Coupled-fed all-metal millimeter-wave dual-polarized filtered antenna

Abstract

The application discloses a coupled feeding full-metal millimeter wave dual-polarized filtering antenna, which comprises a full-metal millimeter wave dual-polarized filtering antenna and a conversion structure of a coupled waveguide to a microstrip line on a multilayer PCB (printed circuit board); the full-metal millimeter wave dual-polarized filtering antenna comprises a compact cross-shaped dual-polarized radiator at the top and a plurality of cascaded four-ridge waveguide sections and a disappearing square waveguide section inside; the conversion structure of the coupled waveguide to the microstrip line on the multilayer PCB comprises a four-ridge waveguide matching section part connected to the full-metal millimeter wave dual-polarized filtering antenna, a coupling slot part, a feeding probe on the multilayer PCB, a coupling patch, a quasi-coaxial transmission line and a microstrip line. The application can effectively work in a 5G millimeter wave n257 frequency band (26.5 GHz-29.5 GHz) and is driven by a commercial millimeter wave multi-channel beam forming chip. The antenna can realize a half-wavelength pitch array and is suitable for application of a 5G millimeter wave phased array antenna.

Description

Technical Field

[0001] This invention relates to the fields of electronics and wireless communication technology, and in particular to a coupled-fed all-metal millimeter-wave dual-polarized filter antenna. Background Technology

[0002] To meet the system requirements of fifth-generation wireless communication, phased array antenna systems in the millimeter-wave band have received widespread attention. In millimeter-wave integrated phased array systems, thanks to the maturity and application of beamforming chips, millimeter-wave array antennas, active beamforming networks, and other auxiliary circuits can be easily integrated onto a multi-layer PCB (printed circuit board). Given the extremely limited design space constraints of active array antennas, the design concept of filtering antennas allows for tight integration of the antenna and filter at both the design and structural levels. However, traditional PCB-based filtering antenna designs are affected by dielectric losses, exhibiting high loss and low Q values. Due to the influence of the resonator structure, they cannot simultaneously provide a compact structure and filtering characteristics. All-metal filtering antennas are immune to dielectric losses and hold promise for achieving better filtering characteristics in the millimeter-wave band.

[0003] Furthermore, the connection method between the feed circuit and the all-metal antenna in 5G millimeter-wave phased array systems has been widely discussed. Early methods tended to use cables or long transmission lines to connect the RF channel and antenna elements. However, with the maturity and application of smaller 5G millimeter-wave beamforming chips, it has become impractical to install RF connectors within the compact area of ​​antenna elements or subarrays. Therefore, connectorless feeding methods are favored due to their compact size when mounting discrete antennas. Antennas are typically connected to the feed circuit via surface-mount soldering. However, this method still suffers from low reliability and complex processes in array antenna soldering. A specially designed coupled feeding method promises to achieve efficient feeding and simplified assembly between the active feed network on a multi-layer PCB and the all-metal antenna. Summary of the Invention

[0004] Technical Title: This invention provides a coupled-fed all-metal millimeter-wave dual-polarized filter antenna. This antenna structure enables the realization of an all-metal filter antenna within a compact antenna element space and integrates with an active feed network via coupled feeding. This antenna can cover the required millimeter-wave frequency band and provides reliable filter antenna performance.

[0005] Technical Solution: The present invention provides a coupled-fed all-metal millimeter-wave dual-polarized filter antenna comprising an all-metal millimeter-wave dual-polarized filter antenna and a conversion structure from a coupled waveguide to a quasi-coaxial line on a multilayer PCB; wherein the all-metal millimeter-wave dual-polarized filter antenna comprises a compact cross-shaped dual-polarized radiator at the top, multiple lost-mode square waveguide sections alternately cascaded inside the metal waveguide, and multiple four-ridged waveguide sections, that is: arranged from top to bottom in the following order: compact cross-shaped dual-polarized radiator, first lost-mode square waveguide section, first four-ridged waveguide section, second lost-mode square waveguide section, second four-ridged waveguide section, and so on. The three vanishing mode square waveguide section, the third four-ridge waveguide section, and the fourth vanishing mode square waveguide section; the conversion structure from the coupled waveguide to the pseudo-coaxial line on the multilayer PCB includes a four-ridge waveguide matching section connecting the all-metal millimeter-wave dual-polarized filter antenna and a multilayer PCB (13); the four-ridge waveguide matching section includes two sections with different ridge thicknesses: the first four-ridge waveguide matching section and the second four-ridge waveguide matching section. A coupling slot is provided below the second four-ridge waveguide matching section, and a multilayer PCB (13) is provided below the coupling slot. The antenna is fed by a beamforming chip connected to a microstrip line port designed on the back of the multilayer PCB.

