A microstrip circuit and radio frequency coding device based on multi-modal radio frequency coding
By introducing a multimode radio frequency coding scheme into the microstrip circuit, and utilizing an L-shaped bending structure and a mode selection switch, the dispersion problem of the microstrip circuit in broadband applications is solved, thereby improving the performance of the communication system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HOHAI UNIV
- Filing Date
- 2026-05-09
- Publication Date
- 2026-06-09
AI Technical Summary
Existing radio frequency coded microstrip circuits suffer from dispersion effects in broadband applications, which severely degrades the phase consistency of quadrature and in-phase modes, affecting communication performance.
A multi-mode radio frequency coding scheme is adopted. By setting the terminal short line of the positive mode microstrip line as an L-shaped bend structure, and combining the absorption mode microstrip line, positive mode and negative mode microstrip line, the mode selection switch is used for coding to reduce dispersion effect and improve broadband performance.
It effectively reduces the dispersion effect of microstrip circuits in a wide bandwidth, improving the broadband performance of communication systems and the accuracy of signal processing.
Smart Images
Figure CN224342500U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of microstrip circuit technology, and in particular to a microstrip circuit and radio frequency coding device based on multimode radio frequency coding. Background Technology
[0002] In wireless communication, data transmission and reception require encryption to ensure security. Traditional digital encryption techniques involve down-converting and analog-to-digital converting the received electromagnetic signal, followed by complex parameter extraction, waveform reconstruction, and modal analysis in the digital domain, and finally outputting the signal via digital-to-analog conversion and up-conversion. However, the digital operations and analog-to-digital conversion introduce significant physical delays, limiting communication speed.
[0003] In order to overcome the response bottleneck caused by digital processing, the industry has begun to explore radio frequency coding schemes that perform signal processing directly at the radio frequency physical layer. By directly using microwave switch arrays and microstrip line phase shifting circuits to reconstruct the mode of the incoming radio frequency wave, the physical delay introduced by digital operation and analog-to-digital conversion can be eliminated, thereby improving communication performance.
[0004] However, since the effective dielectric constant of the microstrip line varies with frequency, the phase shift of the microstrip line phase shifting unit exhibits nonlinear drift within the operating frequency band, resulting in a severe deterioration in the orthogonality accuracy and phase consistency of the in-phase mode (1) and the quadrature mode (j) (dispersion effect). This dispersion effect is particularly prominent in wideband applications, leading to insufficient broadband performance of RF-coded microstrip circuits in the prior art. Utility Model Content
[0005] Therefore, the purpose of this invention is to provide a microstrip circuit and a radio frequency coding device based on multimodal radio frequency coding, so as to solve the problem of insufficient broadband performance of radio frequency coding microstrip circuits in the prior art.
[0006] This utility model provides a microstrip circuit based on multimodal radio frequency coding, comprising:
[0007] The phase-shifting encoding unit includes an input microstrip line and an output microstrip line arranged in parallel and mirror-symmetrical configuration, as well as an absorption mode microstrip line, a positive mode microstrip line, and a negative mode microstrip line respectively connected between the input microstrip line and the output microstrip line. Mode selection switches are provided in the corresponding paths of the absorption mode microstrip line, the positive mode microstrip line, and the negative mode microstrip line. Two sets of phase-shifting encoding units are arranged in parallel and spaced apart.
[0008] The quadrature power divider has two phase output terminals connected to the input microstrip lines of the two sets of phase-shifting encoding units respectively via a first in-phase mode microstrip line and a first quadrature mode microstrip line.
[0009] The combiner has two phase input terminals connected to the output microstrip lines of the two sets of phase-shifting coding units respectively via a second in-phase mode output microstrip line and a second quadrature mode output microstrip line.
[0010] The positive mode microstrip line is a straight-through microstrip line, and a terminal shorting line is connected to the straight-through microstrip line. The terminal shorting line is provided with two segments at intervals and has an L-shaped bending structure. The two bending segments of the L-shaped bending structure are parallel to the positive mode microstrip line and have opposite directions.
[0011] Optionally, the first in-phase mode microstrip line is L-shaped and connected with a terminal short-circuit stable phase stub. The terminal short-circuit stable phase stub is provided with two segments at intervals and is perpendicular to the first in-phase mode microstrip line.
