A frequency-tunable decoupling patch antenna array

Abstract

The application discloses a frequency-adjustable decoupling patch antenna array, which comprises frequency-adjustable patch antenna units, an adjustable open-circuit microstrip decoupling structure and a microstrip line-slot coupling feeding structure, wherein the adjustable open-circuit microstrip decoupling structure is arranged between the frequency-adjustable patch antenna units, the adjustable open-circuit microstrip decoupling structure utilizes the adjustment capability of a variable capacitance diode Cv1 on the antenna operating frequency and the differential mode impedance of the array, and the following effect of the variable capacitance diode Cv2 on the common mode impedance of the array following the differential mode impedance when frequency modulation, and the cross-polarization suppression effect of the microstrip line-slot coupling structure are combined, so that the frequency-continuously-adjustable decoupling patch antenna array is realized, and the decoupling depth, the adjustable bandwidth and the bandwidth in a single state can be considered.

Description

Technical Field

[0001] This invention relates to a wireless communication device, and more particularly to a decoupled patch antenna array. Background Technology

[0002] Frequency-tunable patch antenna elements, through voltage regulation, enable the antenna to operate in different frequency bands, increasing channel capacity and improving spectral efficiency. However, assembling these frequency-tunable patch antenna elements at a certain spacing results in varying electrical spacing at different operating frequencies, leading to unstable mutual coupling, deterioration of active matching, and reduced radiation efficiency. Unlike traditional decoupled patch antenna arrays, whose matching and decoupling can only operate in fixed frequency bands, frequency-tunable decoupled patch antenna arrays achieve frequency tuning and adjustable mutual coupling null-following to adapt to different operating frequency bands. Therefore, it is necessary to propose a frequency-tunable decoupled patch antenna array.

[0003] There is only one existing frequency-tunable decoupling patch antenna array, which achieves decoupling through mode superposition and controls the slot length by switching PIN diodes. However, it suffers from shallow decoupling depth, narrow adjustable bandwidth, narrow bandwidth in a single state, and lack of support for continuous adjustment. Other frequency-tunable decoupling patch antennas are duplex types, not array antennas. They are essentially single-patch antennas with slots on the left, right, and middle sides of the patch, and varactor diodes loaded to achieve electromagnetic cancellation decoupling in frequency-tunable mode. However, they also suffer from shallow decoupling depth and narrow bandwidth in a single state. Therefore, it is necessary to propose a frequency-tunable decoupling patch antenna array that balances decoupling depth, adjustable bandwidth, bandwidth in a single state, and continuous adjustability. Summary of the Invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a frequency-tunable decoupled patch antenna array is proposed, which can take into account decoupling depth, adjustable bandwidth, bandwidth in a single state, and continuous adjustability.

[0005] Technical solution: A frequency-tunable decoupled patch antenna array, comprising, from top to bottom, a top layer structure, an upper dielectric substrate, a middle metal structure, a lower dielectric substrate, and a bottom metal structure;

[0006] The top-level structure includes four small rectangular metal patches, two large rectangular metal patches, two short metal strips, and one long metal strip on the surface of the upper dielectric substrate. The long metal strip is vertically arranged, and the two large rectangular metal patches are symmetrically arranged about the long metal strip. A small rectangular metal patch is arranged on the top and bottom sides of each large rectangular metal patch, and the small rectangular metal patches are connected to the large rectangular metal patches through a first varactor diode. The two short metal strips are respectively arranged at the top and bottom ends of the long metal strip, and one end of each short metal strip is connected to the adjacent end of the long metal strip through a second varactor diode. DC bias stubs are connected to the middle of the long metal strip and the other ends of the two short metal strips. DC bias stubs are also connected to the sides of the large rectangular metal patches and to each of the small rectangular metal patches.

[0007] The intermediate metal structure is a metal ground with two horizontal rectangular slots on the upper surface of the lower dielectric substrate. The two rectangular slots are located directly below the horizontal center lines of the two large rectangular metal patches. There is an air layer between the intermediate metal structure and the upper dielectric substrate. One end of each small rectangular metal patch and each short metal strip is connected to the metal ground through a metal post.

[0008] The underlying metal structure includes two metal strips disposed on the lower surface of the underlying dielectric substrate and orthogonally arranged to the two rectangular slots.

