Ultra-inclination low-profile end-fire antenna and radar detection system based on multi-mode amplitude and phase control

Abstract

The application discloses a super-large inclination angle low-profile end-fire antenna and radar detection system based on multi-mode amplitude-phase control, which comprises a main radiation patch, the main radiation patch comprises a rectangular patch, two upper rectangular branches and two lower rectangular branches with different lengths are vertically connected to both ends of the rectangular patch along the positive direction of the y-axis, the rectangular branches respectively extend away from the corresponding rectangular patch and are electrically connected with the rectangular patch, two annular slot grooves are formed in the rectangular patch, the widths and inner diameters of the two annular slot grooves are different, a coaxial feeder is arranged on the annular slot groove, the rectangular patch is arranged on the upper surface of a dielectric layer, a metal ground plate is arranged on the lower surface of the dielectric layer, and a circular hole corresponding to the annular slot groove is formed in the metal ground plate. The antenna and the system have the characteristics of super-large beam inclination angle, low profile, single-layer structure, easy processing, high gain and high directivity.

Description

Technical Field

[0001] This invention belongs to the field of antenna engineering technology, specifically relating to an ultra-large tilt angle low profile end-fire antenna and radar detection system based on multi-mode amplitude phase modulation. Background Technology

[0002] With the rapid development of wireless systems such as low-Earth orbit satellite communication, 5G / 6G base stations, and radar detection, the demand for antennas with high gain and large-angle tilted beam radiation characteristics is increasing. In scenarios such as satellite communication and terrestrial base stations, tilting the main lobe of the antenna beam in a specific direction can effectively reduce path loss, increase channel capacity, and enhance anti-interference capabilities. At the same time, modern wireless systems are evolving towards miniaturization, high capacity, and integration, creating an urgent need for wideband, high-gain antenna solutions with customizable beam tilt angles within a compact size.

[0003] In existing research on tilted-beam microstrip antennas, CN115275643A discloses a microstrip antenna with customizable beam tilt angle and its design method. This discloses a microstrip antenna based on an "I"-shaped subwavelength excitation patch, which calculates the phase difference between adjacent patches using a formula derived from the generalized Snell's law, thereby achieving customizable beam tilt angle design. This antenna has a single-layer structure, offering advantages such as simple structure and low profile. However, the subwavelength excitation patch in this scheme uses a parasitic array control method, and its beam tilt angle depends on the gradual change of the patch's equivalent refractive index. The achievable beam tilt angle range is limited by the range of equivalent refractive index variation of the patch unit—the equivalent refractive index range of the "I"-shaped patch in this scheme is 1.07 to 1.68. This limited refractive index adjustment range restricts further expansion of the beam tilt angle. Simulation results show that the antenna achieves two beam tilt angles of 30° and 50° at the 5.8 GHz frequency, with maximum gains of 8.42 dBi and 10.87 dBi, respectively, but has not yet broken through the 50° tilt angle limit.

[0004] In summary, existing tilted beam microstrip antenna technology faces the following challenges: First, schemes based on parasitic array refractive index modulation are limited by the range of variation of the equivalent refractive index of the patch unit, making it difficult to break through 50° in beam tilt angle, which cannot meet the urgent need for ultra-large tilt angles in some scenarios; Second, traditional single-mode microstrip antennas often face the problem of significant gain reduction when achieving large-angle beam tilt; Third, some wide-angle scanning schemes rely on multilayer dielectric substrates or active switching devices, resulting in complex structures and high costs. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention aims to provide an ultra-large tilt angle low profile end-fire antenna and radar detection system based on multi-mode amplitude phase modulation. The antenna and system have ultra-large beam tilt angle (which can break through the 50° limit), low profile, single-layer structure, easy processing, and high gain and high directivity.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation includes a radiating patch, wherein the radiating patch includes a first reflective patch, a second reflective patch, a main radiating patch and a directional patch arranged sequentially at intervals along the positive x-axis and of different sizes. The main radiating patch includes a rectangular patch, with two upper rectangular branches and a lower rectangular branch of different lengths perpendicularly connected to both ends of the rectangular patch along the y-axis. The rectangular branches extend away from the corresponding rectangular patch and are electrically connected to the rectangular patch. The rectangular patch has two annular slots, and the width and inner diameter of the two annular slots are different. A coaxial feeder is installed on the annular slot; A rectangular patch is disposed on the upper surface of the dielectric layer; a metal floor is disposed on the lower surface of the dielectric layer, and circular holes corresponding to the annular slots are formed on the metal floor.

