2bit time modulation circuit integrated with air-filled siw filter

Abstract

The application discloses a 2bit time modulation circuit integrated with an air-filled SIW filter, which comprises a first-stage time modulation circuit, a first coupling window, an air-filled SIW filter, a second-stage time modulation circuit, a second coupling window, an input port and an output port, the input port is connected with the first-stage time modulation circuit, the first-stage time modulation circuit is connected with the first coupling window and then connected with the air-filled SIW filter, the air-filled SIW filter is connected with the second coupling window, the second coupling window is connected with the second-stage time modulation circuit, and the second-stage time modulation circuit is connected with the output port. The filter structure in the application not only has the characteristics of narrow bandwidth and low loss, but also integrates the phase shift advantage of the time modulation circuit, is applied to a time modulation array, can effectively improve the weak problem that the time modulation array itself suppresses useless harmonics, is consistent with actual engineering requirements, and has important theoretical and practical significance.

Description

Technical Field

[0001] This invention relates to the field of wireless mobile communication technology, and in particular to a 2-bit time modulation circuit with an integrated air-filled SIW filter. Background Technology

[0002] With the rapid development of wireless communication technology, radio frequency (RF) front-end systems are evolving towards high performance, high integration, and low loss. Traditionally, passive components in RF front-ends, such as filters, antennas, and duplexers, are designed separately and cascaded. This inevitably leads to large physical dimensions, complex circuitry, high insertion loss, and signal distortion. The inherent switching behavior of traditional time modulation generates unwanted harmonic sidebands in the frequency domain. These sideband signals not only cause energy dispersion but also interfere with the main signal, resulting in spectral aliasing that severely restricts the antenna's operating bandwidth and dynamic range. Therefore, it is necessary to reduce unwanted harmonic sidebands in time modulation, clean up the spectrum, ensure independent beam generation, and reduce inter-beam interference. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a 2-bit time modulation circuit with an integrated air-filled SIW filter. The proposed integrated filter structure features narrow bandwidth, low loss, and the phase-shifting advantage of the integrated time modulation circuit. When applied to a time modulation array, it improves the weak suppression of unwanted harmonics by the time modulation array itself, which aligns with practical engineering requirements and has significant theoretical and practical implications.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A 2-bit time modulation circuit for an integrated air-filled SIW filter includes:

[0006] The circuit comprises a first-stage time modulation circuit, a first coupling window, an air-filled SIW filter, a second-stage time modulation circuit, a second coupling window, an input port, and an output port. The input port is connected to the first-stage time modulation circuit. The first-stage time modulation circuit is connected to the first coupling window and then to the air-filled SIW filter. The air-filled SIW filter is connected to the second coupling window. The second coupling window is connected to the second-stage time modulation circuit. The second-stage time modulation circuit is connected to the output port.

[0007] The first-stage time modulation circuit and the second-stage time modulation circuit have the same structure, both including a first metal layer, a first dielectric substrate and a second metal layer. The first dielectric substrate is disposed on the lower surface of the first metal layer and the second metal layer is disposed on the lower surface of the first dielectric substrate.

[0008] The air-filled SIW filter includes a third metal layer, a second dielectric substrate, a fourth metal layer, a fifth metal layer, a third dielectric substrate, and a sixth metal layer. The third metal layer is disposed on the lower surface of the second metal layer, the second dielectric substrate is disposed on the lower surface of the third metal layer, the fourth metal layer is disposed on the lower surface of the second dielectric substrate, the fifth metal layer is disposed on the lower surface of the fourth metal layer, the third dielectric substrate is disposed on the lower surface of the fifth metal layer, and the sixth metal layer is disposed on the lower surface of the third dielectric substrate.

[0009] The first coupling window and the second coupling window are disposed on the second metal layer.

[0010] As a preferred technical solution of the present invention: the first metal layer includes a metal sheet, a power supply port, a metal pad, a first metal phase shifter, a second metal phase shifter, a third metal phase shifter, a fourth metal phase shifter, a metal coupling line, and an RF single-pole double-throw switch;

[0011] The spacing between the metal sheet, the power supply port, the metal pad, the first metal phase shift line, the second metal phase shift line, the third metal phase shift line, the fourth metal phase shift line, and the metal coupling line is all formed by slots;

[0012] The RF single-pole double-throw switch has six pins connected to metal pads. The RF single-pole double-throw switch periodically switches the direction path to the first metal phase shift line, the second metal phase shift line, the third metal phase shift line, and the fourth metal phase shift line to achieve filtering and phase shifting functions of 0°, 90°, 180°, and 270°.