[0009] Furthermore, two small rectangular metal patches, one large rectangular metal patch, and their connected three DC bias stubs, two first varactor diodes, along with the upper dielectric substrate and metal ground, together form a frequency-tunable patch antenna unit; two short metal strips, one long metal strip, and their connected three DC bias stubs, two second varactor diodes, along with the upper dielectric substrate and metal ground, together form an adjustable open-circuit microstrip decoupling structure; a metal ground with two rectangular slots, a lower dielectric substrate, and metal strips form a microstrip line-slot coupled feeding structure; in the frequency-tunable patch antenna unit, the antenna operating frequency and array differential-mode impedance are adjusted by adjusting the first varactor diodes; in the adjustable open-circuit microstrip decoupling structure, the common-mode impedance of the array is adjusted by adjusting the second varactor diodes, and the differential-mode impedance is followed during frequency modulation, achieving mutual coupling zero-point following the trend of the antenna operating frequency change, thus achieving decoupling when the frequency is adjustable.

[0010] Furthermore, the DC bias stubs connected by the large rectangular metal patch and the long metal strip are each composed of a feed patch, a resistor, a short metal strip, and an inductor connected in sequence; the DC bias stubs connected by the small rectangular metal patch and the short metal strip are each composed of a ground patch, inductor one, a short metal strip, and inductor two connected in sequence.

[0011] Furthermore, the vertical length of the small rectangular metal patch is between 0.05λ0 and 0.09λ0, and the vertical length of the large rectangular metal patch is between 0.22λ0 and 0.18λ0; the length of the long metal strip is between 0.23λ0 and 0.27λ0, and the length of the short metal strip is between 0.03λ0 and 0.07λ0, where λ0 is the free space wavelength corresponding to the center frequency.

[0012] Furthermore, the length of the rectangular groove is between 0.22λ0 and 0.26λ0; the thickness of the air layer between the intermediate metal structure and the upper dielectric substrate is between 0.04λ0 and 0.08λ0.

[0013] Furthermore, one end of the metal strip is flush with the metal edge, and the other end extends beyond the rectangular groove by a length between 0.05λ0 and 0.09λ0.

[0014] Beneficial effects: Existing frequency-tunable decoupled antenna arrays can only achieve a shallow decoupling depth and suffer from narrow adjustable bandwidth, narrow bandwidth in a single state, and lack of support for continuous adjustment. This invention places an adjustable open-circuit microstrip decoupling structure between frequency-tunable patch antenna elements. Utilizing the first varactor diode's ability to adjust the antenna operating frequency and array differential-mode impedance, and the second varactor diode's ability to follow the array's common-mode impedance to differential-mode impedance during frequency modulation, combined with the cross-polarization suppression effect of the microstrip line-slot coupling structure, a continuously frequency-tunable decoupled patch antenna array is achieved, while simultaneously considering decoupling depth, adjustable bandwidth, and bandwidth in a single state.

[0015] Specifically, in the adjustable open-circuit microstrip decoupling structure, the short metal strip and the long metal strip are connected through the second varactor diode, and DC bias stubs are loaded at both ends and in the middle. The overall structure is located between the frequency-adjustable patch antenna elements. By utilizing the following effect of the second varactor diode on the common-mode impedance to differential-mode impedance of the array during frequency modulation, the mutual coupling zero point follows the changing trend of the working frequency, thus achieving decoupling when the frequency is adjustable.

[0016] In the frequency-tunable patch antenna unit, large and small rectangular metal patches are connected by a first varactor diode. DC bias stubs are added at both ends and in the middle. The operating frequency can be continuously adjusted by the ability of the first varactor diode to adjust the antenna operating frequency and the differential mode impedance of the array.

[0017] The microstrip line-slot coupled feed structure consists of a microstrip feed line and a rectangular slot orthogonally. The rectangular slot is located at the center directly below the large rectangular metal patch. It can suppress the horizontal current on the metal ground when the frequency is adjusted, reduce the cross polarization of the antenna when the frequency is adjustable, and avoid the deterioration of the overall cross polarization of the FM antenna. Attached Figure Description

[0018] Figure 1This is a schematic cross-sectional view of the frequency-tunable coupled patch antenna array of the present invention.

