Time-modulation low-scattering strong-coupling broadband array antenna with diodes integrated on array surface

Abstract

The invention discloses a time-modulation low-scattering strong-coupling broadband array antenna with diodes integrated on an array plane, and relates to the technical field of antennas. The array antenna adopts a multilayer printed board technology, and comprises a wide-angle impedance matching layer, a dielectric substrate printed with a dipole radiation unit and an array plane integrated diode circuit, and a metal reflection floor integrated with a microstrip power divider. Strong coupling between the dipole radiation units is realized through the coupling gaps. The array surface integrated diode circuit comprises a first group of diodes and a second group of diodes. The first group of diodes is loaded at a dipole coupling gap and is used for regulating and controlling the access state of a parasitic metal structure. And the second group of diodes are loaded at the joint of the feed balun and the dipole and are used for reconstructing a feed mode. According to the invention, through time sequence regulation and control of the array plane integrated diode, on the premise of ensuring basic stability of antenna radiation characteristics, time modulation and frequency spectrum shift of a scattered field are realized by using a compact array plane integrated structure, and a radar cross section of the antenna in a 2-3GHz working frequency band is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a time-modulated, low-scattering, strongly coupled broadband array antenna with integrated diodes in the array. Background Technology

[0002] Phased array antennas, due to their flexible beam scanning and high gain, occupy a core position in modern radar, communication, and electronic warfare systems. With the increasing demands for system integration and operating bandwidth in multifunctional integrated radio frequency systems, tightly coupled dipole arrays (TCDAs) have emerged. TCDAs utilize strong capacitive coupling introduced between elements to counteract the floor inductive effect in the low-frequency band, thereby achieving broadband and wide-angle scanning performance at extremely low profiles. For example, Chinese patent application CN202110120853.9, "Ferrite-loaded dual-polarized low-profile strongly coupled ultra-wideband phased array antenna," achieves low profile and excellent radiation performance by loading ferrite materials and a special dipole arrangement. However, such strongly coupled arrays typically contain large-area metallic radiators and reflective floors, resulting in a high radar cross section (RCS) within the band, making them easily detectable by enemy radar and severely impacting the platform's stealth survivability.

[0003] To reduce the RCS of antenna arrays, existing technical solutions mainly include shape modification, loading absorbing materials, and employing passive cancellation techniques. For example, Chinese patent application CN202511411723.5, "Low RCS Broadband Array Antenna and Design Method Based on Shape Modification and Absorbing Materials," reduces scattering by modifying the Vivaldi antenna and covering it with absorbing materials. However, the introduction of absorbing materials significantly increases the antenna's weight and profile height, and the dielectric loss of the material inevitably reduces the antenna's radiation efficiency and gain, making it difficult to meet the stringent requirements of modern low-scattering platforms for lightweight and high efficiency. Another common method utilizes the principle of phase cancellation, such as Chinese patent application CN202510676979.2, "A Low-Scattering Ultra-Widebandwidth Angle-Scanning Antenna Array," which reduces RCS by arranging subarrays of different structures in a checkerboard pattern and utilizing the phase difference in reflection between the structures. However, such passive reduction methods usually have narrow bandwidth, and the fixed structure is difficult to adapt to complex and ever-changing electromagnetic threat environments. At the same time, the design of heterogeneous units often disrupts the periodicity of the array and deteriorates the active standing wave performance during large-angle scanning.

[0004] In recent years, the introduction of a time dimension into four-dimensional antenna arrays (also known as time-modulated arrays, TMAs) has provided new degrees of freedom for electromagnetic control. Existing literature (e.g., Yang, S. et al. "Complete and Unified Time- and Frequency-Domain Study on 4-D Antenna Arrays," IEEE Trans. Antennas Propag., 2020) points out that the spectral distribution of electromagnetic waves can be flexibly controlled by periodically modulating radio frequency switches. However, existing time modulation techniques are mostly used for antenna radiation pattern synthesis (such as sidelobe suppression and multi-beamforming) or for signal modulation in wireless communication. Although Chinese patent application CN202411856173.3, "Ultra-wideband amplitude-phase independent reconfigurable metasurface based on single-PIN diode control," proposes to use PIN diodes to achieve amplitude-phase control of metasurfaces, it mainly targets transmission / reflection array elements, rather than strongly coupled antenna arrays with broadband radiation capabilities.