[0007] The annular slot is divided into a first annular slot and a second annular slot. A first coaxial feeder is provided on the first annular slot, and a second coaxial feeder is provided on the second annular slot. The circular hole is divided into a first circular hole and a second circular hole. The first circular hole and the first coaxial feeder coincide, and the second circular hole and the second coaxial feeder coincide. The first and second circular holes are used to prevent the coaxial feeder probe from short-circuiting with the metal ground.

[0008] The metal floor has a first circular hole and a second circular hole to prevent short circuits between the inner and outer conductors of the first and second coaxial feeders. The center of the circular hole coincides with the coaxial feeder. The outer conductors of the two coaxial feeders are electrically connected to the metal floor.

[0009] The inner conductor of the first coaxial feed is located at the center of the rectangular patch and is used to excite the TM04 mode of the microstrip antenna; the first annular slot is opened on the rectangular patch and surrounds the inner conductor of the first coaxial feed and is used to adjust the impedance matching of the port. The inner conductor of the second coaxial feeder is offset from the inner conductor of the first coaxial feeder in both the x and y directions, and is used to excite the TM12 mode of the microstrip antenna; the second annular slot surrounds the inner conductor of the second coaxial feeder and is used to adjust the impedance matching of the port.

[0010] The dielectric layer has dielectric through holes of the same diameter corresponding to the positions of the inner conductors of the first and second coaxial feeders, which facilitates the passage of the feed post. The inner conductors of the first and second coaxial feeders are inserted into the corresponding dielectric through holes and penetrate the dielectric layer. The top of the inner conductor is flush with the rectangular patch and electrically connected.

[0011] Both the first and second coaxial feeders are constructed using SMA connectors. The top ends of the inner conductors of both the first and second coaxial feeders are electrically connected to rectangular patch panels, and their outer conductors are electrically connected to a metal ground plane.

[0012] The upper and lower rectangular stubs are connected to the two ends of the rectangular patch, respectively, located at the zero point of the electric field of the TM12 mode and at the strong point of the electric field of the TM04 mode. By adjusting the size of the stubs, the resonant frequency of the TM04 mode can be reduced, so that the resonant points of the TM12 mode and the TM04 mode coincide in the working frequency band.

[0013] Each patch is a rectangular metal patch, and each patch has two rectangular branches of different lengths perpendicularly connected to both ends of its rectangular body along the positive y-axis. The rectangular branches extend away from the corresponding patch body and are electrically connected to the patch body. The first and second reflective patches are located on the negative x-axis side of the main radiating patch, and the guiding patch is located on the positive x-axis side of the main radiating patch. There is no direct electrical connection between the patches; they are parasiticly excited by each other through spatial electromagnetic coupling. The rectangular body of the main radiating patch has two annular slots with different widths and inner diameters. All radiation patches are disposed on the upper surface of the second dielectric layer.

[0014] The first reflective patch, the second reflective patch, and the directional patch are all parasitic patches, which are used as directional devices or reflectors, respectively, to further improve the beam tilt angle.

[0015] By adjusting the lengths of the upper and lower rectangular stubs on the patch, the resonant frequencies of the antenna's TM12 and TM04 modes can be made to coincide within the operating frequency band.

[0016] Impedance matching is achieved by independently adjusting the input impedance of the two coaxial feeders by changing the width and inner diameter of the two annular slots respectively.

