provided with a rectangular hole, and the feed horn is embedded in the rectangular hole.

[0007] Further, the PCM array is composed of PCM units and mirror image units, the PCM unit is composed of a bidirectional arrow patch 1 and a dielectric layer 1, the mirror image unit is obtained by rotating the PCM unit by 90 degrees around a center point, the PCM units are arranged in the upper left part and the lower right part of the array, and the mirror image units are arranged in the lower left part and the upper right part of the array.

[0008] Further, the transmission array is composed of transmission units of R-T structure, which is composed of a transmission layer, an intermediate layer, a receiving layer and a metal through hole. The transmission layer is composed of a U-shaped cut corner patch with truncated square split ring and a dielectric layer 2, which is located at the topmost position. The transmission layer patch is phase-adjusted by rotation. The intermediate layer is composed of a thin metal layer with a circular hole in the center and a dielectric layer 3, which is located in the middle. The thin metal layer is used to isolate the transmission layer and the receiving layer, and the dielectric layer 3 is used to connect the transmission layer and the receiving layer. The receiving layer is composed of a U-shaped cut patch with square split ring and a dielectric layer 4, which is located at the bottommost position. The metal through hole penetrates the transmission layer, the intermediate layer and the receiving layer, and connects the transmission layer patch and the receiving layer patch.

[0009] Further, the reflection array is composed of phase-adjustable reflection units, which are composed of bidirectional arrow patch 2 and dielectric layer 5. The size of the bidirectional arrow unit changes according to the phase adjustment requirement.

[0010] Further, the PCM unit of the PCM array has the same period size as the transmission unit of the transmission array, and the center projections of the two in the vertical direction coincide. The reflection unit of the reflection array is half the period size of the transmission unit of the transmission array. One transmission unit can cover four reflection units, and the projections of the transmission unit and the four reflection units coincide in the vertical direction.

[0011] Further, the feed horn is a corner horn, and three layers of metal shell are added to embed the center of the reflection array.

[0012] Further, the height of the air layer 1 is h1=12.3mm, the material of the dielectric layer 1 is F4BM220, the thickness is 0.43mm, the dielectric constant is 2.2, and the dielectric loss angle is 0.0015.

[0013] Further, the height of the air layer 2 is h2=67.2mm, the material of the dielectric layer 2 and the dielectric layer 4 is F4BM350, the thickness is 2mm, the dielectric constant is 3.48, and the dielectric loss angle is 0.003. The material of the dielectric layer 3 is RO4450F, the thickness is 0.1mm, the dielectric constant is 3.52, and the dielectric loss angle is 0.0041.

[0014] Further, the size of the rectangular hole is 43.8mm×36mm, the material of the dielectric layer 5 is F4BM350, the thickness is 3mm, the dielectric constant is 3.48, and the dielectric loss angle is 0.003.

[0015] Further, the transmission array and the reflection array simultaneously perform phase modulation, that is, a double-sided phase modulation method, under the condition of a low profile, the transmission array compensates for the path loss of the electromagnetic wave to generate a plane wave to achieve high gain, and the reflection array lengthens the equivalent focal point of the folded transmission array to obtain a larger focal length, as follows:

[0016] The transmission array compensates for the phase difference between the equivalent feed source and the different transmission units and the center transmission unit, and the phase compensation formula of the mth transmission unit is as follows:

[0017]

[0018] Where k0 is a free space constant, x mn and y mn are the x-axis distance and y-axis distance of the unit from the center unit, F is the focal length size, is the phase of the center unit;

[0019] The reflection array compensates for the phase anomaly caused by the reduction of the profile, and the phase compensation formula of the mth reflection unit is as follows:

[0020]

[0021] Where the front half of the right side of the equation represents the phase before the electromagnetic wave reaches the reflection array, the rear half of the right side of the equation represents the phase after the electromagnetic wave is compensated, and F2 is the equivalent focal length of the electromagnetic wave at the reflection array after compensation;

[0022] When double-sided phase modulation is performed, the feed source first emits an x-polarized wave to the transmission array, at this time the x-polarized wave is reflected by the transmission array and is emitted to the reflection array, the x-polarized wave is lengthened after compensation at the reflection array, and is converted into a y-polarized wave, when the y-polarized wave is emitted to the transmission array again, it can be received by the transmission array and converted into a right circularly polarized wave, and compensation is simultaneously achieved.