[0012] Optionally, the absorption mode microstrip line includes two sets of microstrip absorption structures, which are respectively connected to the midpoints of the input microstrip line and the output microstrip line and are arranged symmetrically.
[0013] The microstrip absorption structure includes a linear transmission section and a grounding section disposed at the end of the linear transmission section. A first switch and an impedance matching resistor are connected sequentially between the linear transmission section and the grounding section. A first microstrip tuning stub is also disposed on the output side of the first switch. The first microstrip tuning stub is perpendicular to the linear transmission section.
[0014] Optionally, the positive-mode microstrip line and the negative-mode microstrip line are respectively connected to both ends of the input microstrip line;
[0015] The input microstrip line is further connected in series with a second switch and a third switch. The second switch is located in the two arms of the input microstrip line, and the third switch is located at both ends of the input microstrip line. The third switch is connected to the positive mode microstrip line and the negative mode microstrip line respectively.
[0016] The output side of the second switch is provided with a second microstrip tuning stub, and the output side of the third switch is provided with a third microstrip tuning stub.
[0017] Optionally, the second microstrip tuning stub is L-shaped, with its first segment perpendicular to the input microstrip line and its tail segment parallel to the input microstrip line, the tail end of the second microstrip tuning stub pointing towards the near end of the input microstrip line.
[0018] Optionally, the third microstrip tuning stub is linear and parallel to the input microstrip line.
[0019] Optionally, a passive inverter is provided in the negative mode microstrip line.
[0020] Optionally, both the quadrature power divider and the combiner include Wilkinson power dividers.
[0021] Optionally, the transmission section of the Wilkinson power divider is arc-shaped.
[0022] Another aspect of this invention provides a radio frequency coding device based on multimode radio frequency coding, including the microstrip circuit based on multimode radio frequency coding described above.
[0023] This invention provides a microstrip circuit based on multimode radio frequency coding, comprising a phase-shifting coding unit connected between a quadrature power divider and a combiner. The quadrature power divider divides the input signal into in-phase and quadrature modes, outputting them to two sets of phase-shifting coding units. The phase-shifting coding units further perform mode coding using absorption mode microstrip lines, positive mode microstrip lines, and negative mode microstrip lines, and select the desired coded mode using a mode selection switch. The encoded in-phase and quadrature modes are then combined by the combiner using space vector synthesis to obtain the final coded signal. The positive mode microstrip line is a straight-through microstrip line, with its output phase synchronized with the input phase. A terminating short circuit is also connected to the straight-through microstrip line, with two L-shaped bends spaced apart. The bends of the two L-shaped bends are parallel to the positive mode microstrip line and face opposite directions. This invention effectively reduces the dispersion effect of the straight-through microstrip line in a wide bandwidth and improves its broadband performance by setting terminating short circuits on the straight-through microstrip line of the positive mode microstrip line. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the module structure of the radio frequency coding device based on multimodal radio frequency coding in an embodiment of this utility model;
[0025] Figure 2 This is a schematic diagram of the microstrip structure of the microstrip circuit based on multimode radio frequency coding in an embodiment of this utility model;
[0026] Figure 3 This is a schematic diagram of the microstrip structure of the phase-shifting coding unit of the microstrip circuit based on multi-mode radio frequency coding in an embodiment of this utility model;
[0027] Figure 4 The phase difference test results between the j and -j coded modes in the orthogonal branch of the microstrip circuit based on multimode radio frequency coding in this embodiment of the present invention;
[0028] Figure 5 The phase difference test results between the 1 and -1 coded modes in the in-phase branch of the microstrip circuit based on multimode radio frequency coding in this embodiment of the present invention;
[0029] Figure 6The phase difference test results between the -j and -1 coded modes of the microstrip circuit based on multimode radio frequency coding in this embodiment of the present invention are shown.
[0030] Figure 7 The phase difference test results between the j and 1 coded modes of the microstrip circuit based on multimode radio frequency coding in this embodiment of the present invention;
[0031] Figure 8 The reflection coefficient test results of some coded modes of the microstrip circuit based on multimode radio frequency coding in the embodiments of this utility model are shown.
