A miniaturized broadband TEM antenna with dual linear and circular polarization modes

Abstract

The present invention discloses a miniaturized broadband TEM antenna with dual linear polarization, dual circular polarization, and multiple modes. The antenna includes dual linear polarization modes and dual circular polarization modes, and the selection of the dual linear polarization mode and the dual circular polarization mode is achieved by controlling the feeding amplitude and phase difference of multiple ports. Quasi-TEM waves are generated by a metal stepped horn antenna and a planar multilayer feeding structure. A cross-slot structure and a multilayer substrate integrated waveguide (SIW) feeder are used to achieve independent dual linear polarization and dual right-handed / left-handed circular polarization multiple modes, effectively reducing the antenna size. Both the linear and circular polarization operating modes of the TEM antenna have a broadband return loss (less than 10 dB) and a high gain of 8.2-10.9 dBi within the operating range of 18-19.5 GHz. When operating as a circularly polarized antenna, the antenna axial ratio (AR) is less than 3 dB within this frequency range.

Description

Technical Field

[0001] The invention belongs to the technical field of antenna design, and in particular to a miniaturized broadband TEM antenna with dual linear polarization, dual circular polarization and multiple modes. Background Art

[0002] With the development of modern wireless communication systems, in addition to increasing requirements for antenna performance characteristics such as frequency band performance, size, and gain, antennas are also required to have multi-mode and multi-functional characteristics. Antennas with selectable multi-polarization modes can enhance the flexibility and multi-scenario capabilities of communication systems.

[0003] Due to the advantages of its horn structure, TEM antennas can provide superior performance such as high gain, wide bandwidth, simple structure, low dispersion, low distortion and high power handling capability. They are used in ultra-wideband systems, high-power microwave (HPM), electromagnetic compatibility (EMC) measurement and ground penetrating radar.

[0004] However, the large size of traditional TEM antennas significantly limits their use cases. Consequently, miniaturization of TEM antennas has attracted increasing attention in recent years. Using ridged waveguide structures or stepped horn structures can reduce the size of TEM antennas while maintaining a wide bandwidth.

[0005] Due to the demand for more polarization modes and miniaturization, there are some dual-polarized TEM antenna designs (1. JACazden, MA Elmansouri and DS Filipovic, "Wideband Miniaturized Dual-Polarized TEM Horn," 2020 IEEE International Symposium on Antennas andPropagation and North American Radio Science Meeting, Montreal, QC, Canada,2020, pp. 483-484, doi: 10.1109 / IEEECONF35879.2020.9330305.) and circularly polarized TEM antenna array designs (2. G. Strauss and K. Breitsameter, "A circular polarized tem hornantenna array with large scanning angle," 2011 IEEE Radio and WirelessSymposium, Phoenix, AZ, USA, 2011, pp. 98-101, doi: 10.1109 / RWS.2011.5725477.3. MA Elmansouri, J. Ha and DS Filipovic, "Ultrawideband TEM HornCircular Array," in IEEE Transactions on Antennas and Propagation, vol. 65, no. 3, pp. 1374-1379, March 2017, doi: 10.1109 / TAP.2016.2637871.) have been published successively. The design principle of a dual-linearly polarized TEM antenna is to generate orthogonal dual-linear polarization waves through mutually perpendicular horn structures. Circularly polarized TEM antennas are realized through circularly polarized TEM arrays.

[0006] However, existing antennas can only achieve a certain polarization mode, which is not very flexible and difficult to adapt to the rapid development of modern communication equipment. Therefore, research on multi-mode antennas will have strong market competitiveness and development prospects. Summary of the Invention

[0007] The present invention aims to address the problems of the prior art by providing a miniaturized, broadband TEM antenna with dual linear and circular polarization modes. This antenna incorporates a cross-shaped slot structure, combined with multi-layer planar SIW feed lines and mutually perpendicular metal horns, to generate mutually perpendicular dual linearly polarized TEM waves. By combining these mutually perpendicular dual linearly polarized TEM waves with a ±90-degree phase shift, dual left-handed and right-handed circularly polarized waves are achieved.

