A differential duplex filtering antenna with dual-slot symmetric excitation

Abstract

The present invention discloses a differential duplex filtering antenna with dual-slot symmetric excitation. The antenna includes an upper dielectric substrate, a lower dielectric substrate, a metal floor, a first metal feeding microstrip line, a second metal feeding microstrip line, a metal rectangular radiation patch, a coupling slot, a metal microstrip resonator, and a first metal microstrip open resonator, a second metal microstrip open resonator, a third metal microstrip open resonator, and a fourth metal microstrip open resonator. The present invention realizes functions of radiation, duplex synthesis, channel filtering, differential feeding, and balanced-unbalanced transformation with a compact structure, ensuring good cross-polarization performance, lobe symmetry, and duplex filtering radiation ability.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication antennas, and particularly to a differential duplex filtering antenna with dual-slot symmetric excitation. Background Art

[0002] In recent years, designing highly miniaturized and integrated radio frequency front modules has become the future development trend. Therefore, the design of radio frequency front-end systems with small size and high integration has also attracted the attention of researchers. With the in-depth study of the bandwidth broadening, cross-polarization, frequency selectivity, and radiation performance of filtering antennas, it has also laid a foundation for the research of duplex antennas. In a duplex antenna, the same antenna is used for both signal reception and signal transmission. Therefore, a duplex antenna can not only reduce costs but also reduce the volume of the system.

[0003] Traditionally, antennas and duplexers are designed separately, and finally, the filtering antenna is designed by connecting them in series through a 50Ω transmission line and a matching network, but this will increase the structural size and insertion loss. Filtering antennas are a new technology that has received much attention in recent years. In a filtering antenna, the antenna not only plays a role in radiation but also has a filtering function. Therefore, filtering antennas have a smaller size.

[0004] In the existing duplex antenna technology, there are still deficiencies in cross-polarization performance and the symmetry of radiation lobes (Y. Lee, J. Tarng and S. Chung, "A filtering diplexing antenna for dual-band operation with similar radiation patterns and low cross-polarization levels," in IEEE Antennas and Wireless Propagation Letters, vol. 16, pp. 58 - 61, 2017). Poor cross-polarization performance will affect the polarization purity of the antenna. On the one hand, it will lead to a decrease in communication efficiency, and on the other hand, it will cause interference. Asymmetric lobes are difficult to meet the requirements of some applications, such as measurement, positioning, etc.

[0005] Therefore, a duplex antenna with a compact structure, duplex filtering characteristics, good cross-polarization performance, and symmetric lobes is an important requirement in the fields of communication technology and antenna technology (H. Jin, G. Q. Luo, W. Che, K. Chin, Y. Pan, and Y. Yu, "Vertically-integrated differential filtering patch antenna excited by a balun bandpass filter," in IET Microwaves, Antennas & Propagation, vol. 13, no. 3, pp. 300-304, 27 Feb 2019). Summary of the Invention

[0006] The object of the present invention is to overcome the deficiencies of the prior art and provide a duplex filtering antenna that simultaneously has radiation, filtering, and duplex performance, and has good cross-polarization characteristics and symmetric radiation lobes. The present invention has the advantages of small size, high integration, low cross-polarization, and symmetric radiation lobes.

[0007] The object of the present invention can be achieved by at least the following technical solutions.

[0008] A differential duplex filtering antenna with dual-slot symmetric excitation, comprising an upper dielectric substrate, a lower dielectric substrate, a metal floor, a first metal feeding microstrip line, a second metal feeding microstrip line, a metal rectangular radiation patch, a coupling slot, a metal microstrip resonator, and a first metal microstrip open resonator, a second metal microstrip open resonator, a third metal microstrip open resonator, and a fourth metal microstrip open resonator;

[0009] The upper dielectric substrate, the metal floor, and the lower dielectric substrate are bonded together, and the metal floor is embedded between the upper dielectric substrate and the lower dielectric substrate; two parallel coupling slots are engraved on the metal floor;

[0010] The metal rectangular radiation patch is attached to the upper surface of the upper dielectric substrate, and the center of the metal rectangular radiation patch coincides with the center of the upper dielectric substrate. Its length is half of the waveguide wavelength, and its width is greater than the distance between the two coupling slots;

[0011] The first metal feed microstrip line, the second metal feed microstrip line, the metal microstrip resonator, and the first metal microstrip split-ring resonator, the second metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator are attached to the lower surface of the lower dielectric substrate. Among them, the second metal microstrip split-ring resonator, the first metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator are arranged in sequence from one side to the other side of the lower surface along the central axis of the lower dielectric substrate. The metal microstrip resonator passes through the center of the lower surface of the lower dielectric substrate and is located between the first metal microstrip split-ring resonator and the third metal microstrip split-ring resonator. The first metal feed microstrip line and the second metal feed microstrip line are respectively connected to the second metal microstrip split-ring resonator and the fourth metal microstrip split-ring resonator.