[0032] Figure 9 The insertion loss test results are for some coded modes of the microstrip circuit based on multimode radio frequency coding in the embodiments of this utility model.
[0033] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this utility model. Detailed Implementation
[0034] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete.
[0035] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.
[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0037] To address the insufficient broadband performance of existing radio frequency (RF) encoded microstrip circuits, this invention provides a microstrip circuit based on multimode RF encoding. The circuit includes a phase-shifting encoding unit connected between a quadrature power divider and a combiner. The quadrature power divider divides the input signal into in-phase and quadrature modes, outputting them to two sets of phase-shifting encoding units. The phase-shifting encoding units further encode the signal using absorption mode microstrip lines, positive mode microstrip lines, and negative mode microstrip lines. A mode selection switch selects the desired encoding mode. The encoded in-phase and quadrature modes are then combined using a space vector synthesizer to obtain the final encoded signal. The positive mode microstrip line is a straight-through microstrip line with output phase synchronized with input phase. A terminating short-circuit line is connected to the straight-through microstrip line, with two L-shaped bends spaced apart. The bends of the two L-shaped bends are parallel to the positive mode microstrip line but face opposite directions. By setting a termination short circuit on the through microstrip line of the positive mode microstrip line, the dispersion effect of the through microstrip line in the broadband can be effectively reduced, thereby improving broadband performance.
[0038] Specifically, such as Figure 1 The diagram shown illustrates the module structure of the radio frequency coding device based on multimode radio frequency coding in this embodiment. The input signal f I (t) is divided into in-phase mode (represented by 1 or I, with phase synchronized with the input signal) and quadrature mode (usually represented by j or Q, with phase 90° out of phase with the input signal) by the quadrature power divider 21. Then, it is further phase-shifted and encoded by two sets of phase-shifting encoding units in the mode encoding circuit 30. Finally, it is synthesized by the combiner 22 to obtain the output signal fo(t). The encoding mode selection of the phase-shifting encoding unit is controlled by the encoding controller 10. The encoding controller 10 can be implemented by FPGA (Field Programmable Gate Array).
[0039] The composition expression for the output signal fo(t) is: cos(ωt-a)+cos(ωt+b)= cos(ωt+c), the modal expression is ±1±j, where cos(ωt-a) is the signal expression of the in-phase branch, and cos(ωt+b) is the signal expression of the quadrature branch. cos(ωt+c) is the expression for the output signal fo(t), ±1 represents the mode of the in-phase branch, a represents the phase of the in-phase mode in vector space, ±j represents the mode of the quadrature mode, b represents the phase of the quadrature mode in vector space, c represents the phase of the output mode in vector space, ω represents the frequency of the transmitted signal, and the amplitude of the synthesized signal is the reference value of each of the two branch signals. times.
[0040] In the phase-shifting coding unit, the phase shift of the 1-coded mode is 0°; the 0-coded mode is in an open-circuit state, the signal is grounded, completely absorbed, and there is no effective signal output; the phase shift of the -1-coded mode is 180°. Taking the 1+j mode coding as an example, both sets of phase-shifting coding units select the 1-coded mode, and the synthesis expression is: cos(ωt+0)+cos(ωt+90)= cos(ωt+45), the output signal has an angle of 45° in the vector space. By selecting the encoding mode, the phase shift angle of the output signal can include 45°, 135°, 225°, and 315°, thus achieving complete encoding.
[0041] Please refer to further details. Figure 2 and Figure 3 The diagram shown is a schematic diagram of the microstrip structure of the microstrip circuit in this embodiment.
[0042] The phase-shifting encoding unit includes an input microstrip line 31 and an output microstrip line 32 arranged in parallel and mirror-symmetrical configuration, as well as an absorption mode microstrip line (0-coded mode), a positive mode microstrip line (1-coded mode), and a negative mode microstrip line (-1-coded mode) connected between the input microstrip line 31 and the output microstrip line 32, respectively. Mode selection switches 12 are provided in the corresponding paths of the absorption mode microstrip line, the positive mode microstrip line, and the negative mode microstrip line. Two sets of phase-shifting encoding units are arranged in parallel and spaced apart, respectively used for encoding phase shifting of quadrature modes and in-phase modes.