[0008] The technical solution for achieving the objectives of the present invention is: a miniaturized broadband TEM antenna with dual linear polarization, dual circular polarization and multi-mode, which includes dual linear polarization mode and dual circular polarization mode, and realizes mode switching selection through multi-port control; specifically: the antenna realizes the selection of dual linear polarization mode and dual circular polarization mode by controlling the feeding amplitude and phase difference of multiple ports.

[0009] Furthermore, the multi-port includes two mutually perpendicular ports 1 and 2;

[0010] When the dual linear polarization mode is implemented: when the port 1 is fed alone, the TEM antenna implements radiation in a linear polarization mode with the electric field direction along a first direction; when the port 2 is fed alone, the TEM antenna implements radiation in a linear polarization mode with the electric field direction along a second direction; the first direction and the second direction are perpendicular to each other;

[0011] When the dual circular polarization mode is implemented: when port 1 and port 2 are fed simultaneously and port 1 leads port 2 with a phase difference of 90 degrees, the TEM antenna realizes right-hand circular polarization mode radiation; when port 1 and port 2 are fed simultaneously and port 2 leads port 1 with a phase difference of 90 degrees, the TEM antenna realizes left-hand circular polarization mode radiation.

[0012] Furthermore, the antenna includes a metal horn portion and a SIW feeding portion, the SIW feeding portion including an upper SIW feeding structure and a lower SIW feeding structure arranged sequentially from top to bottom, a first SIW port being provided in the upper SIW feeding structure as the port 1, a second SIW port being provided in the lower SIW feeding structure as the port 2, a cross-shaped slot structure being provided on the metal layer at the connection between the metal horn portion and the upper SIW feeding structure, and the two sides of the "cross" are respectively along the first direction and the second direction, and are used for feeding port 2 and port 1, respectively; a straight-line rectangular slot structure is provided on the metal layer at the connection between the upper SIW feeding structure and the lower SIW feeding structure, the straight-line rectangular slot structure being provided along the first direction and being located directly below the slot along the first direction in the cross-shaped slot structure.

[0013] Furthermore, the lengths of the cross-shaped slot structure and the straight rectangular slot structure do not exceed the range of the metal horn portion.

[0014] Furthermore, the structural parameters of the slots along the first direction in the cross-shaped slot structure are the same as the structural parameters of the straight rectangular slots.

[0015] Furthermore, the upper SIW feed structure includes a first metal layer, a first dielectric layer, and a second metal layer arranged in sequence from top to bottom, and the lower SIW feed structure includes a second metal layer, a second dielectric layer, and a third metal layer arranged in sequence from top to bottom; the cross-shaped slot structure is arranged on the first metal layer, and the straight rectangular slot structure is arranged on the second metal layer.

[0016] Furthermore, the metal speaker portion has a stepped structure.

[0017] Furthermore, the metal horn part includes four stepped rectangular metal blocks, each of which is narrow at the top and wide at the bottom; the four stepped rectangular metal blocks are respectively located in the four quadrants formed by the cross-shaped gap structure and are connected at the bottom, and two of the stepped rectangular metal blocks constitute a horn structure.

[0018] Furthermore, the four stepped rectangular metal blocks are symmetrically arranged about the center of the cross-shaped gap structure.

[0019] Furthermore, both SIW ports are matched with an externally connected 50Ω coaxial cable structure through a conversion structure of SIW layers and microstrips.

[0020] Compared with the prior art, the present invention has the following significant advantages:

[0021] (1) For the first time, a multi-mode TEM antenna was innovatively proposed. By controlling two ports through a digital system, it can generate selective dual-linear polarization / dual-circular polarization waves (the antenna introduces a cross-slot structure, combines a multi-layer planar SIW feeder and a mutually perpendicular metal horn structure, and can generate mutually perpendicular dual-linear polarization TEM waves; by combining mutually perpendicular dual-linear polarization TEM waves with a ±90-degree phase difference, dual left-handed / right-handed circularly polarized waves are achieved). It has extremely low latency and is very suitable for application in multi-functional and multi-scenario modern communication systems.