[0005] Currently, few technologies can effectively apply time modulation techniques to the in-band scattering control of strongly coupled broadband arrays. Existing RCS reduction schemes often rely on complex absorbing structures or materials or complex back-end modulation modules, making it difficult to achieve efficient scattering reduction while maintaining the low profile and wideband radiation characteristics of strongly coupled arrays. How to achieve dynamic reconfiguration of array scattering characteristics through highly integrated array diode design without increasing the profile height or sacrificing radiation gain is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0006] To address the high in-band radar cross section (RCS) of existing strongly coupled array antennas, and the problems associated with traditional RCS reduction techniques (such as adding absorbing materials and reshaping the antenna shape) including heavy weight, high loss, and negative impact on radiation performance, this invention proposes a time-modulated low-scattering strongly coupled broadband array antenna with integrated diodes in the array surface. While maintaining the low profile and wide-band radiation characteristics of the strongly coupled array, this invention achieves time modulation and spectrum shifting of the in-band scattered field by introducing time-varying switch control into the array surface, effectively reducing the antenna's RCS within the operating frequency band.

[0007] To achieve the aforementioned objectives, the present invention employs the following technical solution: a time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes, comprising a wide-angle impedance matching layer, a plurality of strongly coupled dipole elements, and a metal reflector ground plane integrating a microstrip power divider; the plurality of strongly coupled dipole elements are arranged in a rectangular grid, with their tops inserted and fixed to the wide-angle impedance matching layer and their bottoms inserted and fixed to the metal reflector ground plane; each strongly coupled dipole element comprises a dielectric substrate, a dipole radiating body printed on the substrate, a parasitic metal patch, a feed balun structure, bias circuit traces, and a group of switching diodes and lumped elements mounted on the substrate; the switching diode group comprises a first switching diode group and a second switching diode group; the first switching diode group is loaded between the end of the dipole radiating body and the parasitic metal patch to control the magnitude of the inter-coupling capacitance; the second switching diode group is loaded at the connection between the feed balun structure and the dipole radiating body to switch the feed mode.

[0008] Furthermore, the dielectric substrate of the strongly coupled dipole unit is a double-sided copper-clad laminate, and its layer distribution characteristics are as follows: the first surface (front) is printed with the dipole radiating body, parasitic metal patch, microstrip line portion of the feed balun structure, and bias circuit traces, and the switching diode group, lumped inductor, and lumped capacitor are all mounted on this surface; the second surface (back) is printed with the ground structure of the feed balun structure and feed branches; the electrical connection between the first surface and the second surface is achieved through metallized vias.

[0009] Furthermore, the antenna has a specific bias link loop, the connection of which is as follows: the positive terminal of the bias signal enters the unit through the bias interface, is transmitted along the printed high-impedance line, passes through the low-pass filter composed of the mounted lumped inductor and lumped capacitor, and is connected to the two arms of the dipole radiating body, and finally connected to the positive terminals of the four switching diodes through the two arms; the negative terminals of the diodes of the second switching diode group are connected to the ground structure of the feed balun structure located on the back through metallized vias, and finally flow back to the ground layer electrically connected to the metal reflector; the negative terminals of the diodes of the first switching diode group are connected to the parasitic metal patch, and are electrically connected to the metal reflector through the high-impedance line printed on the patch layer, forming a closed loop.

[0010] Furthermore, the switching mechanism of the second switching diode group and its corresponding feeding mode is as follows: when the second switching diode group is turned on, the current of the feeding balun structure is mainly fed into the dipole radiating body in the form of direct current through the metallized via and the diode, forming a "direct electrical connection feeding" mode; when the second switching diode group is turned off, the current of the feeding balun structure is mainly coupled through the distributed capacitance between the feeding stub on the back and the dipole radiating body, forming a "stub coupling feeding" mode.

[0011] Furthermore, the first switching diode group and its corresponding coupling mechanism are as follows: the parasitic metal patch is a long strip metal patch printed close to the edge of the unit; when the array is assembled, the parasitic metal patch of this unit and the corresponding parasitic metal patch of the adjacent unit form an extremely narrow gap, constituting an inter-unit coupling capacitor; when the first switching diode group is turned on, the capacitor formed by the parasitic metal patch is connected in parallel to the two ends of the strong coupling dipole, changing the strong coupling strength between units.

[0012] Furthermore, the present invention adds a switching timing bias current to the switching diode group, causing it to operate at a frequency... Periodic switching is performed to achieve approximate binary phase-shift keying (BPSK) modulation of the scattered field. Specifically, in both "direct electrical connection feeding" and "stub-coupled feeding" states, the amplitude of the scattered field of the antenna element to the incident wave is approximately equal, but the phase difference of the scattered field is about 180 degrees. Through this phase modulation mechanism, the scattered field energy originally concentrated at the center carrier frequency (RF) is shifted to... At higher harmonics (n is a non-zero integer), the radar cross section (RCS) of the antenna at the operating center frequency is significantly reduced.

