A compact reconfigurable transmission array beam scanning antenna

Abstract

The present invention discloses a compact, reconfigurable transmission array beam-scanning antenna, consisting of a rectangular feed horn loaded with a passive metalens and a small-scale electrically adjustable transmission array placed on its aperture. Compared with existing transmission array beam-scanning antennas, the present invention optimizes the electromagnetic field distribution on the feed aperture by customizing the rectangular horn and metalens structure, effectively reducing the distance between the transmission array and the aperture and significantly reducing the number of array elements and electrically tuned components used for beam scanning. Ultimately, beam scanning performance with a minimum elevation angle of ±30° and a maximum elevation angle of ±40° is achieved in eight azimuth directions: 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°. Therefore, it can be applied to low-cost, low-energy, and highly portable radar, satellite communications, mobile communications, and other scenarios.

Description

Technical Field

[0001] The present invention relates to the fields of novel artificial electromagnetic surface technology and beam scanning antenna, in particular to a compact reconfigurable transmission array beam scanning antenna. Background Art

[0002] In the field of optics, the concept of metalens provides a flat and ultrathin solution for wavefront and imaging. In the microwave field, negative refractive index metasurfaces, near-zero refractive index metasurfaces, Huygens metasurfaces, Fresnel zone plate lenses, and gradient refractive index (GRIN) metasurfaces are used in antenna design to seek gain improvement and beam steering.

[0003] Traditional reconfigurable transmission array beam scanning antennas (including arrays and feed horns) have a large system volume, mainly for the following reasons. In order to pursue excellent radiation performance, it is necessary to obtain plane wave excitation (i.e., uniform electromagnetic field amplitude and phase distribution) on the electrically adjustable transmission array. However, the electromagnetic wave on the aperture of an ordinary feed horn is a spherical wave. Therefore, the distance between the array and the aperture must be increased to allow the spherical wave to gradually transition to a quasi-plane wave, which undoubtedly increases the longitudinal size of the entire antenna system. Secondly, under conditions of a large array-feed distance, in order to reduce spillover loss and allow the array to intercept enough energy, a larger array scale and number of units are required, resulting in an increase in the lateral size of the entire system. In addition to the system volume issue, the electrically adjustable transmission array needs to integrate integrated tuning devices such as PIN diodes, varactor diodes or MEMS to achieve beam scanning functions. As the number of array units increases, the number of these devices also increases exponentially, which not only significantly increases the cost, but also increases the design difficulty due to its complex feed control network.

[0004] Miniaturization of electronic devices has always been a trend, and antennas are no exception. However, miniaturization of reconfigurable transmission array beam-scanning antennas is challenging. Blindly reducing the array-feed distance or array size can lead to a sharp deterioration in antenna performance, such as reduced gain and decreased beam-scanning performance.

[0005] In recent years, some research has focused on miniaturizing reconfigurable transmission array beam-scanning antennas. However, these antennas do not reshape the electromagnetic field on the feed horn surface, but instead directly reduce the array size and array-feed distance. While this reduces the overall size of the antenna system and the number of tuning components used, the performance of the beam-scanning antenna is significantly reduced. For example, the antenna's aperture efficiency decreases, the beam scanning direction is reduced, and the beam scanning elevation angle range is reduced. To maintain good antenna performance, the array elements must achieve large phase compensation, which significantly increases the design difficulty and phase control difficulty and cost of the elements. Summary of the Invention

[0006] Technical Problem: Against this backdrop, the present invention addresses the aforementioned challenges by providing a compact, reconfigurable transmission array beam-scanning antenna. This antenna system features a compact structure, a small overall size, and a minimal number of electrically tunable transmission array elements and tuning components, while still maintaining high performance in beam scanning range and aperture efficiency.

[0007] Technical solution: The present invention provides a compact reconfigurable transmission array beam scanning antenna, comprising a rectangular feed horn, a passive metalens placed inside the horn mouth of the rectangular feed horn, and an electrically adjustable transmission array placed on the outer surface of the passive metalens; wherein the front portion of the rectangular feed horn is a hollow large rectangle, and the rear portion is a hollow small rectangle, and the four corresponding faces of the large rectangle and the small rectangle are connected by trapezoidal plates to form a horn-shaped hollow body; the passive metalens is composed of 14 printed circuit boards and air layers alternately stacked; and the electrically adjustable transmission array (3) is composed of a plurality of transmission units arranged in a matrix.