[0017] The two coaxial feeders are used to excite the TM12 and TM04 modes of the antenna, respectively, and the feed points of the two coaxial feeders are located at the electric field zero point of the other mode on the second patch to achieve high port isolation.

[0018] By changing the amplitude and phase of the feed signals from the two coaxial feeders, it is possible to eliminate one beam and enhance the other in the dual beams generated by the TM04 mode, thereby forming a single beam with a large angle tilt.

[0019] When the phase difference between the two feed ports is set to 90°, the TM04 mode is used in the H plane. θ The phase in the <0° region is 180°. θ The phase of the >0° region is 0°, and the characteristic of the TM12 mode maintaining a 90° phase in space makes the far-field electric field superimposed in phase in the θ>0° direction. θ <0° direction antiphase cancellation, producing to θ A beam tilted at >0°; by further adjusting the two-port feed amplitude ratio, the pointing angle and gain of the tilted beam can be controlled.

[0020] By increasing the thickness of the dielectric layer, the gain of the TM12 and TM04 modes along the antenna beam tilt direction is improved; when the thickness satisfies 0.08λ>h1>0.07λ, the gain can be effectively improved (λ is the wavelength of the operating frequency 6.55GHz in free space).

[0021] The first patch, the third patch, and the fourth patch are obtained by proportionally enlarging or reducing the second patch, and the spacing between them satisfies a preset relationship to further improve the beam tilt angle.

[0022] This is an ultra-large tilt angle, low profile end-fire antenna based on multi-mode amplitude phase modulation. The antenna operates in the 6.52-6.58 GHz band, with a two-port reflection coefficient less than -10 dB and a maximum pattern gain of 10.3 dB. θ =66° direction.

[0023] The end-fire antenna serves as the transceiver antenna of the radar detection system, effectively detecting low-altitude or ultra-low-altitude targets. It is particularly suitable for applications requiring large-angle detection, such as UAV detection, perimeter security, and highway target monitoring.

[0024] The beneficial effects of this invention are: The antenna element excites the TM12 and TM04 modes of the microstrip antenna through two coaxial feeders, respectively. Each of the two coaxial feeders is located at the zero point of the electric field of the other mode, which has high isolation within the operating frequency band and realizes independent amplitude and phase control of the two modes.

[0025] Increasing the thickness of the dielectric layer (i.e., increasing the profile height) can significantly improve the gain of the TM12 and TM04 modes in the beam tilt direction. The mechanism is that the increased profile height significantly enhances the equivalent magnetic current amplitude radiated in the H-plane relative to the reverse magnetic current, thereby enabling the TM12 mode to transform from its original H-plane non-radiating state to wide-beam radiation, and the TM04 mode to transform from its original H-plane non-radiating state to dual-beam radiation. This mechanism effectively expands the antenna's beam coverage and improves the radiation performance in the specified direction.

[0026] Exciting the TM12 mode alone can generate a wide normal beam, while exciting the TM04 mode can generate a dual beam. By changing the input amplitude and phase of the two feed ports, one beam of the dual beam can be suppressed while the other beam is enhanced, thereby achieving a large-angle tilt of the beam.

[0027] Based on the principle of electric field superposition, the TM04 mode exhibits phase reversal characteristics on the H-plane. θ When <0° is 180°, θ When >0° is 0°), the TM12 mode maintains a 90° phase in space. When a 90° feed phase difference is introduced between the TM04 mode and the TM12 mode, in θ The electric fields in the far region of <0° cancel each other out in opposite phase. θ The electric fields in the far-field region above 0° are superimposed in phase, thus forming a directional electric field. θ A single beam tilted at >0°; by adjusting the amplitude ratio of the two-port feed, the pointing angle and gain of the tilted beam can be further controlled.

[0028] By adjusting the width and inner diameter of the two annular slots respectively, the input impedance of the two power supply ports can be flexibly adjusted, making it easy to achieve good matching.