[0013] The beneficial effects of this invention are as follows: 1. This invention differs from traditional absorbing material loading technology by using low-loss time modulation technology. In the 2-3GHz operating frequency band, under the premise of ensuring that the antenna radiation gain and standing wave performance are not significantly degraded, it achieves a significant reduction in in-band co-polarization RCS. The array achieves a wide-angle scanning capability of 60 degrees in the E plane and 30 degrees in the H plane within 1.5 octaves, and has the dual advantages of broadband radiation and low scattering.

[0014] 2. Through a meticulously designed dual-switching mechanism of feeding and coupling, an approximately 180-degree phase reversal and equal amplitude characteristic of the scattered field are achieved in both states, constructing a highly efficient BPSK modulation effect and greatly improving the efficiency of transferring scattered energy to higher harmonics. 3. This invention employs a highly integrated array design, utilizing double-sided printed circuit technology to integrate the radiating unit, balun, bias network, and diode modulation circuitry onto a single dielectric substrate surface. This eliminates the need for additional vertical space or back-end modules, perfectly maintaining the low profile and compact architecture advantages of a strongly coupled array while achieving time modulation functionality. Attached Figure Description

[0015] Figure 1 The diagram shows the three-dimensional structural decomposition of the unit of the time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes provided by the present invention, as well as its matrix array assembly diagram.

[0016] Figure 2This is a schematic diagram of the metal layer layout on the first surface (front) of the dielectric substrate of the strongly coupled dipole unit in an embodiment of the present invention (showing the dipole radiating body, parasitic patch and part of the switching circuit).

[0017] Figure 3 This is a schematic diagram of the metal layer layout on the second surface (back side) of the dielectric substrate of the strongly coupled dipole unit in an embodiment of the present invention (showing the feeding balun structure and feeding branches).

[0018] Figure 4 This is a schematic diagram of the metal reflective floor structure in an embodiment of the present invention.

[0019] Figure 5 shows the voltage standing wave ratio (VSWR) curves of the center port when scanning in the E-plane and H-plane when the antenna elements form a 10x10 array in the embodiment of the present invention. (a) Comparison of E-plane scanning; (b) Comparison of H-plane scanning.

[0020] Figure 6 shows a comparison of the radiation gain versus frequency under two scanning conditions: E-plane and H-plane, when the antenna elements form a 10x10 array in the embodiment of the present invention. (a) Comparison of E-plane scanning; (b) Comparison of H-plane scanning.

[0021] Figure 7 shows the scanning patterns in the E-plane and H-plane scanning scenarios when the antenna elements form a 10x10 array in an embodiment of the present invention. (a) Comparison of E-plane scanning at the center frequency; (b) Comparison of H-plane scanning at the center frequency.

[0022] Figure 8 shows a comparison of the static scattered field response of the incident wave in two switching states when the antenna elements form a 10x10 array in an embodiment of the present invention. (a) Amplitude comparison; (b) Phase comparison.

[0023] Figure 9 This is a comparison diagram of the RCS of a single station with the same polarization in the same frequency band compared to a static, unmodulated array when a timing modulation signal is applied to an antenna array of 10x10 size. Detailed Implementation Plan

[0024] The specific embodiments of the present invention will now be described with reference to the accompanying drawings to facilitate understanding of the invention by those skilled in the art. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected. Furthermore, although this embodiment uses a 10×10 array as an example to demonstrate performance, in practical applications, the array unit can be periodically expanded to any scale on a two-dimensional plane according to actual aperture requirements, while maintaining the same working principle and performance advantages.

[0025] like Figure 1 As shown, the present invention provides a time-modulated low-scattering, strongly coupled broadband array antenna with integrated diode arrays. Its overall mechanical structure presents an "I"-shaped stacked architecture, mainly composed of an upper wide-angle impedance matching layer (1), a vertically inserted strongly coupled dipole unit (2) in the middle, and a bottom metal reflector ground plane (3). Both the wide-angle impedance matching layer (1) and the metal reflector ground plane (3) are integral structures, with matching slots for each unit on the plate. The strongly coupled dipole unit (2) is inserted upwards into the wide-angle impedance matching layer (1) through its top slot and downwards into the metal reflector ground plane (3) through its bottom slot, forming a stable array structure. In this embodiment, the array unit spacing (lattice size) along both the x and y directions is 45 mm. This spacing design comprehensively considers grating lobe suppression and mutual coupling strength within the operating frequency band.