[0012] Furthermore, the upper dielectric substrate, the lower dielectric substrate, the metal floor, the metal rectangular radiation patch, the coupling slot, the metal microstrip resonator, and the first metal microstrip split-ring resonator, the second metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator all have a symmetric structure, and their symmetry planes coincide.

[0013] Furthermore, the two coupling slots are symmetrically distributed on both sides of the common symmetry plane of the upper dielectric substrate, the lower dielectric substrate, the metal floor, the metal rectangular radiation patch, the coupling slot, the metal microstrip resonator, and the first metal microstrip split-ring resonator, the second metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator. The distance between the two coupling slots is larger than the widths of the first metal microstrip split-ring resonator, the second metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator, and is shorter than the length of the metal microstrip resonator.

[0014] Furthermore, the metal microstrip resonator is a metal strip passing through the center of the lower surface of the lower dielectric substrate and is perpendicular to the common symmetry plane of the upper dielectric substrate, the lower dielectric substrate, the metal floor, the metal rectangular radiation patch, the coupling slot, and the first metal microstrip split-ring resonator, the second metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator.

[0015] Furthermore, the first metal microstrip split-ring resonator, the second metal microstrip split-ring resonator, the third metal microstrip split-ring resonator, and the fourth metal microstrip split-ring resonator are all rectangular rings surrounded by microstrip lines, and there is an opening in the middle of one side of the rectangular ring.

[0016] Furthermore, the first metal microstrip split-ring resonator and the third metal microstrip split-ring resonator are respectively distributed on both sides of the metal microstrip resonator, and the side of the rectangular ring parallel to the side with the opening is close to and parallel to the metal microstrip resonator;

[0017] The side with the opening in the second metal microstrip split-ring resonator is close to and parallel to the side with the opening in the first metal microstrip split-ring resonator; the side with the opening in the fourth metal microstrip split-ring resonator is close to and parallel to the side with the opening in the third metal microstrip split-ring resonator.

[0018] Furthermore, the second metal microstrip split-ring resonator is fed through the first metal feeding microstrip line; the fourth metal microstrip split-ring resonator is fed through the second metal feeding microstrip line;

[0019] One end of the first metal feeding microstrip line can be connected to any side of the second metal microstrip split-ring resonator, and the other end is connected to a feeding signal source; one end of the second metal feeding microstrip line can be connected to any side of the fourth metal microstrip split-ring resonator, and the other end is connected to a feeding signal source.

[0020] Furthermore, the upper dielectric substrate, the metal ground plane, and the metal rectangular radiation patch form a microstrip antenna. The metal microstrip resonator is mutually coupled with the microstrip antenna through a coupling slot to form a dual-band antenna, which resonates at two operating frequencies, namely the transmitting frequency and the receiving frequency. Due to the symmetry of the structure, that is, the upper dielectric substrate, the metal ground plane, the metal rectangular radiation patch, the metal microstrip resonator, and the coupling slot have a common symmetry plane. At the transmitting frequency and the receiving frequency, the field distribution on the dual-band antenna is symmetric about the symmetry plane, forming a dual-band differential antenna. Therefore, the radiation lobes are symmetric, and there is an inhibitory effect on cross polarization.

[0021] Furthermore, the metal microstrip resonator also functions to synthesize two signals, thereby forming a duplex antenna; the first metal microstrip open-loop resonator and the second metal microstrip open-loop resonator resonate at one resonance frequency of the dual-band antenna, and together with this resonance mode of the dual-band antenna, they form a filter for one channel. The third metal microstrip open-loop resonator and the fourth metal microstrip open-loop resonator resonate at the other resonance frequency of the dual-band antenna, and together with this resonance mode of the dual-band antenna, they form a filter for the other channel, enabling both channels of the duplex antenna to have filtering characteristics, thus forming a filtering antenna; since the first metal microstrip open-loop resonator, the second metal microstrip open-loop resonator, the third metal microstrip open-loop resonator, and the fourth metal microstrip open-loop resonator all have symmetric structures and the same symmetry plane as the dual-band antenna, both channel filters are differential filters, ensuring the differential excitation of the dual-band antenna, and thus ensuring good cross-polarization performance and symmetry of the radiation lobes; the first metal feeding microstrip line and the second metal feeding microstrip line respectively perform single-ended excitation on the second metal microstrip open-loop resonator and the fourth metal microstrip open-loop resonator, so the open-loop resonators also have the function of balun transformation.