[0029] By setting parasitic patches of enlarged and reduced size on both sides of the main radiating patch as directors and reflectors, the tilt angle of the beam can be further improved.

[0030] This invention's technical solution is based on the multi-mode theory of microstrip antennas. Through mode selection excitation and amplitude-phase modulation, it applies multi-mode theory to design an ultra-large tilt angle low-profile end-fire antenna and radar detection system based on multi-mode amplitude-phase modulation. In terms of radiation performance, the antenna pattern achieves a maximum gain of 10.3 dB, appearing at... θ =66°. Within the 6.52-6.58GHz operating frequency band, the reflection coefficient at both ports is less than -10dB, and the antenna element possesses the advantages of a large beam tilt angle and high gain. In terms of antenna structure, this antenna element has a simple structure, requiring no active components and using only a single dielectric substrate, all of which reduce the manufacturing cost of the antenna element. Furthermore, its low profile and miniaturization are outstanding, with dimensions of only 1.88×1.1×0.076λ.3 It is a miniaturized antenna element with ultra-low profile, multi-mode fusion, and ultra-large beam tilt angle.

[0031] In summary, this invention designs an ultra-large tilt angle low profile end-fire antenna and radar detection system based on multi-mode amplitude phase modulation, which can well meet the communication requirements with extremely high gain and directivity requirements. Attached Figure Description

[0032] Figure 1 This is a top view of the single-patch multi-mode phase-controlled ultra-large tilt angle low-profile end-fire antenna of the present invention.

[0033] Figure 2 This is a front view of the single-patch multi-mode amplitude phase-controlled ultra-large tilt angle low-profile end-fire antenna of the present invention.

[0034] Figure 3 This is a bottom view of the single-patch multi-mode phase-controlled ultra-large tilt angle low-profile end-fire antenna of the present invention.

[0035] Figure 4 This is a top view of the ultra-large tilt angle low profile end-fire antenna with parasitic patch for multi-mode amplitude phase modulation according to the present invention.

[0036] Figure 5 A front view of the ultra-large tilt angle low profile end-fire antenna with parasitic patch of the present invention.

[0037] Figure 6 A bottom view of the ultra-large tilt angle low profile end-fire antenna with parasitic patch of the present invention.

[0038] Figure 7 The figure shows the simulation results of the port reflection coefficient of the ultra-large tilt angle low profile end-fire antenna with parasitic patch of the present invention.

[0039] Figure 8 The simulation results of port S12 for a multi-mode amplitude phase-controlled ultra-large tilt low-profile end-fire antenna with parasitic patch are shown.

[0040] Figure 9 The radiation pattern of the single-patch multi-mode phase-controlled ultra-large tilt angle low profile end-fire antenna of the present invention is shown when the two-port feed amplitude ratio is 0.7:1 and the phase difference is 90°.

[0041] Figure 10 The radiation pattern of the ultra-large tilt angle low profile end-fire antenna with parasitic patch of the present invention is shown when the two-port feed amplitude ratio is 0.7:1 and the phase difference is 90°. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings.

[0043] Example 1: Please see Figures 1 to 3 A single-patch, multi-mode, phase-controlled, ultra-large tilt angle, low-profile end-fire antenna includes a rectangular patch 141, an upper rectangular stub 142, a lower rectangular stub 143, a dielectric layer 144, a first coaxial feed 145, a second coaxial feed 147, a first annular slot 146, a second annular slot 148, a metal ground plane 149, and a first circular hole 1410 and a second circular hole 1411 formed on the metal ground plane 149. A dielectric via is formed on the dielectric layer 144 for the coaxial feed to pass through.