[0013] The metal sheet is provided with large metal vias and small metallized vias.

[0014] As a preferred embodiment of the present invention: the first dielectric substrate is provided with a first dielectric via, a second dielectric via, a third dielectric via, a fourth dielectric via, and a fifth dielectric via.

[0015] The first dielectric via is a metallized via, which is arrayed in the edge region of the filter structure to realize the electrical interconnection between the first metal layer and the second metal layer;

[0016] The second medium through hole is a non-metallized through hole, used to fix the SMA connector;

[0017] The third dielectric via is a metallized via, used to connect the first metal phase shift line, the third metal phase shift line, and the second metal layer;

[0018] The fourth dielectric via is a metallized via, used to achieve the connection between the metal pads in the first metal layer and the second metal layer;

[0019] The fifth dielectric via is a non-metallized via, used to achieve mechanical fixation of the filter.

[0020] As a preferred embodiment of the present invention: the second metal layer is provided with a first mounting through hole, a second mounting through hole, a third coupling window, and a third mounting through hole.

[0021] The first mounting via is a metallized via, corresponding to the position of the first dielectric via on the first dielectric substrate;

[0022] The second mounting through hole is used to secure the SMA connector;

[0023] The third coupling window is symmetrical about the center line of the long side of the second metal layer, and is used to realize the electromagnetic coupling between the upper feed network and the lower SIW resonant cavity.

[0024] The third mounting via is a non-metallized via, and its position corresponds to the position of the fifth dielectric via on the first dielectric substrate, thereby achieving mechanical fixation of the filter.

[0025] As a preferred embodiment of the present invention: the third metal layer is provided with a first fixing through hole, a second fixing through hole, a third fixing through hole, and a first square air cavity.

[0026] The first fixed through hole is a metallized through hole, which is periodically arranged around the air resonant cavity;

[0027] The second fixing through hole corresponds to the position of the third mounting through hole of the second metal layer, so as to realize the mechanical fixation of the filter;

[0028] The third fixing through hole is used to fix the SMA connector;

[0029] The first square air cavity achieves electromagnetic coupling through the central coupling gap of the third metal layer.

[0030] As a preferred embodiment of the present invention: the second dielectric substrate is provided with a first substrate through-hole, a second substrate through-hole, a third substrate through-hole, and a second square air cavity.

[0031] The first substrate vias are metallized vias, arranged periodically around the air resonant cavity to form a closed metal cavity;

[0032] The second substrate via is a non-metallized via, which corresponds to the position of the third mounting via of the second metal layer, and is used to achieve mechanical fixation of the filter;

[0033] The through-hole in the third substrate is used to fix the SMA connector;

[0034] The second square air cavity achieves electromagnetic coupling through the central coupling gap of the second dielectric substrate.

[0035] As a preferred embodiment of the present invention: the fourth metal layer is provided with a first metal through-hole, a second metal through-hole, a third metal through-hole, and a third shaped air cavity.

[0036] The first metal via is a metallized via, arranged periodically around the air resonant cavity;

[0037] The second metal through-hole corresponds to the third mounting through-hole of the second metal layer, which is used to achieve mechanical fixation of the filter;

[0038] The third metal through hole is used to fix the SMA connector;

[0039] The third-dimensional air cavity achieves electromagnetic coupling through the central coupling gap of the fourth metal layer.

[0040] As a preferred embodiment of the present invention: the fifth metal layer, the third dielectric substrate, and the sixth metal layer are provided with a first metal layer through hole, a first through hole, and a first flange through hole at corresponding positions.

[0041] The first metal layer through hole, the first through hole, and the first flange through hole are non-metallized through holes, and their positions correspond to the second metal through hole of the fourth metal layer, so as to achieve mechanical fixation of the filter;

[0042] The fifth metal layer, the third dielectric substrate, and the sixth metal layer are provided with a second metal layer through hole, a second through hole, and a second flange through hole at corresponding positions. The second metal layer through hole, the second through hole, and the second flange through hole are non-metallic through holes used to fix the SMA connector.

[0043] As a preferred embodiment of the present invention, the first-stage time modulation circuit and the second-stage time modulation circuit are provided with periodic control signals by the same timing control module.