[0008] The rectangular feed horn adjusts the structural dimensions based on the standard horn antenna, and extends its aperture along its normal direction. The passive super lens is placed in the extended portion to improve the electromagnetic field distribution on the aperture surface.

[0009] The passive superlens consists of 14 printed circuit boards and air layers stacked alternately. Each printed circuit board consists of 46×60 superlens units, and each unit contains the medium of the superlens unit and a square metal ring. Looking out from the inside of the speaker, the 14 printed circuit boards are divided into three layers, namely the first matching layer, the core layer, and the second matching layer. The first matching layer contains 3 printed circuit boards, the core layer contains 7 printed circuit boards, and the second matching layer contains 4 printed circuit boards. The metal of each printed circuit board faces outward, and the metal patterns on the 7 printed circuit boards in the first matching layer and the second matching layer are the same, and the metal patterns on the 7 printed circuit boards in the core layer are the same.

[0010] The thickness of the air layer between the printed circuit boards of the passive metalens is fixed, and the equivalent refractive index of the metalens unit depends on the outer square side length Ls of the square metal ring. The value range of Ls is: greater than the width w of the square metal ring and less than the width p of the medium of the metalens unit.

[0011] The electrically adjustable transmission array is composed of multiple electrically adjustable transmission units arranged in a matrix. The electrically adjustable transmission array is placed 10 mm outside the horn mouth of the rectangular feed horn and consists of 3×5 electrically adjustable transmission units. The electrically adjustable transmission units integrate 4 varactor diodes, using a total of 60 varactor diodes. The planar area of ​​the electrically adjustable transmission array is smaller than the planar area of ​​the horn aperture.

[0012] The electrically adjustable transmission array comprises, from the inside to the outside of the horn mouth, each electrically adjustable transmission unit including a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, and a third metal layer stacked in sequence. The first metal layer includes a receiving unit and a phase shifter. The receiving unit is composed of three rectangular metal patches arranged side by side, with a parasitic patch in the middle and rectangular patches on both sides. The two rectangular patches are connected by a thin metal wire. The midpoint of the metal wire is connected to the input end of the phase shifter. The receiving unit receives electromagnetic waves from the rectangular feed horn and feeds them into the phase shifter.

[0013] The phase shifter is composed of two cascaded orthogonal bridge-reflective phase shifters. Each orthogonal bridge-reflective phase shifter consists of a four-port directional coupler, two short-circuited microstrip lines, and two varactor diodes. The cathode of the varactor diode is respectively connected to the coupling port and the through port of the four-port directional coupler, and the anode is connected to the short-circuited microstrip line. The other end of each of the two short-circuited microstrip lines is connected to the second metal layer via a metal blind via.

[0014] The third metal layer is a radiation unit, consisting of a central rectangular patch and two peripheral U-shaped patches; a metal through-hole connects the output end of the phase shifter of the first metal layer and the central rectangular patch of the third metal layer, and is used to feed the phase-shifted signal into the radiation unit; the second metal layer is a fully covered metal, and there is a circular hole with a diameter larger than the aperture of the metal through-hole passing through the metal through-hole on the second metal layer, and the metal through-hole does not contact the second metal layer.

[0015] In the electrically tunable transmission array, the phase shifter on each transmission unit includes two orthogonal bridge reflective phase shifters, and each orthogonal bridge reflective phase shifter includes two varactor diodes. A DC bias line is drawn from the short-circuited microstrip line of the phase shifter and connected to a DC voltage controller via a 15 kilo-ohm resistor.

[0016] The four varactor diodes on each transmission unit are connected in parallel and controlled by the same reverse bias voltage. The phase of the electromagnetic wave passing through the 15 units on the electrically adjustable transmission array is controlled by 15 independent voltages. The phase shift value of the 15 units on the adjustable transmission array is precisely controlled by DC voltage to achieve beam scanning with a maximum elevation angle range of ±40° in eight azimuth directions with azimuth angles of 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°.