[0022] The dual-band antenna is both a radiation element, a duplex synthesis element, and a frequency-selective resonance element of the channel filter, making the structure of the present invention compact.

[0023] Furthermore, the signal of one channel is differentially fed to the dual-band antenna through the first metal feeding microstrip line, the second metal microstrip open-loop resonator, and the first metal microstrip open-loop resonator, and radiated through the metal rectangular radiation patch. Due to the suppression of the other channel filter formed by the third metal microstrip open-loop resonator and the fourth metal microstrip open-loop resonator, the signal cannot leak into the channel connected to the second metal feeding microstrip line, realizing channel isolation.

[0024] The signal of the other channel is differentially fed to the dual-band antenna through the second metal feeding microstrip line, the fourth metal microstrip open-loop resonator, and the third metal microstrip open-loop resonator, and radiated through the metal rectangular radiation patch. Due to the suppression of the channel filter formed by the second metal microstrip open-loop resonator and the first metal microstrip open-loop resonator, the signal cannot leak into the channel connected to the first metal feeding microstrip line, realizing channel isolation.

[0025] The present invention realizes radiation, duplex synthesis, channel filtering, differential feeding, and balun transformation functions simultaneously with a compact structure, ensuring good cross-polarization performance, lobe symmetry, and duplex filtering and radiation capabilities.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention adopts a combined design of a filtering circuit and a duplex antenna, so there is no need for an extra matching circuit. Moreover, since the substrates of the antenna are integrated together, the filtering antenna has the advantages of high integration, small size, and light weight.

[0028] 2. The duplex filtering antenna provided by the present invention has a better bandwidth broadening; and this antenna can be used as a basic unit of the antenna for arraying, having great research space.

[0029] 3. The duplex antenna provided by the present invention adopts a symmetric dual-port input structure, which can achieve symmetric radiation and low cross polarization. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the overall schematic diagram of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention.

[0031] Figure 2 is the overall size schematic diagram of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention.

[0032] Figure 3 is the side view of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention.

[0033] Figure 4 is the specific size schematic diagram of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention.

[0034] Figure 5 is the curve graph of the S-parameter simulation result of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention.

[0035] Figure 6 is the curve graph of the far-field gain of the vertical antenna center varying with frequency of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention.

[0036] Figure 7 is the far-field pattern of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention at f = 2 GHz and Φ = 0°.

[0037] Figure 8 is the far-field pattern of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention at f = 2.45 GHz and Φ = 0°.

[0038] Figure 9 is the far-field pattern of a differential duplex filtering antenna with double-slot symmetric excitation in an embodiment of the present invention at f = 2 GHz and Φ = 90°.

[0039] Figure 10It is the far - field pattern of a differential duplex filtering antenna with dual - slot symmetric excitation at Φ = 90° when f = 2.45 GHz in the embodiment of the present invention.

[0040] In the figure, there are upper - layer dielectric substrate 1, lower - layer dielectric substrate 2, metal floor 3, rectangular metal radiation patch 4, first metal feeding microstrip line 5, coupling slot 6, metal microstrip resonator 7, first metal microstrip split - ring resonator 8, second metal microstrip split - ring resonator 9, third metal microstrip split - ring resonator 10, fourth metal microstrip split - ring resonator 11, and second metal feeding microstrip line 12. Detailed implementation mode

[0041] The following further describes the specific implementation of the present invention in detail in combination with embodiments and drawings, but the implementation manners of the present invention are not limited thereto.