[0023] Compared with the prior art, the present application has the following advantages: 1) The folded transmission array antenna of the present application has a wideband high-gain circularly polarized radiation performance. 2) The present application adopts a double-sided phase modulation method to reduce the profile of the antenna. 3) The present application adopts a special size of a chessboard type PCM array to achieve a double-band wideband RCS reduction. 4) The present application decouples the transmission array and the chessboard type PCM array, so that the excess frequency band also has a certain RCS reduction. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The present application is a low radar scattering cross section (RCS) ultra-low profile high gain circularly polarized folded transmission array antenna profile diagram.

[0025] Figure 2Simulation diagram of the ultra-low profile high-gain circularly polarized folded transmission array antenna with low radar cross section of the present application.

[0026] Figure 3 Three-dimensional diagram of the corresponding positions of the PCM unit, the transmission unit and the reflection unit of the present application.

[0027] Figure 4 Patch diagram of the present application.

[0028] Figure 5 Patch layer diagram of the transmission unit, wherein (a) is the patch diagram of the transmission layer and (b) is the patch diagram of the receiving layer unit.

[0029] Figure 6 Reflection performance diagram of the PCM unit.

[0030] Figure 7 Transmission performance diagram of the transmission unit without truncation.

[0031] Figure 8 Reflection performance diagram of the combination of the PCM unit and the transmission unit.

[0032] Figure 9 Transmission performance diagram of the combination of the PCM unit and the transmission unit after taking truncation measures.

[0033] Figure 10 Three-dimensional view of the reflection unit of the present application.

[0034] Figure 11 Three views of the horn feed source of the present application.

[0035] Figure 12 S parameter diagram of the measurement and simulation of the antenna of the present application.

[0036] Figure 13 Gain diagram of the measurement and simulation of the antenna of the present application.

[0037] Figure 14 Diagram of the measurement and simulation of the antenna of the present application at 9.9 GHz Phi=0°.

[0038] Figure 15 Diagram of the measurement and simulation of the antenna of the present application at 9.9 GHz Phi=90°.

[0039] Figure 16 RCS diagram of the measurement and simulation of the antenna of the present application minus the ground. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0041] The present application proposes to further reduce the profile of the folded transmission array antenna by using a double-sided phase modulation method, and designs a chessboard array PCM array which can realize double-frequency RCS reduction by using only a single-layer structure.

[0042] In combination Figure 1 , the low-radar scattering cross-section, ultra-low profile, high-gain circularly polarized folded transmission array antenna includes a chessboard array PCM array 1, a transmission array 2, a reflection array 3, and a feed horn 4. The chessboard array PCM array 1 is placed above the transmission array 2 and separated by an air layer 1. The transmission array 2 is placed above the reflection array 3 and separated by an air layer 2. The reflection array 3 has a rectangular hole in the center, and the feed horn 4 is embedded in the rectangular hole.

[0043] The PCM array 1 is composed of PCM units and their mirror units, which are obtained by rotating the PCM units by 90° around the center point. The PCM array is arranged in a chessboard pattern: the PCM units are arranged in the upper left and lower right parts of the array, and the mirror units are arranged in the lower left and upper right parts of the array. Through the chessboard arrangement of the PCM units and their mirror units, the scattering energy can be redirected to a 45° plane different from the incident direction, thereby realizing RCS reduction in the incident direction of the antenna.

[0044] The double-sided phase modulation method is used to simultaneously modulate the transmission array 2 and the reflection array 3. Under the condition of low profile, the transmission array modulation can compensate for the path loss of electromagnetic waves to produce a plane wave and achieve high gain, and the reflection array modulation can lengthen the equivalent focal point of the folded transmission array to obtain a larger focal length.

[0045] Further, the transmission array 2 is mainly responsible for compensating for the phase difference between the equivalent feed and the distance between different transmission units and the center transmission unit, so the phase compensation formula of the mth transmission unit is:

[0046]

[0047] where k0 is the free space constant, x mn and y mn are the x-axis and y-axis distances of the unit from the center unit, F is the focal length size, and the phase of the center unit.