[0044] Specifically, the inner conductor of the first coaxial feed 145 is located slightly below the center of the rectangular patch 141 and is used to excite the TM04 mode of the microstrip antenna; the first annular slot 146 is formed on the rectangular patch 141, surrounding the inner conductor of the first coaxial feed 145, and is used to adjust the impedance matching of this port. The inner conductor of the second coaxial feed 147 is located slightly below the right of the rectangular patch 141 and is used to excite the TM12 mode of the microstrip antenna; the second annular slot 148 surrounds the inner conductor of the second coaxial feed 147 and is used to adjust the impedance matching of this port.

[0045] Dielectric through-holes of the same diameter are respectively opened on the dielectric layer 144 at the positions of the inner conductors of the first coaxial feeder 145 and the second coaxial feeder 147 to facilitate the passage of the feed post. The inner conductors of the first coaxial feeder 145 and the second coaxial feeder 147 are respectively inserted into the corresponding dielectric through-holes and penetrate the dielectric layer 144. The top of the inner conductor is flush with and electrically connected to the rectangular patch 141.

[0046] Both the first coaxial feeder 145 and the second coaxial feeder 147 are constructed using SMA connectors. The top ends of the inner conductors of the first coaxial feeder 145 and the second coaxial feeder 147 are electrically connected to the rectangular patch 141, and their outer conductors are electrically connected to the metal ground plane 149.

[0047] The upper rectangular stub 142 and the lower rectangular stub 143 are connected to the two ends of the rectangular patch 141 respectively. They are located at the zero point of the electric field of the TM12 mode and at the strong point of the electric field of the TM04 mode. By adjusting the size of the stub, the resonant frequency of the TM04 mode can be reduced, so that the resonant points of the TM12 mode and the TM04 mode coincide in the working frequency band.

[0048] The metal floor 149 has a first circular hole 1410 and a second circular hole 1411 to prevent short circuits between the inner and outer conductors of the first coaxial feeder 145 and the second coaxial feeder 147. The center of the circular hole 1410 coincides with the center of the coaxial feeder 145, and the center of the circular hole 1411 coincides with the center of the coaxial feeder 147. The outer conductors of the two coaxial feeders are electrically connected to the metal floor 149 respectively.

[0049] Example 2: Please see Figure 4-6 This embodiment, based on Embodiment 1 above, provides an ultra-large tilt angle low-profile end-fire antenna with multi-mode amplitude phase modulation and parasitic patches. The antenna includes a first reflector patch 12, a second reflector patch 13, a main radiating patch 14, and a guiding patch 15. The rectangular patch 141 is completely identical to the single-patch multi-mode amplitude phase modulation microstrip antenna structure with ultra-large beam tilt angle described in Embodiment 1. The area of ​​the dielectric layer 16 is correspondingly increased to support each parasitic patch.

[0050] The first reflective patch 12 and the second reflective patch 13 have no annular gaps or feeders, only rectangular patches and rectangular branch structures. Similarly, the guide patch 15 has no annular gaps or feeders, only rectangular patches and rectangular branch structures. The first reflective patch 12 is obtained by scaling the main radiating patch kx1 times in the length direction and ky1 times in the width direction; the second reflective patch 13 is obtained by scaling the main radiating patch kx2 times in the length direction and ky2 times in the width direction; the guide patch 15 is obtained by scaling the main radiating patch kx3 times in the length direction and ky3 times in the width direction. The first reflective patch 12 and the second reflective patch 13 are both located on the rearward radiation side of the main radiating patch 14, serving together as reflectors to reflect the electromagnetic waves radiated rearward from the main radiating patch 14 to the forward direction, thereby enhancing forward radiation gain and suppressing rearward radiation. The guiding patch 15 is located on the forward radiation side of the main radiating patch 14, serving as a director to further converge the forward radiation beam, thereby improving the antenna's directivity and gain. The first reflective patch 12 is positioned close to the main radiating patch 14 as the main reflector, while the second reflective patch 13 is positioned on the side of the first reflective patch 12 away from the main radiating patch 14 as an auxiliary reflector. Together, they achieve stepwise suppression of rearward radiation reflection.

[0051] Example 3 Based on the above embodiments, the dimensional parameters of each part of the antenna are further defined.