[0017] Beneficial effects: The compact reconfigurable transmission array beam scanning antenna of the present invention has the following advantages:

[0018] (1) According to existing literature, compared with existing antennas of the same type, the reconfigurable transmission array beam scanning antenna system in the present invention has the smallest volume, only 3.3λ0×2.6λ0×3.5λ0 (λ0 is the wavelength of the center frequency of the operating band), and the transmission array uses only 60 tuning elements, which has the advantages of compact structure and simple control network;

[0019] (2) Compared with existing antennas of the same type, the reconfigurable transmission array beam scanning antenna of the present invention has a small size, fewer array units, and fewer tuning elements, but still has a high forward radiation aperture efficiency and can achieve wide pitch angle beam scanning on the E plane, H plane, and 45° inclined plane, with good performance;

[0020] (3) The present invention is the first to load a metalens into the feed horn of a reconfigurable transmission array beam scanning antenna, achieving a planar wavefront on the horn mouth surface with uniform electromagnetic field amplitude and phase distribution, thereby significantly reducing the array-feed distance and eliminating the need for phase compensation in the array units, effectively reducing the system volume, array scale, and array design and control difficulty;

[0021] (4) The present invention can be prepared using mature mechanical processing, PCB processing technology and component surface mounting technology, and has the advantages of low processing difficulty and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The diagram is a three-dimensional structural diagram of a compact reconfigurable transmission array beam scanning antenna according to the present invention.

[0023] FIG2( a ) is a schematic diagram showing the principle of impedance matching of a gradient-index metalens in an embodiment of the present invention.

[0024] FIG2( b ) is a schematic structural diagram of a super lens unit in an embodiment of the present invention.

[0025] FIG2(c) shows the equivalent refractive index of the super lens unit according to the embodiment of the present invention as the side length L of the square ring increases. s changes.

[0026] Figure 2(d) shows the equivalent refractive index of the lens unit as L s The results obtained from the simulation process vary with the changes.

[0027] FIG3( a ) shows the refractive index distribution of the unit cells on the core layer and the matching layer of the metalens obtained by theoretical calculation in an embodiment of the present invention.

[0028] FIG3( b ) shows the side length L of the metal square ring of the unit on the core layer and matching layer of the metal lens obtained by theoretical calculation in an embodiment of the present invention. S distributed.

[0029] FIG3( c ) is a diagram showing the electric field distribution of the feed horn loaded with the actual super lens unit array on the xoz plane (left) and the yoz plane (right) obtained by simulation in an embodiment of the present invention.

[0030] FIG3( d ) is a near-field electric field distribution diagram obtained by testing at a distance of 10 mm from the horn mouth of the loaded superlens in an embodiment of the present invention. The left figure is the amplitude and the right figure is the phase.

[0031] FIG4( a ) is a schematic diagram of the three-dimensional structure of the transmission array unit in an embodiment of the present invention.

[0032] FIG4( b ) is a schematic diagram of the structure of each module of the transmission unit in an embodiment of the present invention.

[0033] FIG4( c ) shows the transmission phase and amplitude of the phase shifter obtained by simulation according to an embodiment of the present invention as the capacitance of the varactor diode changes.

[0034] FIG5( a ) is a physical picture of the matching layer dielectric plate, the core layer dielectric plate, and the assembled metalens of an embodiment of the present invention.

[0035] FIG5( b ) is a diagram showing the actual processing of the electrically adjustable transmission array according to an embodiment of the present invention.

[0036] FIG5(c) shows the variation of the transmission performance of the electrically adjustable transmission array with the DC voltage obtained by testing in an embodiment of the present invention.

[0037] FIG5(d) is a diagram of the test environment of the reconfigurable transmission array beam scanning antenna system according to an embodiment of the present invention.

[0038] FIG6( a ) is a test pattern of the E-plane, H-plane and 45° inclined plane at 5.4 GHz in an embodiment of the present invention.

[0039] FIG6( b ) is a test pattern of the E-plane, H-plane and 45° inclined plane at 5.45 GHz in an embodiment of the present invention.

[0040] FIG6( c ) is a test pattern of the E-plane, H-plane and 45° inclined plane at 5.55 GHz in an embodiment of the present invention.

[0041] FIG6( d ) is a reflection coefficient test result of the input port of the reconfigurable transmission array beam scanning antenna according to an embodiment of the present invention.