[0048] Further, the reflection array 3 mainly compensates for the phase anomaly caused by the reduction of the profile, so the phase compensation formula of the mth reflection unit is:

[0049]

[0050] Wherein the left part of the minus sign on the right side of the equation represents the phase of the electromagnetic wave before the phase compensation when it reaches the reflecting array, and the right part of the minus sign on the right side of the equation represents the phase of the electromagnetic wave after the phase compensation. F2 is the equivalent focal length of the electromagnetic wave at the reflecting array after the phase compensation.

[0051] When the phase is adjusted on both sides, the feed will first emit x-polarized waves to the transmitting array. At this time, the x-polarized waves will be reflected by the transmitting array and then be emitted to the reflecting array. After the x-polarized waves are compensated at the reflecting array, the equivalent focal length of the antenna is lengthened, and the polarization is converted to y-polarized waves. When the y-polarized waves are emitted to the transmitting array again, they can be received by the transmitting array and converted into right-handed circularly polarized waves, and at the same time, the phase compensation is realized to generate high-gain radiation.

[0052] The PCM unit is composed of a bidirectional arrow patch 1 and a dielectric layer 1, the bidirectional arrow patch 1 is composed of a bevel patch and a double-L-shaped patch, the size of the bevel patch can control the polarization conversion performance of the low-frequency out-of-band, and the size of the double-L-shaped patch can control the polarization conversion performance of the high-frequency out-of-band.

[0053] The transmitting array 2 is composed of transmitting units of R-T structure, the transmitting unit is composed of a transmitting layer, an intermediate layer, a receiving layer and a metal through hole. The transmitting layer is composed of a U-shaped cut corner patch with a truncated square split ring and a dielectric layer 2, and is located at the uppermost position. The transmitting layer patch can be phase-adjusted by rotation. The intermediate layer is composed of a thin metal layer with a circular hole in the center and a dielectric layer 3, and is located in the middle. The thin metal layer is used to isolate the transmitting layer and the receiving layer, and the dielectric layer 3 is used to connect the transmitting layer and the receiving layer. The receiving layer is composed of a U-shaped cut patch with a square split ring and a dielectric layer 4, and is located at the lowermost position. The metal through hole penetrates the transmitting layer, the intermediate layer and the receiving layer, and connects the transmitting layer patch and the receiving layer patch.

[0054] The transmitting layer patch is composed of a U-shaped cut corner square structure and a square split ring. The U-shaped cut can increase the low-frequency bandwidth of the patch, and the square split ring can increase the high-frequency bandwidth of the patch and achieve good high-frequency out-of-band suppression characteristics.

[0055] Further, at the four endpoints of the square split ring of the transmitting layer patch of the transmitting unit, a cut of length k is implemented in the x-axis direction and the y-axis direction respectively at a distance of m. The cut can reduce the coupling of the PCM unit and the transmitting unit in the reflection performance at high frequencies.

[0056] The reflecting array 3 is composed of phase-adjustable reflecting units, the reflecting unit is composed of a bidirectional arrow patch 2 and a dielectric layer 5, and the size of the bidirectional arrow patch 2 will change accordingly according to the phase adjustment requirement.

[0057] In combination Figure 3 , the PCM unit and the transmissive unit have the same period size, and the projections of the centers of the two units coincide in the vertical direction. The reflective unit of the reflective array has a period size of half of the transmissive unit of the transmissive array, the area of a single transmissive unit can cover four reflective units, and the projections of the transmissive unit and the four reflective units coincide in the vertical direction. The PCM unit, the transmissive unit, and the reflective unit are arranged in this order from top to bottom.

[0058] The feed horn 4 is a corner horn, and three layers of metal shells are added to embed the center of the reflective array.

[0059] Embodiment

[0060] In order to verify the effectiveness of the scheme of the present application, the following experimental design is carried out.

[0061] In combination Figure 1 , the height h1 of the air layer 1 is 12.3 mm, the material of the dielectric layer 1 is F4BM220, the thickness is 0.43 mm, the dielectric constant is 2.2, and the dielectric loss angle is 0.0015.