[0052] The rectangular patch 141 has a length of Px and a width of Py; the dielectric layer 144 has a length of Ax and a width of Ay, and is made of F4BM material with a dielectric constant of 3.5; the upper rectangular branch 142 has a length of L1 and a width of W1; and the lower rectangular branch 143 has a length of L2 and a width of W2.

[0053] The inner conductor center of the first coaxial feed 145 is offset downwards by a distance d1 relative to the center of the rectangular patch; the inner conductor center of the second coaxial feed 147 is offset downwards by a distance d2 and to the right by a distance d3 relative to the center of the rectangular patch. The inner diameter of the first annular slot 146 is r1, and the slot width is g1; the inner diameter of the second annular slot 148 is r2, and the slot width is g2. The inner conductor diameter of the first coaxial feed 145 is Da, and the inner conductor diameter of the second coaxial feed 147 is Db. The thickness of both dielectric layer 144 and dielectric layer 16 is h1.

[0054] The main radiating patch consists of the aforementioned rectangular patch 141, upper rectangular branch 142, lower rectangular branch 143, first coaxial feeder 145, second coaxial feeder 147, first annular gap 146, and second annular gap 148.

[0055] The first reflective patch 12 is obtained by scaling the main radiating patch to kx1 times in the length direction and ky1 times in the width direction; the second reflective patch 13 is obtained by scaling the main radiating patch to kx2 times in the length direction and ky2 times in the width direction; the guiding patch 15 is obtained by scaling the main radiating patch to kx3 times in the length direction and ky3 times in the width direction.

[0056] The center of the first reflective patch 12 is offset to the left by a distance dx1 relative to the center of the main radiating patch; the center of the second reflective patch 13 is offset to the left by a distance dx2 relative to the center of the main radiating patch; and the center of the guiding patch 15 is offset to the right by a distance dx3 relative to the center of the main radiating patch 14.

[0057] Among them, 0.30λ≤Px≤0.32λ, 0.78λ≤Py≤0.79λ, 2λ≤Ax≤2.4λ, 2.1λ≤Ay≤2.3λ, 0.134λ≤W1≤0.136λ, 0.0915λ≤W2≤0.979λ, 0.1090λ≤L1≤0.1094λ, 0.1090λ≤L2≤0.1094λ,0.39λ≤dl≤0.396λ,0.36λ≤d2≤0.37λ,0.075λ≤d3≤0.078λ,0.025λ≤r1≤0.0252λ,0 .0207λ≤r2≤0.0208λ,0.0109λ≤g1≤0.01094λ,0.00327λ≤g2≤0.00328λ,0.0283λ≤Da≤0.0285λ,0.0283λ≤ Db≤0.0285λ, 0.763λ≤h1≤0.765λ, 0.95≤kx1≤0.97, 1.076≤ky1≤1.080, 0.88≤kx2≤0.885, 1.03≤ky2≤1.04, 0.91≤kx3≤0.915, 0.91≤ky3≤0.915, 0.8225λ≤dx1≤0.823λ, 0.4492λ≤dx2≤0.4496λ, 0.78λ≤dx3≤0.784λ. (λ is the wavelength of the operating frequency 6.55GHz in free space.) In a preferred embodiment, the ultra-large tilt angle low-profile end-fire antenna based on multi-mode amplitude phase modulation consists of a main radiating patch and three proportionally enlarged or reduced parasitic patches arranged at a certain interval. The overall antenna dimensions are designed to be 140mm long, 100mm wide, and 3.5mm high.

[0058] To further illustrate the beneficial effects of the present invention, electromagnetic simulation software was used to simulate the port reflection coefficient, port isolation, and radiation pattern of the antenna in the above embodiments. The simulation results are as follows: Figures 7 to 10 As shown.

[0059] Figure 7 The figure shows the simulation results of the port reflection coefficient of the ultra-large tilt angle low profile end-fire antenna with parasitic patch of the present invention. In the 6.52-6.58 GHz frequency band, the reflection coefficients of both ports are less than -10 dB.