[0022] (2) When the dual linear polarization mode is realized, feeding port 1 or port 2 alone will stimulate linear polarization radiation. Since the vertical structure at the port feeding connection, the stepped rectangular metal horn structure divided into four parts, and the cross-shaped slot structure in the gap of the metal horn structure all have the characteristics of vertical multi-mode structure along the X-axis and along the Y-axis, there is a high degree of isolation between the two ports, which will avoid mutual influence between the two ports when the linear polarization mode is realized.

[0023] (3) The cross-shaped slot structure is combined with the SIW planar multilayer feeding structure, supplemented by the design of a stepped metal horn structure, which significantly reduces the mutual interference and influence between ports and between different modes, and also achieves a significant reduction in antenna size and height, effectively realizing miniaturization and low-profile characteristics.

[0024] (4) The present invention has the characteristics of small size, low profile, simple structure, low manufacturing cost, etc., and can provide high antenna gain and broadband performance, and can be applied to large-scale TEM antenna arrays in modern communication systems.

[0025] (5) The TEM antenna has a wideband return loss (less than -10 dB) and a high gain of 8.2-10.9 dBi in both linear and circular polarization modes within the operating range of 18-19.5 GHz. When operating as a circularly polarized antenna, the antenna axial ratio (AR) is less than 3 dB within this frequency range.

[0026] The present invention is further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. 1 is a top view of a miniaturized broadband TEM antenna structure with dual linear polarization, dual circular polarization, and multiple modes in one embodiment.

[0028] Figure 2 This is a front view of a dual-linear-polarization dual-circular-polarization multi-mode miniaturized broadband TEM antenna structure in one embodiment.

[0029] Figure 3 Schematic diagram of the current and electric field direction of the SIW feeding layer when the port is fed in one embodiment, wherein Figure 3 (a) and (b) are the current and electric field direction of the SIW feeding layer when port 1 or port 2 is fed, respectively.

[0030] Figure 4 Schematic diagram of the electric field direction and magnetic field direction of the TEM antenna when port 1 is fed in one embodiment, where Figure 4 (a) and (b) are schematic diagrams of the electric field direction and magnetic field direction, respectively.

[0031] Figure 5 Schematic diagram of the electric field direction and magnetic field direction of the TEM antenna when port 2 is fed in one embodiment, where Figure 5 (a) and (b) are schematic diagrams of the electric field direction and magnetic field direction, respectively.

[0032] Figure 6 Schematic diagram of the S parameters of the TEM antenna in linear polarization mode in one embodiment, wherein Figure 6(a) and (b) are the S parameters of the TEM antenna when port 1 and port 2 are fed separately.

[0033] Figure 7 FIG is an example of a far-field radiation pattern of a linearly polarized mode of a TEM antenna at 19 GHz when port 1 is fed, wherein Figure 7 (a) and (b) are examples of the far-field radiation patterns of the YOZ plane (E plane) and XOZ plane (H plane) of the linear polarization mode at 19 GHz.

[0034] Figure 8 FIG is an example of a far-field radiation pattern of a linearly polarized mode of a TEM antenna at 19 GHz when port 2 is fed, where Figure 8 (a) and (b) are examples of the far-field radiation patterns of the linearly polarized mode in the XOZ plane (E plane) and YOZ plane (H plane) at 19 GHz.

[0035] Figure 9 FIG1 is an example diagram of the far-field radiation pattern of the circular polarization mode of the TEM antenna at 19 GHz when port 1 and port 2 are fed simultaneously and the phase difference is 90 degrees in one embodiment, wherein Figure 9 (a) and (b) are examples of the far-field radiation patterns of the YOZ plane and XOZ plane of the circularly polarized mode at 19 GHz.

[0036] Figure 10 1 is an example diagram of the simulated and tested antenna gain of a TEM antenna in a linear polarization mode in the frequency range of 18 GHz to 19.5 GHz in one embodiment.

[0037] Figure 11 1 is an example diagram of the simulated and tested antenna gain of the circularly polarized mode of the TEM antenna in the frequency range of 18 GHz to 19.5 GHz in one embodiment.