[0062] The height h2 of the air layer 2 is 48.3 mm, the materials of the dielectric layer 2 and the dielectric layer 4 are F4BM350, the thickness is 2 mm, the dielectric constant is 3.48, and the dielectric loss angle is 0.003. The material of the dielectric layer 3 is RO4450F, the thickness is 0.1 mm, the dielectric constant is 3.52, and the dielectric loss angle is 0.0041.

[0063] The rectangular hole size is 43.8 mm x 36 mm, the material of the dielectric layer 5 is F4BM350, the thickness is 3 mm, the dielectric constant is 3.48, and the dielectric loss angle is 0.003.

[0064] Figure 2 It is a simulation diagram of the antenna of the present embodiment. The transmissive unit and the PCM unit have a total of 24 x 24 units, the reflective unit has a total of 48 x 48 units, and the aperture size of the antenna is 336 mm x 336 mm. The F / D value is 1, and the profile height is designed as F / 5, i.e. 67.2 mm.

[0065] In combination Figure 3 , the period of the PCM unit and the transmissive unit is 14 mm, and the projections of the centers of the two units coincide in the vertical direction. The period size of the reflective unit is 7 mm, the area of a single transmissive unit can cover four reflective units, and the projections of the transmissive unit and the four reflective units coincide in the vertical direction. The PCM unit, the transmissive unit, and the reflective unit are arranged in this order from top to bottom.

[0066] Figure 4The bidirectional arrow patch 1 is composed of a bevel patch and a double L-shaped patch. The bevel patch can realize the polarization conversion performance of low frequency out of band, and the double L-shaped patch can realize the polarization conversion performance of high frequency out of band. The parameters of the bidirectional arrow patch 1 are as follows: a1=4.82, l 10 =13, w1=0.6, w2=0.5.

[0067] The transmission unit is composed of a transmission layer, an intermediate layer, a receiving layer and a metal through hole. The transmission layer is composed of a U-shaped cut corner patch with a truncated square split ring and a dielectric layer 2, and is located at the uppermost. The transmission layer patch can be phase-modulated by rotation, and the rotation angle is the phase-modulation angle. The intermediate layer is composed of a thin metal layer with a circular hole in the center and a dielectric layer 3, and is located in the middle. The diameter of the circular hole is 1.8 mm, and the thickness of the thin metal layer is 0.1 mm. The thin metal layer is used to isolate the transmission layer and the receiving layer, and the dielectric layer 3 is used to connect the transmission layer and the receiving layer. The receiving layer is composed of a U-shaped cut patch with a square split ring and a dielectric layer 4, and is located at the lowermost. The metal through hole penetrates the transmission layer, the intermediate layer and the receiving layer, and connects the transmission layer patch and the receiving layer patch. The diameter of the metal through hole is 0.6 mm.

[0068] Figure 5 (a) is the transmission layer patch, which is composed of a U-shaped cut corner square structure and a square split ring. The U-shaped cut can increase the low frequency bandwidth of the patch, and the square split ring can increase the high frequency bandwidth of the patch and realize good high frequency out-of-band suppression characteristics. The size of the cut corner is 1.9 mm.

[0069] At the four endpoints of the square split ring of the transmission layer patch of the transmission unit, a cut of length k=0.4 mm is implemented at a distance of m=0.6 mm along the x-axis direction and the y-axis direction, respectively. The cut can reduce the coupling of the PCM unit and the transmission unit in high frequency reflection performance.

[0070] Figure 5 (b) is the receiving layer patch, which has a similar shape to the transmission layer patch, but without cut and without cut corner.

[0071] The parameters of the receiving layer patch are as follows: L1=9, L2=6.4, L3=4, L5=2.4, q2=1, q3=1.2, and p=14. Wherein, p is the period of the unit.

[0072] The PCM unit and the transmission unit are integrated, which is referred to as integrated unit hereinafter. The integrated unit can realize the polarization conversion performance of high and low frequency out of band, and the in-band radiation performance does not decrease too much.