[0042] Among them are a rectangular feed horn 1, a passive metalens 2, a medium 21 of a metalens unit, a square metal ring 22, a first matching layer 23, a core layer 24, a second matching layer 25, a metalens unit 26, an electrically adjustable transmission array 3, an electrically adjustable transmission unit 33, a metal through-hole 31, a metal blind hole 32, a receiving unit 4, a parasitic patch 41, a rectangular patch 42, a metal wire 43, a phase shifter 5, an orthogonal bridge reflective phase shifter 51, a short-circuited microstrip line 52, a varactor diode 53, a four-port directional coupler 54, a 15 kilo-ohm resistor 55, a DC bias line 56, a radiating unit 6, a central rectangular patch 61, and a U-shaped patch 62. DETAILED DESCRIPTION

[0043] The present invention provides a compact reconfigurable transmission array beam scanning antenna, the three-dimensional structure of which is as follows Figure 1 As shown, the system comprises a rectangular feed horn 1, a passive metalens 2 placed inside the mouth of the rectangular feed horn 1, and an electrically adjustable transmission array 3 placed on the outer surface of the passive metalens 2. The front of the rectangular feed horn 1 is a large hollow rectangle, and the rear is a small hollow rectangle. The four corresponding faces of the large and small rectangles are connected by trapezoidal plates, forming a hollow horn-shaped body. The passive metalens 2 is composed of 14 printed circuit boards and air layers stacked alternately. The electrically adjustable transmission array 3 is composed of multiple transmission units arranged in a matrix. The beam steering method of the novel compact reconfigurable transmission array beam scanning antenna system of the present invention consists of a three-step wavefront shaping: first, the electromagnetic field amplitude distribution is adjusted by customizing the mouth surface structure; then, the passive metalens is used to reshape the phase and amplitude distribution of the near-field electric field into a plane wavefront; finally, phase adjustment and beam scanning are achieved through a small-scale electrically adjustable transmission array. Because the electromagnetic field energy is concentrated within a smaller area by the metalens, only a relatively small number of elements are required to construct the transmission array (i.e., 3 × 5 elements). Furthermore, since the outgoing wave from the feed aperture is a plane wavefront, the transmission array can be placed very close to the lens. This transmission array requires only 60 varactors as control elements, greatly simplifying the control network. The entire beam-scanning antenna system measures only 3.3λ0 × 2.6λ0 × 3.5λ0 (including the horn), while maintaining excellent beam steering capability and aperture efficiency.

[0044] The specific parameters of the customized horn in the present invention are: a = 180mm, b = 140mm, e = 42mm, l = 120mm. The passive metalens placed inside the horn is a hybrid multilayer gradient refractive index metalens, that is, metalens units with different equivalent refractive indices are arranged in a regular pattern to form a metalens. When the wave emitted from the excitation source passes through different parts of the lens, the electromagnetic wave will experience different spatial delays, thereby generating a phase difference, thereby changing the field distribution on the aperture surface of the feed horn. Assuming that the center of the lens aperture is the maximum refractive index n0, the refractive index of each unit on the lens aperture satisfies the formula:

[0045]

[0046] Where r is the distance between the unit and the center point of the array, F is the focal length, and t is the total thickness of the lens. The above is the design of the core layer of the super lens. Taking into account the reflection caused by impedance mismatch between the medium and the air in the propagation path of electromagnetic waves, impedance matching is required between the interfaces. Therefore, two additional impedance matching layers composed of super lenses need to be added, namely the first matching layer and the second matching layer, which are inserted between the air and the super lens core layer. The specific principle structure is shown in Figure 2(a). The super lens has a total of 14 dielectric plates, and there is an air layer between the dielectric plates. From the inside of the speaker to the outside, there are 3 first matching layers, 7 core layers, and 4 second matching layers, with thicknesses of t respectively. m1 , t c , t m2 The specific structure of the super lens unit is shown in Figure 2(b). The subwavelength square metal ring 22 is etched on the dielectric substrate 21. The dielectric substrate is F4B, and its relative dielectric constant ε r = 2.65, the loss tangent is 0.0015, and the thickness is 0.5mm, so the loss is very low. As shown in 2(c), the side length of the metal square is L s , the width of the square ring is w, the period of the unit is p, and the spacing between the dielectric plates is 2.5 mm. As shown in Figure 2(d), the equivalent refractive index of the lens unit changes with L s The simulation results show that the imaginary part of the refractive index is almost zero and does not change with L. s changes, while the real part changes with L s Gradually increases from 1.1 to 2.2. After simulation optimization, the structural parameters are: t m1 =9mm, t m2 =12mm, t c =21mm, w=0.2mm, p=3mm. Figure 3(a) shows the refractive index distribution on the core layer and the matching layer obtained by theoretical calculation. Figure 3(c) shows the electric field distribution of the feed horn after loading the actual super lens unit array on the xoz plane (left picture) and the yoz plane (right picture). It can be seen that an obvious plane wavefront has been formed on the horn mouth surface. The near-field field distribution of the feed horn loaded with the super lens was measured in the near-field scanning system. During the test, a rectangular waveguide probe was used to scan on a plane 10mm away from the horn aperture. The electric field distribution result of the test is shown in Figure 3(d). The dotted box is the placement area of ​​the transmission array. The amplitude diagram on the left shows that the energy in the area is relatively concentrated and uniform, and the phase diagram on the right shows that it is basically in phase within the area, which meets the requirements of the present invention for the near-field electromagnetic wavefront state.