[0044] As a preferred embodiment of the present invention: the center frequency of the air-filled SIW filter is consistent with the target operating sideband frequency of the first-stage time modulation circuit and the second-stage time modulation circuit, and the passband width of the air-filled SIW filter is smaller than the frequency interval between adjacent non-operating harmonic sidebands.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. This invention innovatively utilizes the high Q value of an air-filled SIW filter to achieve extremely narrow bandwidth while maintaining low loss. When applied to time modulation, it effectively suppresses time modulation harmonics. At the same time, the 2-bit time modulation circuit used is integrated into the filter, and four phase shift states are switched and the filtering effect is achieved by using an RF switch, which reduces the physical size compared to direct cascading.

[0047] 2. This invention integrates a 2-bit time modulation circuit with a filter. By utilizing RF switching elements loaded on the input and output feed lines, it can achieve phase shifts of 0°, 90°, 180° and 270° of the 2-bit time modulation circuit and periodically switch states through time modulation. It can also achieve the advantages of the filter, such as narrow bandwidth, low loss and high harmonic suppression.

[0048] 3. This invention integrates a 2-bit time modulation circuit with an air-filled SIW filter. By utilizing the suppression effect of the filter, it achieves efficient suppression of unwanted harmonics in the time modulation circuit, reducing unwanted harmonics in the time modulation circuit from a maximum of -9.54dB to -35.14dB. Other unwanted harmonics are also suppressed to below -40dB, thus purifying the spectrum and avoiding interference from these unwanted harmonics to the time modulation array. At the same time, the filter's low loss advantage has a small impact on the operating sideband of the time modulation circuit, achieving significant suppression of other unwanted sidebands while retaining the operating sideband. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention.

[0050] Figure 2 This is an exploded view of the present invention.

[0051] Figure 3 This is the S-parameter curve of the 2-bit time modulation circuit of the integrated air-filled SIW filter of this invention.

[0052] Figure 4 This is the normalized output power spectrum of the 2-bit time modulation circuit before integration in this invention.

[0053] Figure 5 This is the normalized output power spectrum of the air-filled SIW filter after the integrated 2-bit time modulation circuit of this invention.

[0054] Figure 6 This is a diagram showing the 90° phase shift effect of the 2-bit time modulation circuit in this invention.

[0055] Figure 7 This is the 180° phase shift effect of the 2-bit time modulation circuit in this invention.

[0056] Figure 8This is the 270° phase shift effect of the 2-bit time modulation circuit in this invention.

[0057] Figure 9 This is a structural diagram of the time modulation array antenna composed of the present invention.

[0058] Figure 10 The normalized gain pattern of each harmonic sideband of the time modulation array antenna is composed of a 2-bit time modulation circuit with an unloaded air-filled SIW filter according to the present invention.

[0059] Figure 11 The normalized gain pattern of each harmonic sideband of the time modulation array antenna is composed of a 2-bit time modulation circuit integrating an air-filled SIW filter, as described in this invention.

[0060] List of reference numerals in the attached diagram:

[0061] 1. First-stage time modulation circuit; 2. First coupling window; 3. Air-filled SIW filter; 4. Second-stage time modulation circuit; 5. Second coupling window; 6. Input port; 7. Output port;

[0062] 100. First metal layer; 101. Metal sheet; 102. Small metallized via; 103. Large metal via; 104. Power supply port; 105. Metal pad; 106. First metal phase shifter; 107. Second metal phase shifter; 108. Metal coupling line; 109. RF single-pole double-throw switch; 110. Third metal phase shifter; 111. Fourth metal phase shifter;

[0063] 200, First dielectric substrate; 201, First dielectric via; 202, Second dielectric via; 203, Third dielectric via; 204, Fourth dielectric via; 205, Fifth dielectric via;

[0064] 300, Second metal layer; 301, First mounting through hole; 302, Second mounting through hole; 303, Third coupling window; 304, Third mounting through hole;

[0065] 400, Third metal layer; 401, First fixing through hole; 402, Second fixing through hole; 403, Third fixing through hole; 404, First square air cavity;

[0066] 500, Second dielectric substrate; 501, Through-hole of first substrate; 502, Through-hole of second substrate; 503, Through-hole of third substrate; 504, Second square air cavity;

[0067] 600, Fourth metal layer; 601, First metal via; 602, Second metal via; 603, Third metal via; 604, Third shaped air cavity;