[0026] like Figure 2 and Figure 3 As shown, the core circuit of the strongly coupled dipole unit (2) is fabricated on a double-sided copper-clad dielectric substrate with a dielectric constant of 2.2 and a thickness of 1 mm. The first surface (front) of the dielectric substrate is printed with a dipole radiating body (211) and parasitic metal patches (206) and (210). The parasitic metal patches (206) and (210) are elongated strips and printed close to the edge of the unit. When the array is assembled, the dipole radiating body and parasitic metal patches of this unit form an extremely narrow gap with the corresponding structure of the adjacent unit, thereby introducing strong inter-unit capacitive coupling, which is the physical basis for realizing broadband characteristics. The second surface (back) of the dielectric substrate is printed with the ground structure of the feed balun structure (212) and the feed stubs. The feed balun structure (212) adopts the Marchand balun design. Through the cooperation of the gradient microstrip line on the front and the ground structure on the back, it realizes efficient impedance transformation and mode transformation from a 50-ohm coaxial input to a balanced dipole.

[0027] To achieve time modulation of the antenna's scattering characteristics, this embodiment incorporates a PIN diode-based switching control circuit on the antenna element. For example... Figure 2As shown, in this embodiment, the diode group uses MADP-000907-14020 PIN diodes, but it is not limited to this; any switching element that exhibits low resistance characteristics after conduction can be used. Among them, the first switching diode group (203) and (204) are mounted on the front side and connected between the end of the dipole radiating body (211) and the parasitic metal patches (206) and (210). When the first switching diode group is turned on, the inter-board capacitance formed by the parasitic metal patches is connected in parallel to the two ends of the dipole, changing the coupling strength between the units; when it is turned off, the coupling becomes weaker. The second switching diode group (201) and (202) are mounted at the feed position, with their positive terminals connected to the dipole radiating body (211) and their negative terminals connected to the feed balun structure (212) on the back side through metallized vias. When the second switching diode group is turned on, the balun current is directly injected into the dipole through the metal wire, forming a "direct electrical connection feeding" mode; when it is turned off, the balun is disconnected from the dipole by DC, and the current is mainly coupled through the distributed capacitance between the back-side feeding stub and the dipole, forming a "stub-coupled feeding" mode. The first and second switching diode groups operate synchronously under the drive of the same timing bias signal, thereby realizing the overall switching between the 'on state' and 'off state' in the entire unit.

[0028] To provide a high-speed time-varying drive signal for the aforementioned PIN diodes, this embodiment designs a highly integrated bias link. The positive bias signal enters through the bias interface (209) at the bottom and is transmitted along the printed high-impedance line (207). To isolate the RF signal from the DC bias signal, a low-pass filter consisting of a lumped inductor (205) and a lumped capacitor (208) connected in parallel to ground is connected in series along the path. The cutoff frequency of this filter is set to about 150MHz, which is far below the antenna's 2-3GHz operating frequency band, while still meeting the requirements for passing through MHz-level modulation frequencies. After the bias current flows through the diodes, it returns through two paths: the first path flows through the second switching diode group (201), (202) and vias to the back balun ground, and finally merges into the metal reflective ground (3); the second path flows through the first switching diode group (203), (204) to the parasitic metal patch, and is connected to the metal reflective ground (3) through the high-impedance line extended from the patch layer, thus forming a complete closed loop.

[0029] Furthermore, to further optimize the wide-angle scanning performance of the array, the wide-angle impedance matching layer (1) located at the top of the array is made of a high-frequency dielectric substrate with a dielectric constant of 3 and a thickness of 2 mm. This matching layer not only serves as the mechanical support structure of the array but also acts as a dielectric cover layer, effectively improving the impedance matching characteristics of the array during large-angle scanning. Figure 4As shown, the metal reflective floor (3) is engraved with grooves and openings that can just accommodate the coupled dipole unit (2) for inserting and fixing the plate, and at the same time serving as the reference ground plane for the entire array.