[0006] The multiple vanishing mode square waveguide sections and multiple four-ridged waveguide sections are alternately cascaded in the normal direction of the antenna's radiating aperture.

[0007] The compact cross-shaped dual-polarized radiator has two mutually perpendicular intersecting air gaps etched in the middle, and a short air gap perpendicular to the air gap is etched at each of the four outer ends of the two mutually perpendicular intersecting air gaps.

[0008] The aforementioned conversion structure from a coupled waveguide to a quasi-coaxial line on a multilayer PCB adopts a coupled feeding method, with coupling gaps provided between the horizontal polarization probe, the vertical polarization probe, and the four-ridge waveguide matching section.

[0009] The aforementioned conversion structure from a coupled waveguide to a quasi-coaxial line on a multilayer PCB employs coupling patches placed perpendicularly to each other, which are connected to the horizontal polarization probe and the vertical polarization probe, respectively.

[0010] The first, second, and third four-ridge waveguide sections have rectangular conductive walls in cross-section. A short conductive metal ridge is connected to each of the four sides of the inner side of the rectangular conductive wall. The outer ends of the four short conductive metal ridges are connected to the inner side of the conductive wall, and the inner ends of the four short conductive metal ridges point to the center of the rectangular conductive wall, but are not connected to each other.

[0011] The first, second, third, and fourth lost-mode square waveguide sections have rectangular conductive walls in cross-section, and the rectangular conductive walls contain cavities.

[0012] The aforementioned four-ridge waveguide matching section connects two metal ridge waveguides with different ridge thicknesses, namely the first four-ridge waveguide matching section and the second four-ridge waveguide matching section, with the coupling gap located below the second four-ridge waveguide section in the four-ridge waveguide matching section.

[0013] The multilayer PCB is provided with a quasi-coaxial transmission line, a horizontal polarization probe, a vertical polarization probe, a coupling patch that is perpendicularly placed and connected to the horizontal polarization probe and the vertical polarization probe, and a via enclosure surrounding the above structure in the multilayer PCB.

[0014] The multilayer PCB (13) includes a first metal layer, a first dielectric substrate, a second metal layer, a first adhesive layer, a third metal layer, a second dielectric substrate, a fourth metal layer, a second adhesive layer, a fifth metal layer, a third dielectric substrate, and a sixth metal layer arranged sequentially from top to bottom; wherein horizontal polarization probes and vertical polarization probes pass through all dielectric substrates from top to bottom, and their lower parts are connected to microstrip ports; the upper part of the vertical polarization probes is connected to coupling patches.

[0015] Beneficial Effects: The coupled-fed all-metal millimeter-wave dual-polarized filter antenna described above has an antenna structure based on a vanishing-mode waveguide filter design. Compared to filter antennas based on rectangular waveguides, the vanishing-mode waveguide allows for a compact resonator size, enabling the designed filter antenna to be arrayed at half-wavelength spacing. The compact cross-shaped dual-polarized radiator at the top of the antenna can also serve as the last resonator section of the filter antenna, forming a fourth-order filter response together with the other three resonators in the metal filter antenna, achieving excellent filtering characteristics.

[0016] The aforementioned waveguide-to-quasi-coaxial conversion structure on a multilayer PCB utilizes a four-ridged waveguide matching section to optimize conversion efficiency. The coupling gap between the four-ridged waveguide matching section and the coupling patch on the multilayer PCB enables a non-contact signal connection from the multilayer PCB to the metal four-ridged waveguide, facilitating antenna integration and assembly. The coupling patches, placed perpendicularly on the multilayer PCB, are fed by horizontal and vertical polarization probes, easily achieving dual-polarization feeding within a limited space.