[0073] Figure 6The reflection performance of the PCM unit is shown in the figure. The single-layer PCM unit is loaded on the metal ground with an air gap of 12.3 mm in height between the metal ground and the PCM unit, and the single-layer PCM unit can achieve a polarization conversion performance of more than -1 dB in the low-frequency band of 2.85-7.93 GHz and the high-frequency band of 12.34-16.26 GHz, and has no polarization conversion performance in the passband of 8-12 GHz. Moreover, the Rxy curve of the PCM unit has a steep change in the transition band of the polarization conversion to the non-polarization conversion, i.e., the adjacent frequency bands with 8 GHz and 12 GHz as the center frequency points. The good passband edge selectivity enables the PCM and the radiation unit to effectively reduce the gap between the radiation frequency band and the RCS reduction frequency band when the PCM and the radiation unit are combined to achieve low-RCS high-gain radiation.

[0074] The size of the bevel patch can control the polarization conversion performance of the PCM unit at low frequencies outside the band, and the size of the double-L-shaped patch can control the polarization conversion performance of the PCM unit at high frequencies outside the band. The bevel patch and the double-L-shaped patch are approximately perpendicular in position, and thus the polarization conversion effects cancel each other out in the passband of 8-12 GHz, achieving the non-polarization conversion performance in the passband.

[0075] Figure 7 The transmission performance of the transmission unit without truncation is shown in the figure. The transmission amplitude of the unit reaches 0.96 around the center frequency of 10 GHz, achieving a high transmission conversion rate. In the frequency band of 8.38-12.38 GHz, the transmission amplitude is maintained to be greater than 0.8. In the edge region of the passband, i.e., the adjacent frequency bands with 8.3 GHz and 12.4 GHz as the center frequency points, the amplitude curve changes very steeply, and the unit exhibits good out-of-band suppression characteristics and passband edge selectivity. The steep edge characteristics of the transmission unit make it not coupled too much when combined with the scattering cancellation metasurface, which is conducive to eliminating the gap between the antenna radiation frequency band and the RCS reduction frequency band.

[0076] Figure 8 The reflection performance of the PCM unit and the transmission unit after integration and truncation is shown in the figure. In the integration, the thin metal layer in the middle layer of the transmission unit provides a metal ground for the PCM unit; and in order to achieve the decoupling of the PCM unit and the transmission unit in the high-frequency reflection performance, the square split ring of the transmission layer patch of the transmission unit is truncated. The integrated unit has a polarization conversion performance of at least -1 dB in the frequency bands of 2.54 GHz-7.98 GHz and 12.38-16.63 GHz.

[0077] Figure 9 The transmission performance of the PCM unit and the transmission unit after integration and truncation is shown in the figure. The maximum transmission amplitude is 0.95, which is 0.1 lower than that of the relative transmission unit without truncation, and the gain of the antenna array is reduced. The amplitude of the unit is greater than 0.8 in the frequency band of 8.29 GHz-11.64 GHz.

[0078] Combining Figure 10 is a three-dimensional view of the reflecting unit, and its parameters are: p r = 7, h r = 3, a2= 3.2, l 20 = 4.6, w3= 0.6. When the phase of the reflecting unit is adjusted, the phase can be changed by changing the size of a2, and the smaller a2 is, the more phase the reflecting unit compensates.

[0079] Combining Figure 11 , the feed horn is a corner horn, and three layers of metal shells are added to embed the center of the reflecting array.

[0080] The corner horn feed uses a waveguide port with a size of 22.86mm x 10.16mm as input, and the horn aperture size is 31mm x 24mm. The first layer of rectangular shell is to embed into the reflecting array, so the thickness is consistent with the reflecting array medium thickness of 3mm, and the aperture size is 32mm x 40mm. The second layer of rectangular shell is to fix the whole feed with the reflecting array, so its size is larger than the first layer of rectangular shell, which is 45mm x 45mm, and the thickness is also 3mm. And four circular holes are punched around it, which is convenient for fixing to the medium layer of the reflecting array with screws. The third rectangular shell is to facilitate processing and easy assembly of the horn feed and waveguide-to-coaxial structure, so its size is consistent with the flange plate of the waveguide-to-coaxial structure, which is 34mm x 34mm, and the thickness is 22.2mm.

[0081] Figure 12 is the S parameter diagram of antenna measurement and simulation, the antenna has very high impedance matching near 10GHz, and the S 11 is close to -10dB in the radiation band of 8.5GHz-12.5GHz.