[0038] Figure 12 1 is an example diagram of the simulation of the circular polarization mode of the TEM antenna in the frequency range of 18 GHz to 19.5 GHz and the circular polarization axial ratio (AR) of the tested antenna in one embodiment. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0040] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] In one embodiment, a miniaturized wideband TEM antenna with dual linear polarization, dual circular polarization and multi-mode is provided. The antenna includes a dual linear polarization mode and a dual circular polarization mode, and mode switching selection is achieved through multi-port control; specifically: the antenna achieves the selection of the dual linear polarization mode and the dual circular polarization mode by controlling the feeding amplitude and phase difference of the multiple ports.

[0043] Furthermore, in one embodiment, the multi-port includes two mutually perpendicular ports, port 1 and port 2;

[0044] When the dual linear polarization mode is implemented: when the port 1 is fed alone, the TEM antenna implements radiation in a linear polarization mode with the electric field direction along a first direction; when the port 2 is fed alone, the TEM antenna implements radiation in a linear polarization mode with the electric field direction along a second direction; the first direction and the second direction are perpendicular to each other;

[0045] When the dual circular polarization mode is implemented: when port 1 and port 2 are fed simultaneously and port 1 leads port 2 with a phase difference of 90 degrees, the TEM antenna realizes right-hand circular polarization mode radiation; when port 1 and port 2 are fed simultaneously and port 2 leads port 1 with a phase difference of 90 degrees, the TEM antenna realizes left-hand circular polarization mode radiation.

[0046] Furthermore, in one embodiment, in combination Figure 1The antenna includes a metal horn portion and a SIW feeding portion, the SIW feeding portion including an upper SIW feeding structure and a lower SIW feeding structure arranged sequentially from top to bottom, a first SIW port being provided in the upper SIW feeding structure as the port 1, and a second SIW port being provided in the lower SIW feeding structure as the port 2, a cross-shaped slot structure being provided on the metal layer at the connection between the metal horn portion and the upper SIW feeding structure, and the two sides of the "cross" are respectively along the first direction and the second direction, and are used for feeding port 2 and port 1, respectively; a straight-line rectangular slot structure is provided on the metal layer at the connection between the upper SIW feeding structure and the lower SIW feeding structure, the straight-line rectangular slot structure being provided along the first direction and being located directly below the slot along the first direction in the cross-shaped slot structure.

[0047] Here, preferably, a coordinate system is established based on the antenna top view, with the horizontal direction as the x-axis, the vertical direction as the y-axis, the x-axis as the second direction, and the y-axis as the first direction.

[0048] When feeding port 1 of the top-layer feed structure (i.e., the upper SIW feed structure), the current has a smaller impact on the narrow side of the slot along the Y axis, but a greater impact on the wide side along the X axis. Therefore, the generated radiated electric field is primarily along the Y axis. Due to the orthogonal cross shape of the slot structure, the mutual influence between the feeds in each layer is minimal, resulting in high isolation. When feeding port 2 of the bottom-layer feed structure (i.e., the lower SIW feed structure), the current has a smaller impact on the narrow side of the slot along the X axis, but a greater impact on the wide side along the Y axis. Therefore, the generated radiated electric field is primarily along the X axis.

[0049] Combine Figures 2 to 5 The TEM antenna design of this invention excites quasi-TEM waves, whose electric and magnetic fields are perpendicular to each other and lie in the XOY plane. The propagation direction is along the Z axis and perpendicular to both the electric and magnetic fields. The cross-slot structure ensures high isolation between the two input ports, enabling independent operation of two orthogonal linear polarizations. This facilitates the generation of selectable left-handed or right-handed circularly polarized waves from two orthogonal linearly polarized waves (with a phase difference of ±90 degrees).

[0050] Preferably, in some embodiments, the length of the cross-shaped slot structure and the straight rectangular slot structure does not exceed the range of the metal horn part.

[0051] Preferably, in some embodiments, the structural parameters of the slits along the first direction in the cross-shaped slit structure are the same as the structural parameters of the straight rectangular slits. Here, the structural parameters include length, width, etc.