[0068] 700, Fifth metal layer; 701, First metal layer via; 702, Second metal layer via;

[0069] 800, Third dielectric substrate; 801, First through-hole; 802, Second through-hole;

[0070] 900, Sixth metal layer; 901, First flange through hole; 902, Second flange through hole. Detailed Implementation

[0071] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0072] like Figure 1 This invention proposes a 2-bit time modulation circuit for an integrated air-filled SIW filter, comprising:

[0073] The circuit comprises a first-stage time modulation circuit 1, a first coupling window 2, an air-filled SIW filter 3, a second-stage time modulation circuit 4, a second coupling window 5, an input port 6, and an output port 7. The input port 6 is connected to the first-stage time modulation circuit 1. The first-stage time modulation circuit 1 is connected to the first coupling window 2 and then to the air-filled SIW filter 3. The air-filled SIW filter 3 is connected to the second coupling window 5. The second coupling window 5 is connected to the second-stage time modulation circuit 4. The second-stage time modulation circuit 4 is connected to the output port 7.

[0074] The first-stage time modulation circuit 1 and the second-stage time modulation circuit 4 have the same structure, both including a first metal layer 100, a first dielectric substrate 200 and a second metal layer 300. The first dielectric substrate 200 is disposed on the lower surface of the first metal layer 100 and the second metal layer 300 is disposed on the lower surface of the first dielectric substrate 200.

[0075] The air-filled SIW filter 3 includes a third metal layer 400, a second dielectric substrate 500, a fourth metal layer 600, a fifth metal layer 700, a third dielectric substrate 800, and a sixth metal layer 900. The third metal layer 400 is disposed on the lower surface of the second metal layer 300, the second dielectric substrate 500 is disposed on the lower surface of the third metal layer 400, the fourth metal layer 600 is disposed on the lower surface of the second dielectric substrate 500, the fifth metal layer 700 is disposed on the lower surface of the fourth metal layer 600, the third dielectric substrate 800 is disposed on the lower surface of the fifth metal layer 700, and the sixth metal layer 900 is disposed on the lower surface of the third dielectric substrate 800.

[0076] The first coupling window 2 and the second coupling window 5 are disposed on the second metal layer 300.

[0077] When a signal is input through input port 6, the first-stage time modulation circuit 1 acts as a feeder and a delayed phase-shifting line. The energy is coupled to the air-filled SIW filter 3 through the first coupling window 2, and then coupled to the second-stage time modulation circuit 4 through the second coupling window 5. Finally, the signal is output through output port 7, thus realizing the integration of the air-filled SIW filter 3 and the 2-bit time modulation circuit.

[0078] The first-stage time modulation circuit 1 and the second-stage time modulation circuit 4 are provided with periodic control signals by the same timing control module. Multiple 2-bit time modulation circuits are respectively connected to the front end of each antenna element of the time modulation array antenna, and are provided with periodic control signals by the same timing control module to form the working sideband beam and suppress the non-working sideband beam.

[0079] The center frequency of the air-filled SIW filter 3 is consistent with the target operating sideband frequency of the first-stage time modulation circuit 1 and the second-stage time modulation circuit 4, and the passband width of the air-filled SIW filter 3 is smaller than the frequency interval between adjacent non-operating harmonic sidebands.

[0080] This invention innovatively utilizes the high Q value of the air-filled SIW filter 3 to achieve extremely narrow bandwidth while maintaining low loss. When applied to time modulation, it effectively suppresses time modulation harmonics. At the same time, the 2-bit time modulation circuit used is integrated into the filter, and the four phase shift states and filtering effects are achieved by using an RF switch, which reduces the physical size compared to direct cascading.

[0081] like Figure 2 As shown, the specific structure of the present invention is as follows:

[0082] The first metal layer 100 includes four metal sheets 101, two power supply ports 104, four metal pads 105, a first metal phase shifter 106, a second metal phase shifter 107, a third metal phase shifter 110, a fourth metal phase shifter 111, two metal coupling lines 108, and four radio frequency single-pole double-throw switches 109.

[0083] The first metal layer 100, excluding the first metal phase shift line 106, the second metal phase shift line 107, the third metal phase shift line 110, and the fourth metal phase shift line 111, is arranged symmetrically about the center line of the long side of the first dielectric substrate 200.