[0082] Figure 13 is the gain axial ratio diagram of antenna measurement and simulation, the antenna realizes the maximum gain of 27.52dBic at 9.9GHz, and the aperture efficiency is 35.6%. In addition, the 3dB gain bandwidth is 21.9%(8.9GHz-11.1GHz), and the 3dB axial ratio bandwidth is 28.5%(8.4GHz-11.2GHz).

[0083] Figure 14 is the 9.9GHz φ=0° directional diagram of antenna measurement and simulation, the main polarization main lobe gain is 27.52dBic, the cross polarization main lobe gain is 5.3dBic, and the main polarization side lobe is -17.5dB.

[0084] Figure 15For the antenna measurement and simulation of the 9.9GHz φ=90° pattern, the main polarization main lobe gain is 27.52dBic, the cross polarization main lobe gain is 5.1dBic, and the main polarization side lobe is -14.9dB.

[0085] Figure 16 For the antenna measurement and simulation of the RCS subtracted from the ground under different polarized wave incidence. The antenna realizes at least 10dB RCS reduction in the out-of-band 3.24GHz-7.53GHz and 13.2GHz-16.42GHz. And the RCS reduction size is basically unchanged under the incidence of 45° polarized wave, x polarized wave and y polarized wave. Because the transmitting antenna and the receiving antenna cannot coincide during the antenna measurement, there is a 4.2° angle between the two, so the RCS measurement value of the high frequency out-of-band part is higher than the simulation value.

[0086] The antenna also has considerable RCS reduction in its own radiation frequency band, and the RCS has slight differences when the polarization of the incident wave is different. The antenna has at least 10dB RCS reduction in 9.4GHz-10.23GHz, because the transmission unit of the FTA is rotated for phase compensation, and the transmission unit with different rotation angles has different phase shift effects on the incident wave, so that the scattering energy can also be scattered in different directions. The antenna as a whole has certain RCS reduction capability in the full frequency band of 2.5GHz-17GHz.

[0087] In summary, the low-radar-scattering cross-section super-low-profile high-gain circularly polarized folded transmission array antenna of the application can realize high-gain wideband circularly polarized radiation in the band, and realize double-sideband radar scattering cross-section reduction out of the band by combining the specific polarization conversion bidirectional arrow unit of the chessboard type arrangement. The radiation part has the characteristics of plane and low profile, the radar scattering cross-section reduction part has the characteristics of double-sideband reduction, high transmission in the band, and simple structure without stacking.

[0088] The technical features of the above embodiments can be combined in any way. In order to make the description simple, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the present application.

[0089] The above-described embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the application. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are all within the protection scope of the application. Therefore, the protection scope of the application should be subject to the appended claims.

Claims

1. A low radar cross section, ultra-low profile, high gain circularly polarized folded transmissive array antenna with low profile, characterized in that, The PCM array (1) of chessboard arrangement, the transmission array (2), the reflection array (3) and the feed horn (4); the PCM array (1) of chessboard arrangement is placed above the transmission array (2), and the two are separated by a first air layer; the transmission array (2) is placed above the reflection array (3), and the two are separated by a second air layer; the reflection array (3) has a rectangular hole in the center, and the feed horn (4) is placed in the rectangular hole and embedded; The PCM array is composed of PCM units and their mirror units, the PCM unit is composed of a first bidirectional arrow patch and a first dielectric layer, the mirror unit is obtained by rotating the PCM unit by 90° around the center point, the PCM unit is arranged in the upper left part and the lower right part of the array, and the mirror unit is arranged in the lower left part and the upper right part of the array; The transmission array is composed of transmission units of R-T structure, the transmission unit is composed of a transmission layer, an intermediate layer, a receiving layer and a metal through hole, the transmission layer is composed of a U-shaped slit cut corner patch with truncated square split ring and a second dielectric layer, and is located at the uppermost, the transmission layer patch is phase-modulated by rotation; The intermediate layer is composed of a center thin metal layer with a circular hole and a third dielectric layer, and is located in the middle, the thin metal layer is used to isolate the transmission layer and the receiving layer, and the third dielectric layer is used to connect the transmission layer and the receiving layer; the receiving layer is composed of a U-shaped slit patch with square split ring and a fourth dielectric layer, and is located at the lowermost; the metal through hole penetrates the transmission layer, the intermediate layer and the receiving layer, and connects the transmission layer patch and the receiving layer patch; At the four endpoints of the square split ring of the transmission layer patch of the transmission unit, a truncation of length k is performed m away along the x-axis direction and the y-axis direction respectively.