[0043] The two-phase output terminals of the quadrature power divider 21 are respectively connected to the input microstrip lines 31 of the two sets of phase-shifting encoding units through the first in-phase mode microstrip line 211 and the first quadrature mode microstrip line 212; the two-phase input terminals of the combiner 22 are respectively connected to the output microstrip lines 32 of the two sets of phase-shifting encoding units through the second in-phase mode output microstrip line 221 and the second quadrature mode output microstrip line 222.
[0044] Each microstrip line is disposed on the front side of the substrate 100. The mode selection switch 12 and the driving end impedance unit 121 (copper layer, with an area larger than the microstrip line size, providing low impedance characteristics and reducing electromagnetic interference caused by high-frequency driving signals) are also disposed on the front side of the substrate 100. Multiple connectors 110 are also fixedly disposed on the substrate 100 for signal input, output, and driving signal transmission of each mode selection switch 12. The driving signal lines 11 of the mode selection switches 12 (including multiple switches with a symmetrical design; in this embodiment, only some switches are described as examples, and other symmetrical parts are not described in detail) are disposed on the back side of the substrate 100 and connected to the corresponding driving end impedance unit 121 on the front side through the through holes in the substrate 100. The back side of the substrate 100 is used to set the equivalent ground, and the part on the front side that needs to be grounded passes through the substrate 100 and is connected to the equivalent ground on the back side.
[0045] The positive mode microstrip line includes a through microstrip line 321. The length of the through microstrip line 321 is an integer multiple of the full wavelength of the center frequency of the design bandwidth (unless otherwise specified, the center frequency in this article refers to the center frequency of the design bandwidth). The phase delay and lead problems of the dispersion effect will accumulate. In order to reduce the dispersion effect of the positive mode microstrip line, a terminating short line 322 is also connected to the through microstrip line 321. The terminating short line 322 is provided with two segments at intervals and has an L-shaped bending structure (the total length is one-quarter of the center frequency). The bending segments of the two L-shaped bending structures are parallel to the through microstrip line 321 and face opposite directions. The end of the terminating short line 322 is grounded.
[0046] When the frequency of the transmitted signal is lower than the center frequency, the wavelength of the transmitted signal increases and the phase leads. At this time, the inductive characteristic of the terminal shorting line 322 is enhanced, which delays the phase of the transmitted signal and moves it closer to the standard phase of the center frequency, reducing phase shift and dispersion. When the frequency of the transmitted signal is higher than the center frequency, the wavelength of the transmitted signal shortens and the phase lags. At this time, the capacitive characteristic of the terminal shorting line 322 is enhanced, which leads the phase of the transmitted signal and moves it closer to the standard phase of the center frequency, reducing phase shift and dispersion.
[0047] To further reduce the impact of dispersion, in this embodiment, the first in-phase mode microstrip line 211 is L-shaped and connected to a terminal short-circuit stable phase stub 201. The terminal short-circuit stable phase stub 201 is provided with two segments spaced apart and perpendicular to the first in-phase mode microstrip line 211. The end of the terminal short-circuit stable phase stub 201 is grounded, and the length of a single stub is one-quarter of the wavelength of the center frequency.
[0048] In radio frequency systems, the corners of physically bent structures are usually chamfered to reduce tip radiation. Without compromising the core parameter requirements of radio frequency transmission on the physical structure, the chamfer can be designed according to actual needs, and this application does not impose any special restrictions on it.
[0049] The absorbing mode microstrip line includes two sets of microstrip absorption structures. The two sets of microstrip absorption structures are connected to the midpoints of the input microstrip line and the output microstrip line, respectively, and are symmetrically arranged. Thus, they are positioned in the middle of the phase-shifting encoding unit. Compared with the positive mode microstrip lines and negative mode microstrip lines on both sides, the transmitted signals that can be received first are preferentially absorbed by the ground.
[0050] Specifically, the microstrip absorption structure includes a linear transmission section 311 and a grounding section 312 disposed at the end of the linear transmission section 311. The size of the grounding section 312 is larger than that of the linear transmission section 311 to ensure grounding efficiency. A first switch Q1 and an impedance matching resistor 313 (usually 50Ω, which can be adjusted according to the specific matching impedance of the actual RF system) are connected sequentially between the linear transmission section 311 and the grounding section 312. A first microstrip tuning stub 301 is also disposed on the output side of the first switch Q1. The first microstrip tuning stub 301 is perpendicular to the linear transmission section 311.