[0017] In summary, this all-metal filter antenna structure can integrate filters and radiators within a compact space. Furthermore, it can be integrated with feed circuits in multi-layer boards via a coupled feed structure, making the antenna well-suited for applications in 5G millimeter-wave phased arrays and highly practical. This antenna can cover the required millimeter-wave frequency bands, providing reliable antenna performance. In addition, the antenna also boasts advantages such as ease of fabrication and good heat dissipation. Attached Figure Description

[0018] Figure 1This is a schematic cross-sectional view of the coupled-fed all-metal millimeter-wave dual-polarized filter antenna provided by the present invention.

[0019] Figure 2 This is a partial cross-sectional schematic diagram of the all-metal millimeter-wave dual-polarized filter antenna provided by the present invention.

[0020] Figure 3 This is a schematic diagram of the PCB stack-up structure in the conversion structure from a coupled waveguide to a quasi-coaxial line on a multilayer PCB.

[0021] Figure 4 This is a schematic diagram of an active array design for a coupled-fed all-metal millimeter-wave dual-polarized filter antenna.

[0022] Figure 5 The measured radiation pattern results are obtained by scanning the horizontal polarized beam of the active array of a coupled-fed all-metal millimeter-wave dual-polarized filter antenna in the azimuth and elevation planes.

[0023] Figure 6 The measured radiation pattern results are obtained by scanning the vertical polarization beam of the active array of a coupled-fed all-metal millimeter-wave dual-polarization filter antenna in the azimuth and elevation planes.

[0024] Figure 7 It is the measured frequency response of the vertical and horizontal polarized beams of the active array of a coupled-fed all-metal millimeter-wave dual-polarized filter antenna when scanning the azimuth plane.

[0025] The diagram includes: 1. Compact cross-shaped dual-polarized radiator; 2. First lost-mode square waveguide section; 3. Second lost-mode square waveguide section; 4. Third lost-mode square waveguide section; 5. Fourth lost-mode square waveguide section; 6. First four-ridge waveguide section; 7. Second four-ridge waveguide section; 8. Third four-ridge waveguide section; 9. Four-ridge waveguide matching section; 10. First four-ridge waveguide matching section; 11. Second four-ridge waveguide matching section; 12. Coupling slot; 13. Multilayer PCB; 14. Quasi-coaxial transmission line; 15. Horizontal polarization probe; 16. Vertical polarization probe; 17. Coupling patch; 18. Via enclosure; 19. Microstrip port; 20. Beamforming chip; 21. Intersecting perpendicular air gaps; 22. Short conductive metal ridges.

[0026] First metal layer M1, second metal layer M2, third metal layer M3, fourth metal layer M4, fifth metal layer M5, sixth metal layer M6; first dielectric substrate 23, first adhesive layer 24, second dielectric substrate 25, second adhesive layer 26, third dielectric substrate 27. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

[0028] Reference Appendix Figure 1 - Appendix Figure 4 The coupled-fed all-metal millimeter-wave dual-polarized filter antenna provided by this invention includes an all-metal millimeter-wave dual-polarized filter antenna and a conversion structure from a coupled waveguide to a quasi-coaxial line on a multi-layer PCB; wherein the all-metal millimeter-wave dual-polarized filter antenna includes a compact cross-shaped dual-polarized radiator 1 at the top, multiple lost-mode square waveguide sections alternately cascaded inside the metal waveguide, and multiple four-ridged waveguide sections, that is: arranged from top to bottom as follows: compact cross-shaped dual-polarized radiator 1, first lost-mode square waveguide section 2, first four-ridged waveguide section 6, second lost-mode square waveguide section 3, second four-ridged waveguide section 7, and third lost-mode square waveguide section. 4. Third and fourth ridge waveguide section 8, fourth vanishing mode square waveguide section 5; The conversion structure from the coupled waveguide to the quasi-coaxial line on the multilayer PCB includes a four-ridge waveguide matching section 9 and a multilayer PCB 13 connecting the all-metal millimeter-wave dual-polarized filter antenna; The four-ridge waveguide matching section 9 includes two sections: a first four-ridge waveguide matching section 10 and a second four-ridge waveguide matching section 11 with different ridge thicknesses. A coupling slot 12 is provided below the second four-ridge waveguide matching section 11, and a multilayer PCB 13 is provided below the coupling slot 12. The antenna is fed by a beamforming chip 20 connected to a microstrip line port 19 designed on the back of the multilayer PCB 13.