[0047] The small-scale electrically adjustable transmission array of the present invention is composed of 3×5 units. The schematic diagram of the transmission unit is as follows: Figure 1As shown, when viewed from the horn mouth, the transmission unit includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, and a third metal layer, which are stacked in sequence. The structural schematics of the electrically adjustable transmission unit 33 are shown in Figures 4(a) and 4(b). The first metal layer includes a receiving unit 4 and a phase shifter 5, the second metal layer is a metal ground, and the third metal layer is a radiation unit 6. The receiving unit 4 is composed of three rectangular metal patches. The middle patch is a parasitic patch 41. The rectangular patches 42 on both sides are connected by a metal wire 43. The midpoint of the metal wire is connected to the input end of the phase shifter 5. The receiving unit receives the electromagnetic wave from the horn and feeds it into the phase shifter. The phase shifter is constructed by cascading two RTPSs 51. Each RTPS consists of a four-port directional coupler 54, two short-circuited microstrip lines 52, and two varactor diodes 53 (MACOM MA46H120) located therebetween. The cathodes of the two varactor diodes are connected to the coupled port and the through port of the coupler, respectively, while the anodes are connected to the short-circuited microstrip lines. Metal blind vias 32 connect the short-circuited microstrip lines to the second metal layer. A metal through-hole 31 connects the output of the phase shifter to the central rectangular patch 61 of the radiating element on the third metal layer, feeding the phase-shifted signal into the radiating element. To isolate the metal through-hole from the intermediate layer, the present invention etches a circular gap with a diameter of 0.4 mm in the second metal layer. The radiating element consists of the central rectangular patch 61 and two U-shaped patches 62 on the periphery. The dielectric layer of the transmission element is made of Rogers RO4003C, which has a relative dielectric constant of 3.55 and a loss tangent of 0.0027. The dielectric thicknesses are h1 = 0.813 mm and h2 = 1.524 mm, respectively. A 15 kΩ resistor 55 is connected to the DC bias line 56. Because the DC current in the varactor diode is negligible under reverse bias conditions, these resistors are used to block the RF current. The structural parameters of each module are: a1=9mm, a2=6.5mm, a3=1mm, a4=1.9mm, a5=5.9mm, a6=20.7mm, b1=13.6mm, b2=13.8mm, b3=13.5mm, b4=13.7mm, b5=21mm, g1=0.5mm, g2=0.7mm, g3=0.35mm, g4=0.8mm, l1=2mm, l2=2.2mm, p t =29.7mm, w1 = 5mm, w2 = 0.8mm, w3 = 4.9mm, and w4 = 2.05mm. The simulated transmission phase and amplitude distribution of the phase shifter as the capacitance of the varactor changes are shown in Figure 4(c). The transmission phase can reach over 270° in the 5-5.9 GHz band, and the transmission amplitude is greater than -2.2dB in the 5.2-5.9 GHz band.

[0048] In this example, a custom feed horn, metalens, and electrically tunable transmission array were fabricated. A photograph of the metalens is shown in Figure 5(a). The left image shows the matching layer dielectric plate, the middle image shows the core layer dielectric plate, and the right image shows the assembled metalens. The metalens is assembled and secured with several nylon nuts and bolts and loaded onto the extension of the feed horn. A photograph of the electrically tunable transmission array is shown in Figure 5(b).