[0051] To improve the isolation between the positive-mode microstrip line and the negative-mode microstrip line relative to the absorbing-mode microstrip line and reduce coupling interference, in this embodiment, the positive-mode microstrip line and the negative-mode microstrip line are respectively connected to both ends of the input microstrip line and are disposed in the space on both sides of the absorbing-mode microstrip line.
[0052] Furthermore, a second switch Q2 and a third switch Q3 are connected in series in the input microstrip line 31. The second switch Q2 is located in the two arms of the input microstrip line 31, and the third switch Q3 is located at both ends of the input microstrip line 31, and is connected to the positive mode microstrip line and the negative mode microstrip line respectively through the third switch Q3. A second microstrip tuning stub 302 is provided on the output side of the second switch Q2, and a third microstrip tuning stub 303 is provided on the output side of the third switch Q3. Among them, for the microstrip tuning stubs located on the output microstrip line 32, the output side of the corresponding switch is the side closer to the corresponding positive mode microstrip line or negative mode microstrip line. That is, each microstrip tuning stub is isolated from the external first in-phase mode microstrip line 211, first quadrature mode microstrip line 212, second in-phase mode output microstrip line 221, and second quadrature mode output microstrip line 222 through the switch, so as to reduce the reflection coefficient when the switch is turned on and increase the reflection coefficient when the switch is turned off. The ends of each microstrip tuning stub are round dots and are in an open circuit state.
[0053] Each switch and microstrip tuning stub is relatively mirror-symmetrical on the positive mode microstrip line side and the negative mode microstrip line side, and is also relatively mirror-symmetrical on the input microstrip line 31 side and the output microstrip line 32 side. The specific structure of these components will not be described in detail in this application.
[0054] Due to space constraints, to reduce the coupling effect between the microstrip tuning stub and other components, in this embodiment, the second microstrip tuning stub 302 is L-shaped, with its first segment perpendicular to the input microstrip line 31 and its tail segment parallel to the input microstrip line 31. The tail end of the second microstrip tuning stub 302 points towards the near end of the input microstrip line 31, extending outward away from the absorption mode microstrip line to increase the physical distance from the absorption mode microstrip line and reduce the electromagnetic coupling effect. The third microstrip tuning stub 303 is linear and parallel to the input microstrip line 31.
[0055] To achieve a 180° phase shift in negative mode coding, in this embodiment, a passive inverter 332 is provided in the negative mode microstrip line, and the passive inverter 332 is connected to the outside through the negative mode transmission microstrip line 331.
[0056] In this embodiment, both the quadrature power divider 21 and the combiner 22 include Wilkinson power dividers, and the two Wilkinson power dividers are structurally symmetrical. The transmission section of the Wilkinson power divider is arc-shaped.
[0057] In a specific example, with a design bandwidth in the range of 14GHz to 14.5GHz, its performance testing is as follows: Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown, the phase difference error between the orthogonal positive coding mode j and the orthogonal negative coding mode -j is within the range of 180°±1.6°, the phase difference error between the in-phase positive coding mode 1 and the in-phase negative coding mode -1 is within the range of 180°±1.6°, the phase difference error between the orthogonal negative coding mode -j and the in-phase negative coding module -1 is within the range of 90°±5.5°, and the phase difference error between the orthogonal positive coding mode j and the in-phase positive coding module 1 is within the range of 90°±5.5°. These are within the allowable error range and can meet the actual usage requirements.
[0058] Figure 8 and Figure 9 The test results for the reflection coefficient and insertion loss of some coded modes are shown respectively, as follows: Figure 8 and Figure 9 As shown, the reflection coefficients (RL, which is the logarithm of the reciprocal of the magnitude of the reflection coefficient, in dB) of the orthogonal positive coding mode j, orthogonal negative coding mode -j, in-phase positive coding module 1, and in-phase negative coding module -1 are all less than -15dB and within the bandwidth, with a difference within -3dB. The reflection is low and the consistency is good. The insertion loss is within 13dB, which is within the 8~15dB reference range of passive encoders and can meet the usage requirements.