[0029] The compact cross-shaped dual-polarized radiator and cascaded lost-mode waveguide resonator section are described. The compact cross-shaped dual-polarized radiator is designed by forking and bending the ends of a cross-shaped dual-polarized radiator, resulting in a compact structure that can be used as the last resonator in a filter antenna. The compact cross-shaped dual-polarized radiator 1 has two mutually perpendicular intersecting air gaps 21 etched in its center, and a short air gap perpendicular to each of the two intersecting air gaps etched at each of the four outer ends of the two intersecting air gaps.

[0030] The cascaded lost-mode waveguide resonator section includes multiple lost-mode square waveguide sections and multiple four-ridged waveguide sections cascaded alternately in the normal direction of the antenna's radiating aperture, so that the compact cross-shaped dual-polarized radiator can together form a fourth-order response filtered antenna. Each lost-mode waveguide resonator section includes a four-ridged waveguide section and lost-mode square waveguide sections on its upper and lower sides. The gap between a pair of ridges in the four-ridged waveguide section corresponds to the capacitance in the resonator, and the lost-mode square waveguide corresponds to the inductance in the resonator.

[0031] In terms of antenna size, the size of the vanishing mode square waveguide below the cutoff wavelength can be much smaller than half the wavelength. At the same time, the cutoff frequency of the four-ridge waveguide is also low, making it easy to achieve a small cross-sectional size. The entire all-metal dual-polarized filter antenna unit can be arrayed at half the wavelength.

[0032] In a coupled waveguide-to-quasi-coaxial line conversion structure, such as... Figure 1 and Figure 3 As shown, the key structures include a four-ridged waveguide matching section 9 connecting the all-metal millimeter-wave dual-polarized filter antenna, a coupling slot 12 below, a quasi-coaxial transmission line 14 on the multilayer PCB 13, a horizontal polarization probe 15, a vertical polarization probe 16, mutually perpendicularly placed coupling patches 17 connected to the probes, and a via fence 18 surrounding the above structures in the multilayer PCB 13. The antenna can be fed by a beamforming chip 20 connected to a microstrip line port 19 designed on the back of the multilayer PCB.

[0033] The function achieved by the coupled waveguide-to-quasi-coaxial line conversion structure is to convert energy from the quasi-TEM mode in the coaxial line transmission line to the TE mode in the waveguide. 10 The signal is fed vertically and horizontally polarized into a 50Ω microstrip line on the bottom layer of the PCB, then through a quasi-coaxial transmission line to a feed probe. Part of the signal is coupled to a waveguide ridge via a via pad or microstrip line on the quasi-coaxial line side, while the other part is simultaneously coupled to a waveguide ridge on the opposite side of the quasi-coaxial transmission line via a coupling patch on the feed probe. Ultimately, a balanced, equal-amplitude, out-of-phase excitation is generated beneath a pair of opposing waveguide ridges in the metal waveguide. Therefore, the TE in the four-ridge lost-mode waveguide... 10 The pattern can be successfully triggered.

[0034] The first four-ridge waveguide section 6, the second four-ridge waveguide section 7, and the third four-ridge waveguide section 8 have rectangular conductive walls in cross-section. A short conductive metal ridge 22 is connected to each of the four inner sides of this rectangular conductive wall. The outer ends of these four short conductive metal ridges connect to the inner side of the conductive wall, and the inner ends of these four short conductive metal ridges point towards the center of the rectangular conductive wall, but are not connected to each other. The first lost-mode square waveguide section 2, the second lost-mode square waveguide section 3, the third lost-mode square waveguide section 4, and the fourth lost-mode square waveguide section 5 have rectangular conductive walls in cross-section, with cavities inside the rectangular conductive walls. The four-ridge waveguide matching section 9 connects two metal ridge waveguides with different ridge thicknesses, namely the first four-ridge waveguide matching section 10 and the second four-ridge waveguide matching section 11. The coupling gap 12 is located below the second four-ridge waveguide matching section 11 in the four-ridge waveguide matching section 9.