[0060] Figure 8 The figure shows the simulation results of the port isolation of the ultra-large tilt angle low profile end-fire antenna with parasitic patch of the present invention. The port isolation is less than -15dB in the operating frequency band.

[0061] Figure 9The radiation pattern of the single-patch multi-mode phase-controlled ultra-large tilt angle low-profile end-fire antenna of the present invention is shown when the two-port feed amplitude ratio is 0.7:1 and the phase difference is 90°. Its maximum radiation direction is located at θ =54°.

[0062] Figure 10 The radiation pattern of the ultra-large tilt angle low-profile end-fire antenna with parasitic patch of the present invention is shown when the amplitude ratio of the two-port feed is 0.7:1 and the phase difference is 90°. Its maximum radiation direction is located at θ =66°.

[0063] This invention is based on the multimode theory of microstrip antennas. It uses two coaxial feeders to excite the TM12 and TM04 modes respectively, and leverages the phase difference between the two modes on the H-plane—the TM04 mode at… θ The phase in the <0° region is 180°, in θ The phase in the >0° region is 0°, while the TM12 mode maintains a 90° phase in space. When a 90° feed phase difference is introduced between the two feed ports, electric field cancellation on one side and superposition on the other side can be achieved in the far-field region, thus forming a single beam with a large tilt angle. By further adjusting the feed amplitude ratio between the two ports, the pointing angle and gain of the tilted beam can be flexibly controlled. Simulation results show that the antenna has a two-port reflection coefficient of less than -10dB in the 6.52-6.58GHz band, a maximum gain of 10.3dB, and a beam pointing angle of 66°. Furthermore, by setting proportionally enlarged or reduced parasitic patches on both sides of the main radiating patch as directors and reflectors, the beam tilt angle can be further increased to 66°. This scheme does not rely on the refractive index gradient control of the parasitic array, fundamentally breaking through the 50° tilt angle limitation of the traditional scheme, and realizing a truly ultra-large beam tilt angle. At the same time, it maintains the advantages of single-layer, low profile, simple structure and easy processing, and can well meet the communication requirements with extremely high requirements for gain and directivity.

Claims

1. A low-profile end-fire antenna with ultra-large tilt angle based on multi-mode amplitude phase modulation, characterized in that, It includes a radiating patch (100), which includes a first reflective patch (12), a second reflective patch (13), a main radiating patch (14), and a guiding patch (15) arranged sequentially at intervals along the positive x-axis and having different sizes. The main radiating patch (14) includes a rectangular patch (141), and the two ends of the rectangular patch (141) along the y-axis are respectively vertically connected to two upper rectangular branches (142) and lower rectangular branches (143) of different lengths. The rectangular patch (141) has two annular slots, and the width and inner diameter of the two annular slots are different; a coaxial feeder is provided on the annular slot; A rectangular patch (141) is disposed on the upper surface of the dielectric layer (144); a metal floor (149) is disposed on the lower surface of the dielectric layer (144), and a circular hole corresponding to the annular slot is provided on the metal floor (149).

2. The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 1, characterized in that, The two annular slots are a first annular slot (146) and a second annular slot (148). A first coaxial feeder (145) is provided on the first annular slot (146), and a second coaxial feeder (147) is provided on the second annular slot (148). The circular holes are a first circular hole (1410) and a second circular hole (1411). The first circular hole (1410) and the first coaxial feeder (145) coincide, and the second circular hole (1411) and the second coaxial feeder (147) coincide. The first circular hole (1410) and the second circular hole (1411) are used to prevent the coaxial feeder probe from short-circuiting with the metal ground (149).