[0084] The spacing between the four metal plates 101, the two power supply ports 104, the four metal pads 105, the first metal phase shift line 106, the second metal phase shift line 107, the third metal phase shift line 110, the fourth metal phase shift line 111, and the two metal coupling lines 108 is formed by slots.

[0085] Each of the six pins of the four RF single-pole double-throw switches 109 is connected to one of the four metal pads 105. The RF single-pole double-throw switches 109 periodically switch the direction path to the first metal phase shift line 106, the second metal phase shift line 107, the third metal phase shift line 110 and the fourth metal phase shift line 111 to achieve the filtering and phase shifting functions of 0°, 90°, 180° and 270°.

[0086] Each of the four metal plates 101 has a large metal via 103 and eleven small metallized vias 102.

[0087] The first dielectric substrate 200 is provided with a plurality of first dielectric vias 201, a plurality of second dielectric vias 202, a plurality of third dielectric vias 203, a plurality of fourth dielectric vias 204, and a plurality of fifth dielectric vias 205.

[0088] The first dielectric via 201 is a metallized via, which is arrayed in the edge region of the filter structure to realize the electrical interconnection between the first metal layer 100 and the second metal layer 300, thereby achieving a grounding effect.

[0089] The second medium through hole 202 is a non-metallic through hole used to fix the SMA connector;

[0090] The third dielectric via 203 is a metallized via used to connect the first metal phase shifter 106, the third metal phase shifter 110 and the second metal layer 300 to achieve a grounding effect;

[0091] The fourth dielectric via 204 is a metallized via used to connect the metal pad 105 in the first metal layer 100 to the second metal layer 300, thereby achieving grounding.

[0092] The fifth dielectric via 205 is a non-metallized via used to achieve mechanical fixation of the filter.

[0093] The second metal layer 300 is provided with a plurality of first mounting through holes 301, a plurality of second mounting through holes 302, two third coupling windows 303, and a plurality of third mounting through holes 304.

[0094] The first mounting via 301 is a metallized via, and its position corresponds to the first dielectric via 201 of the first dielectric substrate 200.

[0095] The second mounting through hole 302 is used to secure the SMA connector;

[0096] The third coupling window 303 is symmetrical about the midline of the long side of the second metal layer 300, and is used to realize the electromagnetic coupling between the upper feed network and the lower SIW resonant cavity.

[0097] The third mounting via 304 is a non-metallized via, and the position of the third mounting via 304 corresponds to the position of the fifth dielectric via 205 of the first dielectric substrate 200, so as to realize the mechanical fixation of the filter.

[0098] The third metal layer 400 is provided with a plurality of first fixing through holes 401, a plurality of second fixing through holes 402, a plurality of third fixing through holes 403, and two first square air cavities 404.

[0099] The first fixed through hole 401 is a metallized through hole, which is periodically arranged around the air resonant cavity;

[0100] The second fixing through hole 402 corresponds to the position of the third mounting through hole 304 of the second metal layer 300, so as to realize the mechanical fixing of the filter;

[0101] The third fixing through hole 403 is used to fix the SMA connector;

[0102] The first square air cavity 404 achieves electromagnetic coupling through the central coupling gap of the third metal layer 400.

[0103] The second dielectric substrate 500 is provided with a plurality of first substrate through holes 501, a plurality of second substrate through holes 502, a plurality of third substrate through holes 503, and two second square air cavities 504.

[0104] The first substrate via 501 is a metallized via, which is periodically arranged around the air resonant cavity to form a closed metal cavity;

[0105] The second substrate via 502 is a non-metallized via, which corresponds to the position of the third mounting via 304 of the second metal layer 300, and is used to achieve mechanical fixation of the filter.

[0106] The third substrate through-hole 503 is used to fix the SMA connector;

[0107] The second square air cavity 504 achieves electromagnetic coupling through the central coupling gap of the second dielectric substrate 500.

[0108] The fourth metal layer 600 is provided with a plurality of first metal through holes 601, a plurality of second metal through holes 602, a plurality of third metal through holes 603, and two third-shaped air cavities 604.

[0109] The first metal through-hole 601 is a metallized through-hole, which is periodically arranged around the air resonant cavity;

[0110] The second metal through-hole 602 corresponds to the third mounting through-hole 304 of the second metal layer 300, and is used to achieve mechanical fixation of the filter;

[0111] The third metal through-hole 603 is used to secure the SMA connector;

[0112] The third square air cavity 604 achieves electromagnetic coupling through the central coupling gap of the fourth metal layer 600.