[0035] The multilayer PCB 13 includes, from top to bottom, a first metal layer M1, a first dielectric substrate 23, a second metal layer M2, a first adhesive layer 24, a third metal layer M3, a second dielectric substrate 25, a fourth metal layer M4, a second adhesive layer 26, a fifth metal layer M5, a third dielectric substrate 27, and a sixth metal layer M6; wherein the horizontal polarization probe 15 and the vertical polarization probe 16 pass through all the dielectric substrates from top to bottom, and their lower parts are connected to the microstrip line port 19; the upper part of the vertical polarization probe 16 is connected to the coupling patch 17.

[0036] Due to the half-wavelength array characteristics of coupled-fed all-metal millimeter-wave dual-polarized filter antennas, the antennas can be arrayed on the plane of the radiating aperture and fed through an active beamforming network. Figure 4 The diagram shows the design of an active array. The all-metal array antenna is mounted on one side of a multilayer PCB. An active beamforming network based on an active beamforming chip is designed on the back of the PCB. The design of the network is not special and will not be described in detail here.

[0037] To verify the authenticity and reliability of the coupled-fed all-metal millimeter-wave dual-polarized filter antenna provided in this invention, an active dual-polarized array antenna operating in the 26.5GHz to 29.5GHz frequency band was fabricated according to this embodiment. The array size is 4×4. The 10-layer PCB board was designed and fabricated based on a DS-3 dielectric substrate and a Rogers 4450F bonding layer. Sixteen four-ridged lost-mode waveguide-to-quasi-coaxial transition structures were designed in the active array, with the structures in the multi-layer PCB mainly occupying the first to fourth layers. Four 8-channel millimeter-wave beamforming chips were used to excite a total of 32 channels across the 16 antenna elements. (Appendix) Figure 5 - Appendix Figure 6 The radiation pattern results of the physical array antenna are presented. Experimental results show that, after calibration, the active antenna array can achieve beam scanning within ±45° in both the horizontal and vertical polarization planes. Furthermore, compared to the RF channel response, the proposed antenna array provides additional suppression in the stopband. Additionally, it can be observed that gain jitter occurs during large-angle scanning due to deterioration in the active input impedance matching. In the 26.5 GHz to 29.8 GHz band, the gain ripple of the normal beam in the passband is less than 3 dB. In the low-frequency band, a measured stopband suppression of 15 dB is achieved at 25.6 GHz, and around 24.6 GHz, a measured stopband suppression of 30 dB is achieved. In the high-frequency band, a measured stopband suppression of 15 dB is achieved at 30.7 GHz, and around 31.4 GHz, a measured stopband suppression of 30 dB is achieved. The test results show that the filter antenna array included in this patent can maintain good filtering characteristics when the main beam is scanned to different angles.

[0038] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A coupled-fed all-metal millimeter-wave dual-polarized filter antenna, characterized in that, The antenna comprises an all-metal millimeter-wave dual-polarized filter antenna and a conversion structure from a coupled waveguide to a quasi-coaxial line on a multi-layer PCB; the all-metal millimeter-wave dual-polarized filter antenna includes a compact cross-shaped dual-polarized radiator (1) at the top, multiple lost-mode square waveguide sections alternately cascaded inside the metal waveguide, and multiple four-ridged waveguide sections, that is: arranged from top to bottom as follows: compact cross-shaped dual-polarized radiator (1), first lost-mode square waveguide section (2), first four-ridged waveguide section (6), second lost-mode square waveguide section (3), second four-ridged waveguide section (7), third lost-mode square waveguide section (4), third four-ridged waveguide section (8), fourth lost-mode square waveguide section (9), fourth lost-mode square waveguide section ... second lost-mode square waveguide section (2), third lost-mode square waveguide section (3), fourth lost-mode square waveguide section (4), third lost-mode square waveguide section (5), fourth lost-mode square waveguide section (6), fourth lost-mode square waveguide section (7), third lost-mode square waveguide section (8), fourth lost-mode square waveguide section (9), fourth lost-mode square waveguide section (1), second lost-mode square waveguide section (1), second lost-mode square waveguide section (1), second lost-mode square waveguide section (1), third lost-mode square waveguide section (1), fourth lost-mode square waveguide section (1), third lost-mode square waveguide section (1), fourth lost-mode square waveguide section (1), third lost-mode square waveguide section (1), fourth lost-mode square waveguide section (1), third lost- The transformation structure from the coupled waveguide to the pseudo-coaxial line on the multilayer PCB includes a four-ridged waveguide matching section (9) connecting the all-metal millimeter-wave dual-polarized filter antenna and a multilayer PCB (13); the four-ridged waveguide matching section (9) includes two sections with different ridge thicknesses: a first four-ridged waveguide matching section (10) and a second four-ridged waveguide matching section (11). A coupling slot (12) is provided below the second four-ridged waveguide matching section (11), and a multilayer PCB (13) is provided below the coupling slot (12). The antenna is fed by a beamforming chip (20) connected to a microstrip line port (19) designed on the back of the multilayer PCB (13). The multiple vanishing mode square waveguide sections and multiple four-ridged waveguide sections are alternately cascaded in the normal direction of the antenna's radiating aperture. The first four-ridge waveguide section (6), the second four-ridge waveguide section (7), and the third four-ridge waveguide section (8) have rectangular conductive walls in cross-section. A short conductive metal ridge (22) is connected to each of the four sides inside the rectangular conductive wall. The outer ends of the four short conductive metal ridges are connected to the inner side of the conductive wall, and the inner ends of the four short conductive metal ridges point to the center of the rectangular conductive wall, but are not connected to each other. The first lost-mode square waveguide section (2), the second lost-mode square waveguide section (3), the third lost-mode square waveguide section (4), and the fourth lost-mode square waveguide section (5) have rectangular conductive walls in their cross-sections, and the rectangular conductive walls are cavities.