3. The ultra-large tilt angle low-profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 2, characterized in that, The inner conductor of the first coaxial feed (145) is located at the center of the rectangular patch (141) and is used to excite the TM04 mode of the microstrip antenna; the first annular slot (146) is opened on the rectangular patch (141) and surrounds the inner conductor of the first coaxial feed (145) for adjusting the impedance matching of the port. The inner conductor of the second coaxial feed (147) is offset from the inner conductor of the first coaxial feed (145) in both the x and y directions, and is used to excite the TM12 mode of the microstrip antenna. The second annular gap (148) surrounds the inner conductor of the second coaxial feeder (147) for adjusting the impedance matching of the port.

4. The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 3, characterized in that, The dielectric layer (144) has dielectric through holes of the same diameter corresponding to the positions of the inner conductors of the first coaxial feeder (145) and the second coaxial feeder (147) to facilitate the passage of the feed post; the inner conductors of the first coaxial feeder (145) and the second coaxial feeder (7) are respectively inserted into the corresponding dielectric through holes and penetrate the dielectric layer (144), and the top of the inner conductor is flush with the rectangular patch (141) and electrically connected.

5. The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 4, characterized in that, The first coaxial feeder (145) and the second coaxial feeder (147) are both constructed using SMA connectors. The top of the inner conductor of the first coaxial feeder (145) and the second coaxial feeder (147) are electrically connected to the rectangular patch (141) respectively, and their outer conductors are electrically connected to the metal ground plane (149). The upper rectangular stub (142) and the lower rectangular stub (143) are connected to the two ends of the rectangular patch (141), respectively. They are located at the zero point of the electric field of the TM12 mode and at the strong point of the electric field of the TM04 mode. By adjusting the size of the stub, the resonant frequency of the TM04 mode can be reduced, so that the resonant points of the TM12 mode and the TM04 mode coincide in the working frequency band.

6. The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 5, characterized in that, Each patch is a rectangular metal patch, and each patch has two rectangular branches of different lengths perpendicularly connected to both ends of the rectangular body along the y-axis. The rectangular branches extend away from the corresponding patch body and are electrically connected to the patch body. The first reflective patch (12) and the second reflective patch (13) are located on the negative x-axis side of the main radiating patch (14), and the guiding patch (15) is located on the positive x-axis side of the main radiating patch (14). There is no direct electrical connection between the patches, and they achieve parasitic excitation through spatial electromagnetic coupling. All radiation patches (100) are disposed on the upper surface of the second dielectric layer (16).

7. The ultra-large tilt angle low-profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 6, characterized in that, The first reflective patch (12), the second reflective patch (13), and the director patch (15) are all parasitic patches, which are used as directors or reflectors respectively to improve the beam tilt angle.

8. The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 7, characterized in that, By adjusting the lengths of the upper rectangular stub (142) and lower rectangular stub (143) of the patch, the resonant frequencies of the antenna's TM12 mode and TM04 mode coincide within the operating frequency band. Impedance matching is achieved by independently adjusting the input impedance of the two coaxial feeders by changing the width and inner diameter of the two annular slots (146) and the annular slot (148) respectively.

9. The ultra-large tilt angle low profile end-fire antenna based on multi-mode amplitude phase modulation according to claim 8, characterized in that, The first coaxial feeder (145) and the second coaxial feeder (147) are used to excite the TM12 mode and TM04 mode of the antenna, respectively. The feed points of the first coaxial feeder (145) and the second coaxial feeder (147) on the second reflective patch (13) are located at the electric field zero point of the other mode, so as to achieve high port isolation. By changing the amplitude and phase of the feed signals of the first coaxial feeder (145) and the second coaxial feeder (147), it is possible to eliminate one beam and enhance the other beam in the dual beam generated by the TM04 mode, thereby forming a single beam with a large angle tilt.

10. The end-fire antenna according to any one of claims 1-9, characterized in that, As a transceiver antenna for radar detection systems, the end-fire antenna can effectively detect low-altitude or ultra-low-altitude targets. It is suitable for applications with strict requirements for large tilt angle detection, such as UAV detection, perimeter security, and highway target monitoring.

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