[0042] Embodiment:

[0043] As Figure 1 and Figure 2 shown, a differential duplex filtering antenna with dual - slot symmetric excitation includes upper - layer dielectric substrate 1, lower - layer dielectric substrate 2, metal floor 3, first metal feeding microstrip line 5, second metal feeding microstrip line 12, metal rectangular radiation patch 4, coupling slot 6, metal microstrip resonator 7, and first metal microstrip split - ring resonator 8, second metal microstrip split - ring resonator 9, third metal microstrip split - ring resonator 10, fourth metal microstrip split - ring resonator 11;

[0044] The upper - layer dielectric substrate 1, metal floor 3, and lower - layer dielectric substrate 2 are bonded together, and the metal floor 3 is embedded between the upper - layer dielectric substrate 1 and the lower - layer dielectric substrate 2; two parallel - placed coupling slots 6 are engraved on the metal floor 3;

[0045] The metal rectangular radiation patch 4 is attached to the upper surface of the upper - layer dielectric substrate 1, and the center of the metal rectangular radiation patch 4 coincides with the center of the upper - layer dielectric substrate 1. Its length is half of the waveguide wavelength, and its width is greater than the distance between the two coupling slots 6;

[0046] The first metal feeding microstrip line 5, the second metal feeding microstrip line 12, the metal microstrip resonator 7, and the first metal microstrip split ring resonator 8, the second metal microstrip split ring resonator 9, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11 are attached to the lower surface of the lower dielectric substrate 2; among them, along the central axis of the lower dielectric substrate 2 from one side to the other side of its lower surface, they are arranged in sequence as the second metal microstrip split ring resonator 9, the first metal microstrip split ring resonator 8, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11; the metal microstrip resonator 7 passes through the center of the lower surface of the lower dielectric substrate 2 and is located between the first metal microstrip split ring resonator 8 and the third metal microstrip split ring resonator 10; the first metal feeding microstrip line 5 and the second metal feeding microstrip line 12 are respectively connected to the second metal microstrip split ring resonator 9 and the fourth metal microstrip split ring resonator 11.

[0047] The upper dielectric substrate 1, the lower dielectric substrate 2, the metal ground 3, the metal rectangular radiation patch 4, the coupling slot 6, the metal microstrip resonator 7, and the first metal microstrip split ring resonator 8, the second metal microstrip split ring resonator 9, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11 all have a symmetric structure, and their symmetry planes coincide.

[0048] Two coupling slots 6 are symmetrically distributed on both sides of the common symmetry plane of the upper dielectric substrate 1, the lower dielectric substrate 2, the metal ground 3, the metal rectangular radiation patch 4, the coupling slot 6, the metal microstrip resonator 7, and the first metal microstrip split ring resonator 8, the second metal microstrip split ring resonator 9, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11; the distance between the two coupling slots 6 is larger than the widths of the first metal microstrip split ring resonator 8, the second metal microstrip split ring resonator 9, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11, and is shorter than the length of the metal microstrip resonator 7.

[0049] The filtering feeding structure is as Figure 4 shown. The metal microstrip resonator 7 is a metal strip passing through the center of the lower surface of the lower dielectric substrate 2 and is perpendicular to the common symmetry plane of the upper dielectric substrate 1, the lower dielectric substrate 2, the metal ground 3, the metal rectangular radiation patch 4, the coupling slot 6, and the first metal microstrip split ring resonator 8, the second metal microstrip split ring resonator 9, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11.

[0050] The first metal microstrip split ring resonator 8, the second metal microstrip split ring resonator 9, the third metal microstrip split ring resonator 10, and the fourth metal microstrip split ring resonator 11 are all rectangular rings surrounded by microstrip lines, and there is an opening in the middle of one side of the rectangular ring.

[0051] The first metal microstrip split-ring resonator 8 and the third metal microstrip split-ring resonator 10 are respectively distributed on both sides of the metal microstrip resonator 7, and the side of the rectangular ring parallel to the side with an opening is close to and parallel to the metal microstrip resonator 7.

[0052] The side with an opening in the second metal microstrip split-ring resonator 9 is close to and parallel to the side with an opening in the first metal microstrip split-ring resonator 8; the side with an opening in the fourth metal microstrip split-ring resonator 11 is close to and parallel to the side with an opening in the third metal microstrip split-ring resonator 10.

[0053] The second metal microstrip split-ring resonator 9 is fed through the first metal feeding microstrip line 5; the fourth metal microstrip split-ring resonator 11 is fed through the second metal feeding microstrip line 12.

[0054] One end of the first metal feeding microstrip line 5 can be connected to any side of the second metal microstrip split-ring resonator 9, and the other end is connected to a feeding signal source; one end of the second metal feeding microstrip line 12 can be connected to any side of the fourth metal microstrip split-ring resonator 11, and the other end is connected to a feeding signal source.