2. The coupled-fed all-metal millimeter-wave dual-polarized filter antenna as described in claim 1, characterized in that, The compact cross-shaped dual-polarized radiator (1) has two mutually perpendicular intersecting air gaps (21) etched in the middle, and a short air gap perpendicular to the air gap is etched at each of the four outer ends of the two mutually perpendicular intersecting air gaps.

3. The coupled-fed all-metal millimeter-wave dual-polarized filter antenna as described in claim 1, characterized in that, The aforementioned conversion structure from the coupled waveguide to the pseudo-coaxial line on the multilayer PCB adopts a coupled feeding form, with a coupling gap (12) provided between the horizontal polarization probe (15), the vertical polarization probe (16) and the four-ridge waveguide matching section (9).

4. The coupled-fed all-metal millimeter-wave dual-polarized filter antenna as described in claim 1, characterized in that, The aforementioned conversion structure from the coupled waveguide to the pseudo-coaxial line on the multilayer PCB uses coupling patches (17) placed perpendicularly to each other, which are connected to the horizontal polarization probe (15) and the vertical polarization probe (16) respectively.

5. The coupled-fed all-metal millimeter-wave dual-polarized filter antenna as described in claim 1, characterized in that, The four-ridge waveguide matching section (9) is connected to two metal ridge waveguides with different ridge thicknesses, namely the first four-ridge waveguide matching section (10) and the second four-ridge waveguide matching section (11), and the coupling gap (12) is located below the second four-ridge waveguide matching section (11) in the four-ridge waveguide matching section (9).

6. The coupled-fed all-metal millimeter-wave dual-polarized filter antenna as described in claim 1, characterized in that, The multilayer PCB (13) is provided with a pseudo-coaxial transmission line (14), a horizontal polarization probe (15), a vertical polarization probe (16), a coupling patch (17) that is perpendicularly placed and connected to the horizontal polarization probe (15) and the vertical polarization probe (16), and a via fence (18) surrounding the above structure in the multilayer PCB (13).

7. The coupled-fed all-metal millimeter-wave dual-polarized filter antenna as described in claim 6, characterized in that, The multilayer PCB (13) includes a first metal layer (M1), a first dielectric substrate (23), a second metal layer (M2), a first adhesive layer (24), a third metal layer (M3), a second dielectric substrate (25), a fourth metal layer (M4), a second adhesive layer (26), a fifth metal layer (M5), a third dielectric substrate (27), and a sixth metal layer (M6) arranged sequentially from top to bottom; wherein the horizontal polarization probe (15) and the vertical polarization probe (16) pass through all dielectric substrates from top to bottom, and their lower parts are connected to the microstrip port (19) and their upper parts are connected to the coupling patch (17).

Images