[0113] The fifth metal layer 700, the third dielectric substrate 800, and the sixth metal layer 900 are provided with a plurality of first metal layer through holes 701, first through holes 801, and first flange through holes 901 at corresponding positions.

[0114] The first metal layer through hole 701, the first through hole 801, and the first flange through hole 901 are non-metallic through holes, and correspond to the position of the second metal through hole 602 of the fourth metal layer 600, so as to realize the mechanical fixation of the filter.

[0115] The fifth metal layer 700, the third dielectric substrate 800 and the sixth metal layer 900 are provided with a plurality of second metal layer through holes 702, second through holes 802 and second flange through holes 902 at corresponding positions. The second metal layer through holes 702, second through holes 802 and second flange through holes 902 are non-metallic through holes, which are used to fix the SMA connector.

[0116] The present invention will now be described in detail with reference to specific embodiments.

[0117] In this invention, by utilizing the RF switching element loaded on the input and output feed lines of the 2-bit time modulation circuit of the integrated air-filled SIW filter, it is possible to achieve phase shifts of 0°, 90°, 180° and 270° of the 2-bit time modulation circuit and periodically switch the state through time modulation. At the same time, it is possible to achieve narrow bandwidth, low loss and high harmonic suppression of the filter. Simultaneously, the suppression effect of the filter is used to achieve efficient suppression of unwanted harmonics of the time modulation circuit, retaining the working sideband while significantly suppressing other unwanted sidebands.

[0118] like Figure 3 The figure shows the S-parameter curve of the filter of the present invention. S(2,1) is the forward transmission coefficient / insertion loss from the first port to the second port of the device. The simulation results of the present invention show a -3dB bandwidth of 8MHz, a center frequency of 2.02GHz, and an insertion loss of 1.56dB. The positions of the unwanted harmonics in the power spectrum of the time modulation circuit on the S-parameter curve are separated by 4 times the modulation frequency (f). p=10MHz), the power spectrum of the time modulation circuit at 1.98GHz shows a suppression of -27.16dB for the -3rd order, -36.83dB for the -7th order, -41.42dB for the -11th order, -32.29dB for the +5th order, -47.52dB for the +9th order, and -51.91dB for the +13th order.

[0119] like Figure 4 The image shows the normalized output power spectrum of the 2-bit time modulation circuit before the integrated air-filled SIW filter. The center frequency is 2.02 GHz, the modulation frequency is 10 MHz, and only the (4k+1)th harmonic remains in the spectrum, with each harmonic spaced four times the modulation frequency 4f. p The main non-operating harmonics are -3rd, -7th, -11th, +5th, +9th, and +13th harmonics, with normalized amplitudes of -9.54dB, -16.09dB, -20.83dB, -13.98dB, -19.09dB, and -22.28dB, respectively. Further suppression is needed to avoid their interference.

[0120] like Figure 5 The image shows the normalized output power spectrum of the 2-bit time modulation circuit with an integrated air-filled SIW filter. The center frequency corresponds to the +1st operating harmonic at 2.02 GHz. The other remaining harmonics are at 1.98 GHz (-3rd), 1.94 GHz (-7th), 1.90 GHz (-11th), 2.06 GHz (+5th), 2.10 GHz (+9th), and 2.14 GHz (+13th). The harmonic levels after being suppressed by the filter are -35.14 dB (-3rd), -51.36 dB (-7th), -60.69 dB (-11th), -44.71 dB (+5th), -65.05 dB (+9th), and -72.63 dB (+13th), respectively, all suppressed to below -30 dB, thus avoiding interference from these unwanted harmonics to the time modulation array.

[0121] The RF switch is considered to be at 0° phase when it switches to the second and fourth metal phase shift lines. All state transitions are based on this phase difference of 90°, 180°, and 270°. Figures 6-8 To achieve the phase shift effect corresponding to the three phase differences, the 0° state does not need to be drawn.

[0122] like Figure 9The diagram shows a time-modulated array antenna structure composed of a 2-bit time modulation circuit with an integrated air-filled SIW filter. N represents the number of array elements, θ represents the beam pointing angle, and the FPGA acts as a timing control module, providing periodic switching control signals to each integrated filter 2-bit time modulation circuit. The RF signal emitted by the transmitting circuit is split into N paths by a Wilkinson power divider. The FPGA outputs the timing logic signals required for time modulation and provides them to the 2-bit time modulation circuit of the integrated air-filled SIW filter corresponding to each antenna element. After modulation, the signal is radiated into space by the antenna.