2. The ultra-low profile high-gain circularly polarized folded transmitarray antenna with low radar cross section according to claim 1, characterized in that, The reflection array is composed of phase-adjustable reflection units, the reflection unit is composed of a second bidirectional arrow patch and a fifth dielectric layer, and the size of the second bidirectional arrow patch changes according to the phase modulation requirement.

3. The ultra-low profile high-gain circularly polarized folded transmitarray antenna with low radar cross section according to claim 1, characterized in that, The PCM unit of the PCM array and the transmission unit of the transmission array have the same period size, and the center projections of the two coincide in the vertical direction; the reflection unit of the reflection array is half the period size of the transmission unit of the transmission array, and the area of one transmission unit can cover four reflection units, and the projections of the transmission unit and the four reflection units coincide in the vertical direction.

4. The ultra-low profile high-gain circularly polarized folded transmitarray antenna with low radar cross section according to claim 1, characterized in that, The feed horn (4) is a corner horn, and three layers of metal shells are added to embed the center of the reflection array (3).

5. The ultra-low profile high-gain circularly polarized folded transmissive array antenna with low radar cross section of claim 1, wherein, The height of the first air layer h1=12.3mm, the material used for the first dielectric layer is F4BM220, the thickness is 0.43mm, the dielectric constant is 2.2, and the dielectric loss angle is 0.0015.

6. The ultra-low profile high-gain circularly polarized folded transmissive array antenna with low radar cross section of claim 1, wherein, The height of the second air layer h2=67.2mm, the materials used for the second dielectric layer and the fourth dielectric layer are F4BM350, the thickness is 2mm, the dielectric constant is 3.48, and the dielectric loss angle is 0.003, the material used for the third dielectric layer is RO4450F, the thickness is 0.1mm, the dielectric constant is 3.52, and the dielectric loss angle is 0.0041.

7. The ultra-low profile high-gain circularly polarized folded transmissive array antenna with low radar cross section of claim 2, wherein, The rectangular hole size is 43.8mm*36mm, the fifth medium layer uses F4BM350 as a material, the thickness is 3mm, the dielectric constant is 3.48, and the dielectric loss angle is 0.

003.

8. The ultra-low profile high-gain circularly polarized folded transmissive array antenna with low radar cross section of claim 1, wherein, The transmission array and the reflection array simultaneously perform phase modulation, that is, a double-sided phase modulation method, under the condition of a low profile, the transmission array compensates the path loss of the electromagnetic wave to generate a plane wave to realize high gain, and the reflection array lengthens the equivalent focal point of the folded transmission array to obtain a larger focal length, and the specific method is as follows: The transmission array compensates the phase difference generated by the distance between the equivalent feed source and different transmission units and the central transmission unit, and the phase compensation formula of the mn transmission unit is: where k0 is the free space constant, x mn and y mn are the x-axis and y-axis distances of a unit from a center unit, F is the focal length size, is the phase of the center unit; The reflection array compensates the phase anomaly caused by the profile reduction, and the phase compensation formula of the mn reflection unit is: Wherein the right half of the minus sign in the right end of the equation represents the phase before the electromagnetic wave reaches the reflection surface, the right half of the minus sign in the right end of the equation represents the phase after the electromagnetic wave is compensated, and F2 is the equivalent focal length of the electromagnetic wave at the reflection array after compensation; When double-sided phase modulation, the feed source will first emit x-polarized waves to the transmission array, at this time the x-polarized waves will be reflected by the transmission array and emitted to the reflection array, the x-polarized waves will lengthen the equivalent focal length of the antenna after compensation at the reflection array, and will be converted into y-polarized waves, when the y-polarized waves are emitted to the transmission array again, they can be received by the transmission array and converted into right-handed circularly polarized waves, while realizing compensation.

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