[0059] This utility model also provides a radio frequency coding device based on multimode radio frequency coding, including the microstrip circuit based on multimode radio frequency coding described above.
[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0061] The above-described embodiments are merely illustrative of several specific implementations of this utility model, and while the descriptions are detailed, they should not be construed as limiting the scope of protection of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the scope of protection of this utility model. Therefore, the scope of protection of this utility model should be determined by the appended claims.
Claims
1. A microstrip circuit based on multimode radio frequency coding, characterized in that, include: The phase-shifting encoding unit includes an input microstrip line and an output microstrip line arranged in parallel and mirror-symmetrical configuration, as well as an absorption mode microstrip line, a positive mode microstrip line, and a negative mode microstrip line respectively connected between the input microstrip line and the output microstrip line. Mode selection switches are provided in the corresponding paths of the absorption mode microstrip line, the positive mode microstrip line, and the negative mode microstrip line. Two sets of phase-shifting encoding units are arranged in parallel and spaced apart. The quadrature power divider has two phase output terminals connected to the input microstrip lines of the two sets of phase-shifting encoding units respectively via a first in-phase mode microstrip line and a first quadrature mode microstrip line. The combiner has two phase input terminals connected to the output microstrip lines of the two sets of phase-shifting coding units respectively via a second in-phase mode output microstrip line and a second quadrature mode output microstrip line. The positive mode microstrip line is a straight-through microstrip line, and a terminal shorting line is connected to the straight-through microstrip line. The terminal shorting line is provided with two segments at intervals and has an L-shaped bending structure. The two bending segments of the L-shaped bending structure are parallel to the positive mode microstrip line and have opposite directions.
2. The microstrip circuit based on multimode radio frequency coding according to claim 1, characterized in that, The first in-phase mode microstrip line is L-shaped and connected with a terminal short-circuit stable phase stub. The terminal short-circuit stable phase stub is provided with two segments at intervals and is perpendicular to the first in-phase mode microstrip line.
3. The microstrip circuit based on multimode radio frequency coding according to claim 1, characterized in that, The absorption mode microstrip line includes two sets of microstrip absorption structures, which are respectively connected to the midpoints of the input microstrip line and the output microstrip line and are arranged symmetrically. The microstrip absorption structure includes a linear transmission section and a grounding section disposed at the end of the linear transmission section. A first switch and an impedance matching resistor are connected sequentially between the linear transmission section and the grounding section. A first microstrip tuning stub is also disposed on the output side of the first switch. The first microstrip tuning stub is perpendicular to the linear transmission section.
4. The microstrip circuit based on multimode radio frequency coding according to claim 1, characterized in that, The positive-mode microstrip line and the negative-mode microstrip line are respectively connected to both ends of the input microstrip line; The input microstrip line is further connected in series with a second switch and a third switch. The second switch is located in the two arms of the input microstrip line, and the third switch is located at both ends of the input microstrip line. The third switch is connected to the positive mode microstrip line and the negative mode microstrip line respectively. The output side of the second switch is provided with a second microstrip tuning stub, and the output side of the third switch is provided with a third microstrip tuning stub.
5. The microstrip circuit based on multimodal radio frequency coding according to claim 4, characterized in that, The second microstrip tuning stub is L-shaped, with its first segment perpendicular to the input microstrip line and its tail segment parallel to the input microstrip line. The tail end of the second microstrip tuning stub points towards the near end of the input microstrip line.
6. The microstrip circuit based on multimode radio frequency coding according to claim 4, characterized in that, The third microstrip tuning stub is linear and parallel to the input microstrip line.
7. The microstrip circuit based on multimode radio frequency coding according to claim 1, characterized in that, A passive inverter is provided in the negative mode microstrip line.
8. The microstrip circuit based on multimode radio frequency coding according to claim 1, characterized in that, Both the orthogonal power divider and the combiner include Wilkinson power dividers.
9. The microstrip circuit based on multimode radio frequency coding according to claim 8, characterized in that, The transmission section of the Wilkinson power divider is arc-shaped.
10. A radio frequency coding device based on multimodal radio frequency coding, characterized in that, Includes the microstrip circuit based on multimodal radio frequency coding as described in any one of claims 1 to 9.