[0049] First, the transmission amplitude and phase of the electrically adjustable transmission array were tested in a focusing lens antenna test system. The test results are shown in Figure 5(c). All varactor diodes in the array are controlled by the same DC bias voltage. In the range of 5.4 GHz to 5.55 GHz, the transmission phase of the array can be varied by at least 300° by adjusting the voltage. In order to verify the beam scanning performance of the reconfigurable transmission array antenna in the present invention, a test system was built in this embodiment. The antenna system and its far-field pattern test environment are shown in Figure 5(d). The capacitance value of the varactor diode of each unit in the transmission array of the present invention can be continuously and independently tuned. Therefore, by accurately selecting the control voltage, the phase shift of each unit can be independently and flexibly adjusted to achieve precise beam steering. The radiation patterns on the E-plane, H-plane, and 45° oblique plane at 5.4 GHz, 5.45 GHz, and 5.55 GHz are shown in Figures 6(a), 6(b), and 6(c), respectively. The forward radiation gains at these frequencies are 12.7dBi, 14.9dBi, and 14.8dBi, respectively. Calculations show that the system achieves a maximum forward aperture efficiency of 29.6% at 5.45GHz. Within the 5.4GHz to 5.55GHz frequency band, the E-plane main lobe can continuously scan within an elevation angle range of -35° to 35°; on a 45° slant plane, the main lobe can continuously scan within an elevation angle range of -40° to 40°. Since there are only three rows of transmission elements on the H-plane, the degree of freedom for phase tuning on the transmission array is very limited, resulting in a main lobe scanning range from -30° to 30°. Experimental measurements were conducted on the input port reflection coefficient of the antenna system under various beam scanning conditions. Typical curves are shown in Figure 6(d), showing that the reflection coefficient is generally below -10dB within the 5.4GHz to 5.55GHz range.

[0050] In summary, this invention proposes a novel reconfigurable transmission array beam-scanning antenna. It consists of a customized rectangular feed horn, a passive metalens placed within the horn's aperture, and a small-scale transmission array. This highly compact structure demonstrates excellent performance in terms of beam scanning range and aperture efficiency. Electromagnetic waves excited by the rectangular horn, after passing through the metalens with a refractive index gradient, form plane wavefronts of equal radiation and phase very close to the horn's aperture. Therefore, placing an electrically tunable transmission array consisting of only 3×5 elements very close to the feed aperture can effectively meet beam steering requirements. The entire beam-scanning antenna system measures only 3.3λ0 × 2.6λ0 × 3.5λ0 (including the horn), making it the smallest reconfigurable transmission array beam-scanning antenna currently available. The transmission array utilizes only 60 tunable elements, a minimal number. Far-field test results show a maximum radiation gain of 14.9 dBi at 5.45 GHz, demonstrating a high aperture efficiency of 29.6%. Through precise voltage control, the antenna system achieves an elevation scanning range of ±35°, ±30°, and ±40° in the E-plane, H-plane, and 45° oblique plane, respectively, within the 5.4 GHz to 5.55 GHz frequency band, demonstrating excellent beam scanning performance. Table 1 compares the performance of existing reconfigurable transmission array beam scanning antennas. It can be seen that the present invention has the smallest footprint, uses the fewest transmission array elements and control components, and exhibits high maximum aperture efficiency and beam scanning capability.

[0051] It should be understood that the operating frequency range of the present invention depends on the unit structural parameters and is only used to illustrate the present invention and is not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the structural parameters of the present invention by those skilled in the art fall within the scope defined by the claims attached to this application.

Claims

1. A compact reconfigurable transmission array beam scanning antenna, characterized by: The invention comprises a rectangular feed horn (1), a passive metal lens (2) disposed inside the horn mouth of the rectangular feed horn (1), and an electrically adjustable transmission array (3) disposed on the outer surface of the passive metal lens (2); wherein the front portion of the rectangular feed horn (1) is a hollow large rectangle, the rear portion is a hollow small rectangle, and the four corresponding faces of the large rectangle and the small rectangle are connected by trapezoidal plates to form a horn-shaped hollow body; the passive metal lens (2) is composed of 14 printed circuit boards and air layers alternately stacked; the electrically adjustable transmission array (3) is composed of a plurality of transmission units arranged in a matrix; The passive superlens (2) is composed of 14 printed circuit boards and air layers stacked alternately, each printed circuit board is composed of 46×60 superlens units (26), and each unit contains a medium (21) of the superlens unit and a square metal ring (22); when viewed from the inside of the speaker to the outside, the 14 printed circuit boards are divided into three layers, namely a first matching layer (23), a core layer (24), and a second matching layer (25); the first matching layer (23) contains 3 printed circuit boards, the core layer (24) contains 7 printed circuit boards, and the second matching layer (25) contains 4 printed circuit boards; the metal of each printed circuit board faces outward, the metal patterns on the 7 printed circuit boards in the first matching layer and the second matching layer are the same, and the metal patterns on the 7 printed circuit boards in the core layer are the same; The electrically adjustable transmission array (3) is composed of a plurality of electrically adjustable transmission units (33) arranged in a matrix. The electrically adjustable transmission array (3) is placed 10 mm outside the horn mouth of the rectangular feed horn (1) and is composed of 3×5 electrically adjustable transmission units (33). The electrically adjustable transmission units (33) are integrated with 4 variable capacitance diodes (53), and a total of 60 variable capacitance diodes are used. The plane area of ​​the electrically adjustable transmission array (3) is smaller than the plane area of ​​the horn aperture.