[0052] Preferably, in some embodiments, the upper SIW feeding structure includes a first metal layer, a first dielectric layer and a second metal layer arranged in sequence from top to bottom, the lower SIW feeding structure includes a second metal layer, a second dielectric layer and a third metal layer arranged in sequence from top to bottom, and a waveguide structure with metal vias on the side; the cross-shaped slot structure is arranged on the first metal layer, and the I-shaped rectangular slot structure is arranged on the second metal layer.

[0053] Preferably, in some embodiments, the metal horn portion is a stepped structure.

[0054] It is further preferred here that the metal horn part includes four stepped rectangular metal blocks, each of which is a narrow upper part and wide lower part structure; the four stepped rectangular metal blocks are respectively located in the four quadrants formed by the cross-shaped gap structure and are connected at the bottom, and two of the stepped rectangular metal blocks constitute a horn structure.

[0055] It is further preferred here that the four stepped rectangular metal blocks are symmetrically arranged about the center of the cross-shaped gap structure.

[0056] Furthermore, in one embodiment, both SIW ports are matched with an externally connected 50Ω coaxial cable structure through a conversion structure of SIW layers and microstrips.

[0057] It should be noted that the present invention is not limited to the structures in the above embodiments, and other structures with the same implementation principles as the present invention also fall within the protection scope of the present invention.

[0058] As a specific example, in one of the embodiments, the present invention is further verified and explained in detail.

[0059] In this example, the TEM antenna of the present invention is designed in detail. The size of the TEM antenna is designed to be 8 mm × 10 mm (about 0.5λ × 0.6λ), and the antenna height is 6.9 mm (about 0.4λ), where λ is the wavelength at the central operating frequency.

[0060] The stepped metal part of the antenna of the present invention is made of copper, and the two layers of the multi-layer feed structure are both made of RO4003C PCB boards. The dielectric layer thickness Hd is 1.524mm, the dielectric constant is 3.55, and the loss factor is 0.0027. Figure 1 and Figure 2,The specific design of each size parameter is as follows: the overall length of the metal horn structure A1=8mm, the overall width of the metal horn structure A2=10mm, the length of the rectangular slot of the cross slot structure along the X direction L1=10mm, the width of the rectangular slot of the cross slot structure along the X direction W1=0.48mm, the length of the rectangular slot of the cross slot structure along the Y direction L2=6.35mm, the width of the rectangular slot of the cross slot structure along the Y direction W2=0.95mm, the width of the SIW waveguide structure W SIW =11.5mm, the length L of the rectangular metal block on the top of the stepped metal speaker structure a1 =2.45mm, the width W of the rectangular metal block on the top layer of the stepped metal speaker structure a1 =4.03mm, the length L of the rectangular metal block at the bottom of the stepped metal speaker structure a2 =3.05mm, the width W of the rectangular metal block at the bottom of the stepped metal speaker structure a2 =4.38mm, the height of the rectangular metal block on the top layer of the stepped metal speaker structure is H1=1.6mm, the height of the rectangular metal block on the bottom layer of the stepped metal speaker structure is H2=1.6mm, the thickness of the PCB metal layer is H c =0.035mm, the thickness of the PCB dielectric layer H d =1.524mm.

[0061] Through simulation and test verification, combined with Figure 6 It can be seen that this TEM antenna provides a broadband return loss of less than -10 dB within the design frequency band of 17.5 GHz to 20 GHz when feeding from either port 1 or port 2. Taking port 2 as an example, considering the phase shift of feed lines at different layers, a 90-degree phase shift difference from port 1 is achieved by adding a 9 mm SIW feed line at port 2, thus generating right-hand circularly polarized waves.

[0062] Figures 7 to 9 The simulation and test far-field diagrams of the linear polarization of this TEM antenna at a frequency of 19 GHz when fed at port 1 or port 2 are shown, as well as the simulation and test far-field diagrams of right-hand circular polarization obtained by controlling a 90-degree phase difference when feeding ports 1 and 2 simultaneously. These diagrams show the linearly polarized and circularly polarized wave radiation excited by this TEM antenna in different modes.