[0055] As Figure 3 and Figure 4 shown, in this embodiment, the upper and lower dielectric substrates are both Rogers4003c, with a relative dielectric constant of 3.55. The thicknesses h1 and h2 of the two plates are 5 mm and 0.5 mm respectively, and the remaining parameters l, l1, l2, l3, l4, l5, l6, l7, l8, l9, l 10 、l s 、w、w1、w2、w s 、s1、s2、s3、s4 are 80 mm, 40 mm, 8 mm, 12.225 mm, 0.125 mm, 11.5 mm, 32 mm, 11 mm, 2 mm, 9.6 mm, 0.5 mm, 20 mm, 80 mm, 29 mm, 1.1 mm, 0.8 mm, 0.28 mm, 1 mm, 0.3 mm, 0.3 mm respectively; the size of the entire antenna is 80×80×5.5 mm 3 。

[0056] The upper dielectric substrate 1, the metal ground plane 3, and the metal rectangular radiation patch 4 form a microstrip antenna. The metal microstrip resonator 7 is mutually coupled with the microstrip antenna through the coupling slot 6 to form a dual - frequency antenna, resonating at two operating frequencies, namely the transmitting frequency and the receiving frequency. Due to the symmetry of the structure, that is, the upper dielectric substrate 1, the metal ground plane 3, the metal rectangular radiation patch 4, the metal microstrip resonator 7, and the coupling slot 6 have a common symmetry plane. At the transmitting frequency and the receiving frequency, the field distribution on the dual - frequency antenna is symmetric about the symmetry plane, forming a dual - frequency differential antenna. Therefore, the radiation lobes are symmetric and have an inhibitory effect on cross - polarization.

[0057] The metal microstrip resonator 7 also functions to synthesize two signals, thus forming a duplex antenna. The first metal microstrip open - loop resonator 8 and the second metal microstrip open - loop resonator 9 resonate at one resonance frequency of the dual - frequency antenna, and form a filter for one channel with this resonance mode of the dual - frequency antenna. The third metal microstrip open - loop resonator 10 and the fourth metal microstrip open - loop resonator 11 resonate at the other resonance frequency of the dual - frequency antenna, and form a filter for the other channel with this resonance mode of the dual - frequency antenna, enabling both channels of the duplex antenna to have filtering characteristics, thus forming a filtering antenna. Since the first metal microstrip open - loop resonator 8, the second metal microstrip open - loop resonator 9, the third metal microstrip open - loop resonator 10, and the fourth metal microstrip open - loop resonator 11 all have symmetric structures and the same symmetry plane as the dual - frequency antenna, both channel filters are differential filters, ensuring the differential excitation of the dual - frequency antenna, and thus ensuring good cross - polarization performance and the symmetry of the radiation lobes. The first metal feed microstrip line 5 and the second metal feed microstrip line 12 perform single - ended excitation on the second metal microstrip open - loop resonator 9 and the fourth metal microstrip open - loop resonator 11 respectively. Therefore, the open - loop resonators 9 and 11 simultaneously have the function of balanced - unbalanced transformation.

[0058] The dual - frequency antenna is both a radiation unit, a duplex synthesis unit, and a frequency - selection resonance unit of the channel filter, making the structure of the present invention compact.

[0059] The signal of one channel is differentially fed to the dual - frequency antenna through the first metal feed microstrip line 5, the second metal microstrip open - loop resonator 9, and the first metal microstrip open - loop resonator 8, and radiated through the metal rectangular radiation patch 4. Due to the inhibitory effect of the other channel filter formed by the third metal microstrip open - loop resonator 10 and the fourth metal microstrip open - loop resonator 11, the signal cannot leak into the channel connected to the second metal feed microstrip line 12, realizing channel isolation.

[0060] The signal of another channel performs differential feeding on the dual-band antenna through the second metal feeding microstrip line 12, the fourth metal microstrip split-ring resonator 11, and the third metal microstrip split-ring resonator 10, and radiates through the metal rectangular radiation patch 4. Due to the suppression of the channel filter formed by the second metal microstrip split-ring resonator 9 and the first metal microstrip split-ring resonator 8, the signal cannot leak into the channel connected to the first metal feeding microstrip line 5, realizing channel isolation.