2. A compact reconfigurable transmission array beam scanning antenna as claimed in claim 1, characterized in that The rectangular feed horn (1) has its structural dimensions adjusted based on a standard horn antenna, and its aperture is extended along its normal direction, and the passive super lens (2) is placed in the extended portion to improve the electromagnetic field distribution on the aperture surface.

3. The compact reconfigurable transmission array beam scanning antenna according to claim 1, characterized in that: The thickness of the air layer between the printed circuit boards of the passive super lens (2) is fixed, and the equivalent refractive index of the super lens unit (26) depends on the outer square side length Ls of the square metal ring (22), and the value range of Ls is: greater than the width w of the square metal ring (22) and less than the width p of the medium (21) of the super lens unit.

4. The compact reconfigurable transmission array beam scanning antenna according to claim 1, characterized in that: The electrically adjustable transmission array (3) is arranged from the inside to the outside of the horn mouth, and each electrically adjustable transmission unit (33) includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, and a third metal layer stacked in sequence; wherein the first metal layer includes a receiving unit (4) and a phase shifter (5); the receiving unit (4) is composed of three rectangular metal patches arranged side by side, with a parasitic patch (41) in the middle and rectangular patches (42) on both sides, and the two rectangular patches (42) are connected by a metal thin wire (43); the midpoint of the metal thin wire is connected to the input end of the phase shifter (5); the receiving unit receives the electromagnetic wave from the rectangular feed horn (1) and feeds it into the phase shifter (5).

5. The compact reconfigurable transmission array beam scanning antenna according to claim 4, characterized in that: The phase shifter (5) is two cascaded orthogonal bridge reflection type phase shifters (51), each of which is composed of a four-port directional coupler (54), two short-circuit microstrip lines (52) and two varactor diodes (53), wherein the cathode of the varactor diode (53) is respectively connected to the coupling port and the through port of the four-port directional coupler (54), and the anode is connected to the short-circuit microstrip line (52); the other ends of the two short-circuit microstrip lines (52) are each connected to the second metal layer by a metal blind hole (32).

6. The compact reconfigurable transmission array beam scanning antenna according to claim 4, characterized in that: The third metal layer is a radiation unit (6), which is composed of a central rectangular patch (61) and two peripheral U-shaped patches (62); the metal through hole (31) connects the output end of the first metal layer phase shifter (5) and the central rectangular patch (61) of the third metal layer, and is used to feed the phase-shifted signal into the radiation unit; the second metal layer is a fully covered metal, and there is a circular hole on the second metal layer passing through the metal through hole (31) with a diameter larger than the aperture of the metal through hole (31), and the metal through hole (31) does not contact the second metal layer.

7. The compact reconfigurable transmission array beam scanning antenna according to claim 1, characterized in that: The electrically adjustable transmission array (3) comprises a phase shifter (5) on each transmission unit including two orthogonal bridge-connected reflective phase shifters (51), and each orthogonal bridge-connected reflective phase shifter (51) includes two varactor diodes (53); a DC bias line (56) is drawn from the short-circuited microstrip line (52) of the phase shifter (5) and connected to a DC voltage controller via a 15 kilo-ohm resistor (55).

8. The compact reconfigurable transmission array beam scanning antenna according to claim 7, characterized in that: The four varactor diodes (53) on each transmission unit are connected in parallel and controlled by the same reverse bias voltage. The phase of the electromagnetic wave passing through the 15 units on the electrically adjustable transmission array (3) is controlled by 15 independent voltages. The phase shift values ​​of the 15 units on the adjustable transmission array (3) are precisely controlled by DC voltage to achieve beam scanning in a maximum elevation angle range of ±40° in 8 azimuth directions with azimuth angles equal to 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°.

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