[0063] Combine Figure 10 ,It can be seen that in the designed frequency range of 18 GHz to 19.5 GHz (8%), when port 1 is fed alone, the linear polarization mode simulation and measured antenna gain of the TEM antenna range from 8.5 to 10.9 dBi, and when port 2 is fed alone, the linear polarization mode simulation and measured antenna gain of the TEM antenna range from 8.2 to 10.1 dBi.

[0064] Combine Figure 11,It can be seen that the simulated and tested antenna gains of the TEM antenna circularly polarized mode in the range of 18GHz to 19.5GHz (8%) range from 8.4dBi to 9.8dBi; Figure 12 ,It can be seen that the simulation and test results of the axial ratio (AR) are both less than 3dB in this frequency range.

[0065] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only illustrative of the principles of the present invention. Without departing from the spirit and scope of the present invention, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A miniaturized broadband TEM antenna with dual linear polarization, dual circular polarization and multi-mode, characterized in that: The antenna includes dual linear polarization mode and dual circular polarization mode, and realizes mode switching selection through multi-port control; the antenna realizes the selection of dual linear polarization mode and dual circular polarization mode by controlling the feeding amplitude and phase difference of the multi-port; The multi-port includes two mutually perpendicular ports 1 and 2; When the dual linear polarization mode is implemented: the port 1 is fed alone, and the TEM antenna implements linear polarization mode radiation with the electric field direction along the first direction; The port 2 is fed separately, and the TEM antenna realizes linear polarization mode radiation with the electric field direction along the second direction; the first direction and the second direction are perpendicular to each other; When the dual circular polarization mode is realized: when port 1 and port 2 are fed simultaneously and port 1 leads port 2 with a phase difference of 90 degrees, the TEM antenna realizes right-hand circular polarization mode radiation; when port 1 and port 2 are fed simultaneously and port 2 leads port 1 with a phase difference of 90 degrees, the TEM antenna realizes left-hand circular polarization mode radiation; The antenna includes a metal horn portion and a SIW feed portion. The SIW feed portion includes an upper SIW feed structure and a lower SIW feed structure arranged sequentially from top to bottom. A first SIW port is provided in the upper SIW feed structure, serving as the port 1, and a second SIW port is provided in the lower SIW feed structure, serving as the port 2. A cross-shaped slot structure is provided on the metal layer at the connection between the metal horn portion and the upper SIW feed structure, and the two sides of the "cross" are respectively along the first direction and the second direction, and are used for feeding port 2 and port 1, respectively; a straight-line rectangular slot structure is provided on the metal layer at the connection between the upper SIW feed structure and the lower SIW feed structure. The straight-line rectangular slot structure is arranged along the first direction and is located directly below the slot along the first direction in the cross-shaped slot structure.

2. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 1, characterized in that: The lengths of the cross-shaped slot structure and the straight rectangular slot structure do not exceed the range of the metal horn portion.

3. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 1, characterized in that: The structural parameters of the slots along the first direction in the cross-shaped slot structure are the same as the structural parameters of the straight rectangular slots.

4. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 1, characterized in that: The upper SIW feed structure includes a first metal layer, a first dielectric layer, and a second metal layer arranged in sequence from top to bottom, and the lower SIW feed structure includes a second metal layer, a second dielectric layer, and a third metal layer arranged in sequence from top to bottom; the cross-shaped slot structure is arranged on the first metal layer, and the straight rectangular slot structure is arranged on the second metal layer.

5. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 1, characterized in that: The metal speaker part has a stepped structure.

6. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 5, characterized in that: The metal speaker part includes four stepped rectangular metal blocks, each of which is narrow at the top and wide at the bottom; the four stepped rectangular metal blocks are respectively located in the four quadrants formed by the cross-shaped gap structure and are connected at the bottom, and two stepped rectangular metal blocks constitute a speaker structure.

7. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 6, characterized in that: The four stepped rectangular metal blocks are symmetrically arranged about the center of the cross-shaped gap structure.

8. The dual-linear-dual-circular-polarization multi-mode miniaturized broadband TEM antenna according to claim 1, characterized in that: Both SIW ports are matched with the external 50Ω coaxial cable structure through the conversion structure of each layer of SIW and microstrip.

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