[0061] In this embodiment, the working center frequencies of the antenna are f = 2 GHz and f = 2.45 GHz respectively, and the bandwidths are Δf = 102 MHz and Δf = 129 MHz respectively. The S parameters of the antenna are as Figure 5 shown. The antenna has a relatively wide bandwidth. In the two working frequency bands, the maximum gains of the antenna are 5.26 dBi and 6.36 dBi at the center of the vertical antenna. The curves of the gain of the antenna in the z-axis direction changing with frequency are as Figure 6 shown. The cross polarizations are 40 dBi and 42 dBi respectively. The antenna has a low cross polarization. The radiation patterns of the antenna in the Φ = 0° plane xoz plane at f = 2 GHz and 2.45 GHz are as Figure 7 and 8 shown; the radiation patterns of the antenna in the Φ = 90° plane yoz plane at f = 2 GHz and f = 2.45 GHz are as Figure 9 and 10 shown; the antenna has the characteristic of symmetric radiation.

[0062] It can be seen from the above description that the differential duplex filtering antenna with dual-slot symmetric excitation of the present invention has a high integration degree, a small size, does not require an additional matching network, and has a good bandwidth broadening of the band-pass filter; because the antenna adopts a symmetric dual-port input structure, symmetric radiation and low cross polarization can be realized.

[0063] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A differential duplex filtering antenna with dual-slot symmetric excitation, characterized in that It includes an upper dielectric substrate (1), a lower dielectric substrate (2), a metal floor (3), a first metal feeding microstrip line (5), a second metal feeding microstrip line (12), a metal rectangular radiation patch (4), a coupling slot (6), a metal microstrip resonator (7), and a first metal microstrip split-ring resonator (8), a second metal microstrip split-ring resonator (9), a third metal microstrip split-ring resonator (10), and a fourth metal microstrip split-ring resonator (11); The upper dielectric substrate (1), the metal floor (3), and the lower dielectric substrate (2) are bonded together, and the metal floor (3) is embedded between the upper dielectric substrate (1) and the lower dielectric substrate (2); two parallel coupling slots (6) are engraved on the metal floor (3); The metal rectangular radiation patch (4) is attached to the upper surface of the upper dielectric substrate (1), and the center of the metal rectangular radiation patch (4) coincides with the center of the upper dielectric substrate (1). Its length is half of the waveguide wavelength, and its width is greater than the distance between the two coupling slots (6); The first metal feed microstrip line (5), the second metal feed microstrip line (12), the metal microstrip resonator (7), and the first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11) are attached to the lower surface of the lower dielectric substrate (2); among them, the second metal microstrip split-ring resonator (9), the first metal microstrip split-ring resonator (8), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11) are arranged in sequence from one side to the other side of the lower surface along the central axis of the lower dielectric substrate (2); the metal microstrip resonator (7) passes through the center of the lower surface of the lower dielectric substrate (2) and is located between the first metal microstrip split-ring resonator (8) and the third metal microstrip split-ring resonator (10); the first metal feed microstrip line (5) and the second metal feed microstrip line (12) are respectively connected to the second metal microstrip split-ring resonator (9) and the fourth metal microstrip split-ring resonator (11); the two coupling slots (6) are symmetrically distributed on both sides of the common symmetry plane of the upper dielectric substrate (1), the lower dielectric substrate (2), the metal floor (3), the metal rectangular radiation patch (4), the coupling slot (6), the metal microstrip resonator (7), and the first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11); the distance between the two coupling slots (6) is larger than the widths of the first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11), and is shorter than the length of the metal microstrip resonator (7); the upper dielectric substrate (1), the lower dielectric substrate (2), the metal floor (3), the metal rectangular radiation patch (4), the coupling slot (6), the metal microstrip resonator (7), and the first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11) all have a symmetric structure, and the symmetry planes coincide.

2. The differential duplex filtering antenna with dual-slot symmetric excitation according to claim 1, wherein The metal microstrip resonator (7) is a metal strip passing through the center of the lower surface of the lower dielectric substrate (2) and perpendicular to the common symmetry plane of the upper dielectric substrate (1), the lower dielectric substrate (2), the metal floor (3), the metal rectangular radiation patch (4), the coupling slot (6), and the first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11).

3. A differential duplex filtering antenna with dual-slot symmetric excitation according to claim 1, characterized in that The first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11) are all rectangular rings surrounded by microstrip lines, and there is an opening in the middle of one side of the rectangular ring.