[0030] Figure 5 shows the simulation results of the active voltage standing wave ratio (VSWR) of the unit port in this embodiment under two switching states. The data shows that within the 2.0-3.0 GHz operating frequency band, the average VSWR of the antenna element in the side-firing (0 degrees) direction is below 1.7, regardless of whether the diode is in the on state (direct feeding) or the off state (coupled feeding). Even at large angles such as E-plane scanning to 60 degrees and H-plane scanning to 30 degrees, the active VSWR at most frequencies within the band remains stable and reliable (average VSWR in the off state is 1.65 when scanning at 60 degrees on the E-plane and 2.07 when scanning at 30 degrees on the H-plane). This indicates that the present invention maintains the broadband and wide-angle scanning impedance matching characteristics of the strongly coupled array despite the introduction of complex switching circuitry.

[0031] Figures 6 and 7 further illustrate the radiation gain characteristics of the array. Statistical results show that within the 2-3 GHz band, the difference in main polarization gain between the diode's on-state and off-state is minimal. The average gain difference during E-plane scanning is only 0.26 dB to 0.41 dB, and the average gain difference during H-plane scanning is also controlled within 0.45 dB. This means that during time modulation (i.e., rapid switching between these two states), the antenna's amplitude modulation of the transmitted / received signal (radiation mode) is minimal, ensuring the stability of communication or radar detection. Simultaneously, the array maintains good cross-polarization isolation in both the E-plane and H-plane, with an average isolation better than 20 dB.

[0032] Figure 8 reveals the core mechanism by which this invention achieves low scattering. By comparing the static scattering response of the antenna element to the incident wave in both diode-on and diode-off states, it can be found that within the 2.0-3.0 GHz frequency band, the scattered field amplitude (RCS) in both states is very close (average -1.09 dBsm in the on state and -2.53 dBsm in the off state, with little difference), while the phase difference of the scattered field exhibits a characteristic of fluctuating around 180 degrees (average phase difference of -157.38 degrees, standard deviation of 21.62 degrees). This characteristic of "approximately equal amplitude and opposite phase" constitutes a near-ideal binary phase-shift keying (BPSK) modulation condition. Meanwhile, although the scattered field amplitude is approximately equal in both states, a slight amplitude imbalance still exists. To maximize the RCS reduction effect at the center carrier frequency (RF), this embodiment optimizes the duty cycle of the switching timing signal. By setting the pulse duty cycle to 30% (instead of the traditional 50%), the scattered field vectors under the two states are weighted and compensated using the time integration principle, so that the vector sum of the scattered field (i.e., the zeroth harmonic component) within one modulation period approaches zero. This asymmetric modulation strategy based on duty cycle optimization effectively corrects the carrier residue caused by amplitude imbalance.

[0033] Figure 9 This demonstrates the single-station RCS reduction effect of the 10×10 array in this embodiment after applying a 5 MHz pulse-time modulation signal with a 30% duty cycle. Thanks to the aforementioned BPSK modulation mechanism, the scattered energy originally concentrated at the center carrier frequency (fundamental wave) is shifted to... The high-order harmonic components are reduced, thereby decreasing the scattered signal energy at the original frequency. Test data shows that compared to a metal plate (PEC) of the same size, this invention achieves an average RCS reduction of 29.54 dB; compared to a static, unmodulated array antenna, this invention achieves an average RCS reduction of 12.65 dB within the band, with a maximum reduction of 23.55 dB. This fully demonstrates that the time modulation technology of the array-integrated diode proposed in this invention can effectively reduce the radar cross-section of a strongly coupled broadband array within the operating frequency band, significantly improving the stealth performance of the antenna system.

Claims

1. A time-modulated, low-scattering, strongly coupled broadband array antenna with integrated diodes, characterized in that, include: The array comprises a wide-angle impedance matching layer (1), several strongly coupled dipole units (2), and a metal reflector ground plane (3) for an integrated microstrip power divider; the several strongly coupled dipole units (2) are arranged in a rectangular grid, with their tops inserted and fixed to the wide-angle impedance matching layer (1) and their bottoms inserted and fixed to the metal reflector ground plane (3); each strongly coupled dipole unit (2) includes a dielectric substrate, a dipole radiating body (211) printed on the substrate, parasitic metal patches (206, 210), a feed balun structure (212), a bias network interface and traces (207, 209), and a switching diode group (201-204) and lumped elements (205, 208) mounted on the array substrate; the switching diode group includes a first switching diode group (203, 204) and a second switching diode group (201, 202); the first switching diode group is loaded at the end of the dipole radiating body (211) and the parasitic metal patch (206, 210), Between 210), the size of the coupling capacitor between the control units is controlled; the second switching diode group is loaded at the connection between the feed balun structure (212) and the dipole radiating body (211) to switch the feed mode; the bias network interface and traces (207, 209) required by the switch control circuit are configured to receive timing bias signals to control the on / off state of the first switching diode group and the second switching diode group, so as to realize the time modulation of the antenna array scattering field.

2. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The dielectric substrate of the strongly coupled dipole unit (2) is a double-sided copper-clad laminate, and its layer distribution features are as follows: First surface (front): The dipole radiating body (211), parasitic metal patches (206, 210), microstrip line portion of the feed balun structure (212) and bias circuit trace (207) are printed on it; The switching diode group (201-204), lumped inductor (205) and lumped capacitor (208) are all mounted on this surface; Second surface (back): The ground structure of the feed balun structure (212) and feed branches are printed on it; The electrical connection between the first surface and the second surface is achieved through metallized vias.

3. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The antenna has a specific bias link loop, and its connection relationship is as follows:

1. Bias Input Path: The positive terminal of the bias signal enters the unit through the bias interface (209), is transmitted along the printed high impedance line (207), passes through the series lumped inductor (205), and is connected to the two arms of the dipole radiating body (211), and finally connected to the positive terminals of the four switching diodes (201-204). One end of the lumped capacitor (208) is connected to the high impedance line (207), and the other end is grounded, forming a low-pass filter; Bias Return Path 1 (Feed Control Circuit): The negative terminals of the diodes (201, 202) of the second switching diode group are connected to the ground structure of the feed balun structure (212) located on the back through metallized vias, and finally flow back to the ground layer electrically connected to the metal reflector plate (3); Bias Return Path 2 (Coupling Control Circuit): The negative terminals of the diodes (203, 204) of the first switching diode group are connected to the parasitic metal patch (206, 210), and is electrically connected to the metal reflective ground plane (3) by means of high resistance lines printed on the patch layer, such as plug-in contacts, conductive solder or conductive glue, to form a closed loop.

4. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 3, characterized in that, The parameters of the low-pass filter are set as follows: its cutoff frequency is set to be greater than the time modulation frequency and much smaller than the radio frequency operating frequency, so as to achieve isolation between the DC bias signal and the radio frequency signal.

5. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The first switching diode group (203, 204) and its corresponding coupling mechanism are as follows: The parasitic metal patch (206, 210) is a long strip metal patch printed close to the edge of the unit; When the array is assembled, the parasitic metal patch of this unit and the corresponding parasitic metal patch of the adjacent unit form an extremely narrow gap, constituting the inter-unit coupling capacitor; When the first switching diode group (203, 204) is turned on, the capacitor formed by the parasitic metal patch is connected in parallel to the two ends of the strong coupling dipole, changing the strong coupling strength between units.

6. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The second switching diode group (201, 202) and its corresponding feeding mode switching mechanism are as follows: When the second switching diode group is turned on, the current of the feeding balun structure (212) is fed into the dipole radiating body (211) in the form of direct current through the metallized via and the diode, forming a "direct electrical connection feeding" mode; When the second switching diode group is turned off, the current of the feeding balun structure (212) is coupled through the distributed capacitance between the feeding stub on the back and the dipole radiating body (211), forming a "stub coupling feeding" mode.

7. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The time modulation mechanism of the antenna array's scattered field is as follows: the control terminal applies a frequency to the switching diode group. The periodic switching timing bias current causes the antenna to periodically switch between two modes. Utilizing the characteristic that the phase difference between the scattered fields in the two modes is approximately 180 degrees, and by adjusting the duty cycle of the switching timing to compensate for the amplitude difference of the scattered fields in the two modes, the vector sum of the scattered fields at the center carrier frequency within the modulation period is minimized; through this modulation, the scattered field energy is shifted from the center carrier frequency (RF) to... At higher harmonics (n is a positive integer), the radar cross section (RCS) of the antenna at the original frequency of the incident wave is reduced.

8. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The feeding balun structure (212) is a broadband balun that mainly adopts the Marchand balun structure; Its front-printed gradient microstrip line enables impedance transformation from 50-ohm coaxial feed to balanced dipole feed.

9. The time-modulated low-scattering, strongly coupled broadband array antenna with integrated diodes according to claim 1, characterized in that, The mechanical assembly structure of the array is as follows: the wide-angle impedance matching layer (1) and the metal reflective ground (3) are both integral structures, and slots are opened on the plate corresponding to each unit position; the strong coupling dipole unit (2) is vertically inserted into the slots, and the ground connection point of the feed balun structure (212) in the unit is electrically and mechanically connected to the metal reflective ground (3), together forming a stable array structure.

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