[0123] The normalized gain pattern of each harmonic sideband of the time modulation array antenna composed of a 2-bit time modulation circuit without an air-filled SIW filter is shown below. Figure 10 As shown, the horizontal axis θ represents the observation angle of the array pattern in degrees. This indicates that the time-modulated array antenna without an air-filled SIW filter has weak suppression capability for unwanted harmonics and a significant impact on the +1st operating sideband, requiring effective suppression of unwanted harmonics. The normalized gain pattern of the time-modulated array antenna composed of a 2-bit time modulation circuit with an integrated air-filled SIW filter is shown below. Figure 11 As shown, the horizontal axis θ represents the observation angle of the array pattern in degrees. The beam corresponding to the useless harmonics is significantly suppressed, and its gain is more than 30dB lower than the beam gain of the +1 working sideband, effectively avoiding the interference of these useless harmonics on the time modulation array.

[0124] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any modifications or equivalent changes made based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. An integrated air-filled SIW filter 2-bit time modulation circuit, characterized in that, include: The circuit consists of a first-stage time modulation circuit (1), a first coupling window (2), an air-filled SIW filter (3), a second-stage time modulation circuit (4), a second coupling window (5), an input port (6), and an output port (7). The input port (6) is connected to the first-stage time modulation circuit (1). The first-stage time modulation circuit (1) is connected to the first coupling window (2) and then to the air-filled SIW filter (3). The air-filled SIW filter (3) is connected to the second coupling window (5). The second coupling window (5) is connected to the second-stage time modulation circuit (4). The second-stage time modulation circuit (4) is connected to the output port (7). The first-stage time modulation circuit (1) and the second-stage time modulation circuit (4) have the same structure, both including a first metal layer (100), a first dielectric substrate (200) and a second metal layer (300). The first dielectric substrate (200) is disposed on the lower surface of the first metal layer (100), and the second metal layer (300) is disposed on the lower surface of the first dielectric substrate (200). The air-filled SIW filter (3) includes a third metal layer (400), a second dielectric substrate (500), a fourth metal layer (600), a fifth metal layer (700), a third dielectric substrate (800), and a sixth metal layer (900). The third metal layer (400) is disposed on the lower surface of the second metal layer (300), the second dielectric substrate (500) is disposed on the lower surface of the third metal layer (400), the fourth metal layer (600) is disposed on the lower surface of the second dielectric substrate (500), the fifth metal layer (700) is disposed on the lower surface of the fourth metal layer (600), the third dielectric substrate (800) is disposed on the lower surface of the fifth metal layer (700), and the sixth metal layer (900) is disposed on the lower surface of the third dielectric substrate (800). The first coupling window (2) and the second coupling window (5) are disposed on the second metal layer (300).

2. The integrated air-filled SIW filter 2-bit time modulation circuit according to claim 1, wherein, The first metal layer (100) includes a metal sheet (101), a power supply port (104), a metal pad (105), a first metal phase shift line (106), a second metal phase shift line (107), a third metal phase shift line (110), a fourth metal phase shift line (111), a metal coupling line (108), and an RF single-pole double-throw switch (109). The spacing between the metal sheet (101), the power supply port (104), the metal pad (105), the first metal phase shift line (106), the second metal phase shift line (107), the third metal phase shift line (110), the fourth metal phase shift line (111), and the metal coupling line (108) is formed by slots; The six pins of the radio frequency single-pole double-throw switch (109) are each connected to a metal pad (105). The radio frequency single-pole double-throw switch (109) periodically switches the direction path to the first metal phase shift line (106), the second metal phase shift line (107), the third metal phase shift line (110), and the fourth metal phase shift line (111) to achieve the filtering phase shifting functions of 0°, 90°, 180°, and 270°. The metal sheet (101) is provided with a large metal via (103) and a small metallized via (102).

3. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 2, characterized in that, The first dielectric substrate (200) is provided with a first dielectric through-hole (201), a second dielectric through-hole (202), a third dielectric through-hole (203), a fourth dielectric through-hole (204) and a fifth dielectric through-hole (205). The first dielectric via (201) is a metallized via, which is arrayed in the edge region of the filter structure to realize the electrical interconnection between the first metal layer (100) and the second metal layer (300); The second medium through hole (202) is a non-metallic through hole used to fix the SMA connector; The third dielectric via (203) is a metallized via used to realize the connection between the first metal phase shift line (106), the third metal phase shift line (110) and the second metal layer (300); The fourth dielectric via (204) is a metallized via used to realize the connection between the metal pad (105) in the first metal layer (100) and the second metal layer (300); The fifth dielectric via (205) is a non-metallized via used to achieve mechanical fixation of the filter.

4. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 3, characterized in that, The second metal layer (300) is provided with a first mounting through hole (301), a second mounting through hole (302), a third coupling window (303) and a third mounting through hole (304). The first mounting via (301) is a metallized via, corresponding to the position of the first dielectric via (201) on the first dielectric substrate (200); The second mounting through hole (302) is used to fix the SMA connector; The third coupling window (303) is symmetrical about the midline of the long side of the second metal layer (300) to realize electromagnetic coupling between the upper feed network and the lower SIW resonant cavity; The third mounting through hole (304) is a non-metallized through hole, and the position of the third mounting through hole (304) corresponds to the position of the fifth dielectric through hole (205) of the first dielectric substrate (200) to achieve mechanical fixation of the filter.

5. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 4, characterized in that, The third metal layer (400) is provided with a first fixing through hole (401), a second fixing through hole (402), a third fixing through hole (403), and a first square air cavity (404). The first fixed through hole (401) is a metallized through hole, which is periodically arranged around the air resonant cavity; The second fixing through hole (402) corresponds to the third mounting through hole (304) of the second metal layer (300) to achieve mechanical fixation of the filter; The third fixing through hole (403) is used to fix the SMA connector; The first square air cavity (404) achieves electromagnetic coupling through the central coupling gap of the third metal layer (400).

6. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 3, characterized in that, The second dielectric substrate (500) is provided with a first substrate through hole (501), a second substrate through hole (502), a third substrate through hole (503) and a second square air cavity (504). The first substrate via (501) is a metallized via, which is periodically arranged around the air resonant cavity to form a closed metal cavity; The second substrate via (502) is a non-metallized via, which corresponds to the position of the third mounting via (304) of the second metal layer (300) to achieve mechanical fixation of the filter; The third substrate through-hole (503) is used to fix the SMA connector; The second square air cavity (504) achieves electromagnetic coupling through the central coupling gap of the second dielectric substrate (500).

7. The 2-bit time modulation circuit for an integrated air-filled SIW filter according to claim 3, characterized in that, The fourth metal layer (600) is provided with a first metal through hole (601), a second metal through hole (602), a third metal through hole (603) and a third shaped air cavity (604). The first metal via (601) is a metallized via, arranged periodically around the air resonant cavity; The second metal through hole (602) corresponds to the third mounting through hole (304) of the second metal layer (300) to achieve mechanical fixation of the filter; The third metal through hole (603) is used to fix the SMA connector; The third-dimensional air cavity (604) achieves electromagnetic coupling through the central coupling gap of the fourth metal layer (600).

8. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 3, characterized in that, The fifth metal layer (700), the third dielectric substrate (800), and the sixth metal layer (900) are provided with a first metal layer through hole (701), a first through hole (801), and a first flange through hole (901) at corresponding positions. The first metal layer through hole (701), the first through hole (801), and the first flange through hole (901) are non-metallized through holes, and correspond to the position of the second metal through hole (602) of the fourth metal layer (600) to achieve mechanical fixation of the filter; The fifth metal layer (700), the third dielectric substrate (800), and the sixth metal layer (900) are provided with a second metal layer through hole (702), a second through hole (802), and a second flange through hole (902) at corresponding positions. The second metal layer through hole (702), the second through hole (802), and the second flange through hole (902) are non-metallic through holes used to fix the SMA connector.

9. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 1, characterized in that, The first-stage time modulation circuit (1) and the second-stage time modulation circuit (4) are provided with periodic control signals by the same timing control module.

10. The 2-bit time modulation circuit of an integrated air-filled SIW filter according to claim 1, characterized in that, The center frequency of the air-filled SIW filter (3) is consistent with the target operating sideband frequency of the first-stage time modulation circuit (1) and the second-stage time modulation circuit (4), and the passband width of the air-filled SIW filter (3) is smaller than the frequency interval between adjacent non-operating harmonic sidebands.

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