4. The differential duplex filtering antenna with dual-slot symmetric excitation according to claim 3, characterized in that, The first metal microstrip split-ring resonator (8) and the third metal microstrip split-ring resonator (10) are respectively distributed on both sides of the metal microstrip resonator (7), and the side of the rectangular ring parallel to the side with an opening is close to and parallel to the metal microstrip resonator (7). The side with an opening in the second metal microstrip split-ring resonator (9) is close to and parallel to the side with an opening in the first metal microstrip split-ring resonator (8); the side with an opening in the fourth metal microstrip split-ring resonator (11) is close to and parallel to the side with an opening in the third metal microstrip split-ring resonator (10).

5. A differential duplex filtering antenna with dual-slot symmetric excitation according to claim 1, wherein The second metal microstrip split-ring resonator (9) is fed through the first metal feed microstrip line (5). The fourth metal microstrip split-ring resonator (11) is fed through the second metal feed microstrip line (12). One end of the first metal feed microstrip line (5) can be connected to any side of the second metal microstrip split-ring resonator (9), and the other end is connected to a feed signal source; one end of the second metal feed microstrip line (12) can be connected to any side of the fourth metal microstrip split-ring resonator (11), and the other end is connected to a feed signal source.

6. The differential duplex filtering antenna with dual-slot symmetric excitation according to claim 1, characterized in that The upper dielectric substrate (1), the metal floor (3), and the metal rectangular radiation patch (4) form a microstrip antenna. The metal microstrip resonator (7) is mutually coupled with the microstrip antenna through the coupling slot (6) to form a dual-band antenna, which resonates at two operating frequencies, namely the transmitting frequency and the receiving frequency. Due to the symmetry of the structure, that is, the upper dielectric substrate (1), the metal floor (3), the metal rectangular radiation patch (4), the metal microstrip resonator (7), and the coupling slot (6) have a common symmetry plane. At the transmitting frequency and the receiving frequency, the field distribution on the dual-band antenna is symmetric about the symmetry plane, forming a dual-band differential antenna. Therefore, the radiation lobes are symmetric and have an inhibitory effect on cross polarization.

7. A differential duplex filtering antenna with dual-slot symmetric excitation according to claim 1, characterized in that The metal microstrip resonator (7) also serves to synthesize two signals, thus forming a duplex antenna; the first metal microstrip split-ring resonator (8) and the second metal microstrip split-ring resonator (9) resonate at one resonance frequency of the dual-band antenna, and together with this resonance mode of the dual-band antenna, they form a filter for one channel. The third metal microstrip split-ring resonator (10) and the fourth metal microstrip split-ring resonator (11) resonate at the other resonance frequency of the dual-band antenna, and together with this resonance mode of the dual-band antenna, they form a filter for the other channel, enabling both channels of the duplex antenna to have filtering characteristics, thus forming a filtering antenna; since the first metal microstrip split-ring resonator (8), the second metal microstrip split-ring resonator (9), the third metal microstrip split-ring resonator (10), and the fourth metal microstrip split-ring resonator (11) all have a symmetric structure and the same symmetry plane as the dual-band antenna, both channel filters are differential filters. The first metal feed microstrip line (5) and the second metal feed microstrip line (12) respectively perform single-ended excitation on the second metal microstrip open-loop resonator (9) and the fourth metal microstrip open-loop resonator (11). Therefore, the second metal microstrip open-loop resonator (9) and the fourth metal microstrip open-loop resonator (11) simultaneously have the function of balanced-unbalanced transformation.

8. The differential duplex filtering antenna with dual-slot symmetric excitation according to claim 7, characterized in that, The signal of one channel performs differential feeding on the dual-frequency antenna through the first metal feed microstrip line (5), the second metal microstrip open-loop resonator (9), and the first metal microstrip open-loop resonator (8), and is radiated through the metal rectangular radiation patch (4). Due to the suppression of the other channel filter formed by the third metal microstrip open-loop resonator (10) and the fourth metal microstrip open-loop resonator (11), the signal cannot leak into the channel connected to the second metal feed microstrip line (12), achieving channel isolation. The signal of the other channel performs differential feeding on the dual-frequency antenna through the second metal feed microstrip line (12), the fourth metal microstrip open-loop resonator (11), and the third metal microstrip open-loop resonator (10), and is radiated through the metal rectangular radiation patch (4). Due to the suppression of the channel filter formed by the second metal microstrip open-loop resonator (9) and the first metal microstrip open-loop resonator (8), the signal cannot leak into the channel connected to the first metal feed microstrip line (5), achieving channel isolation.

Images