[0019] Figure 2 This is a top-view structural diagram of the frequency-tunable coupled patch antenna array of the present invention;

[0020] Figure 3 This is a top view of the intermediate layer structure of the frequency-tunable coupled patch antenna array of the present invention;

[0021] Figure 4 This is a bottom-view structural diagram of the frequency-tunable coupled patch antenna array of the present invention;

[0022] Figure 5 The three states of the present invention S Parameter simulation results;

[0023] Figure 6 The center frequency in state one of the embodiments of the present invention. E Face and H Surface simulation radiation pattern;

[0024] Figure 7 The center frequency in state two of this embodiment of the invention. E Face and H Surface simulation radiation pattern;

[0025] Figure 8 The center frequency of the embodiment of the present invention in state three. E Face and H Surface simulation radiation pattern. Detailed Implementation

[0026] The invention will now be further explained with reference to the accompanying drawings.

[0027] like Figure 1 As shown, a frequency-tunable decoupled patch antenna array mainly consists of a top layer structure 1, an upper dielectric substrate 2, a middle metal structure 3, a lower dielectric substrate 4, a bottom metal structure 5, and metal pillars 6.

[0028] like Figure 2 As shown, the top layer structure 1 includes four small rectangular metal patches 101, two large rectangular metal patches 102, two short metal strips 103, one long metal strip 104, one DC bias stub 105, one DC bias stub 106, four DC bias stubs 107, two DC bias stubs 108, four varactor diodes Cv1, and two varactor diodes Cv2 located on the surface of the upper dielectric substrate 2.

[0029] A long metal strip 104 is vertically positioned, and two large rectangular metal patches 102 are symmetrically arranged about the left and right sides of the long metal strip 104. The inner side of each large rectangular metal patch 102 is connected to a DC bias stub 105. A small rectangular metal patch 101 is positioned on the top and bottom sides of each large rectangular metal patch 102, and the opposite sides of the small rectangular metal patch 101 and the large rectangular metal patch 102 are connected by a varactor diode Cv1. Another parallel side of the small rectangular metal patch 101 and the large rectangular metal patch 102 is connected to a DC bias stub 107.

[0030] Two short metal strips 103 are vertically positioned at the top and bottom of a long metal strip 104, respectively. One end of each short metal strip 103 is connected to the adjacent end of the long metal strip 104 via a varactor diode Cv2, and the other end of each short metal strip 103 is connected to a DC bias stub 108. A DC bias stub 106 is connected to the middle of the side of the long metal strip 104.

[0031] The DC bias stub 105 consists of a surface mount chip, a resistor, a short metal strip, and an inductor connected in sequence, with one end of the inductor connected to the inner side of the large rectangular metal surface mount chip 102. The DC bias stub 106 consists of a surface mount chip, a resistor, a short metal strip, and an inductor connected in sequence, with one end of the inductor connected to the side of the long metal strip 104. The DC bias stub 107 consists of a surface mount chip, inductor one, a short metal strip, and inductor two connected in sequence, with one end of inductor two connected to the top or bottom edge of the small rectangular metal surface mount chip 101. The DC bias stub 108 consists of a surface mount chip, inductor one, a short metal strip, and inductor two connected in sequence, with one end of inductor two connected to one end of the short metal strip 103.

[0032] The vertical length of the small rectangular metal patch 101 is between 0.05λ0 and 0.09λ0, and the vertical length of the large rectangular metal patch 102 is between 0.22λ0 and 0.18λ0; the length of the long metal strip 104 is between 0.23λ0 and 0.27λ0, and the length of the short metal strip 103 is between 0.03λ0 and 0.07λ0, where λ0 is the free space wavelength corresponding to the center frequency.

[0033] like Figure 3 As shown, the intermediate metal structure 3 is a metal ground 301 with two horizontal rectangular slots 302 disposed on the upper surface of the lower dielectric substrate 4. The two rectangular slots 302 are located directly below the horizontal center lines of the two large rectangular metal patches 102. The length of the rectangular slots 302 is between 0.22λ0 and 0.26λ0. There is an air layer with a thickness between 0.04λ0 and 0.08λ0 between the intermediate metal structure 3 and the upper dielectric substrate 2. The patches of DC bias stubs 107 and 108 are connected to the metal ground 301 through metal pillars 6.

[0034] like Figure 4 As shown, the bottom metal structure 5 consists of two metal strips 501 disposed on the lower surface of the lower dielectric substrate 4. The metal strips 501 are respectively positioned opposite the vertical line of the rectangular groove 302. One end of the metal strip 501 is flush with the bottom edge of the metal ground 301, and the length of the other end extending beyond the rectangular groove 302 is between 0.05λ0 and 0.09λ0.

[0035] In the above structure, the small rectangular metal patch 101, the large rectangular metal patch 102, the DC bias stub 105, the DC bias stub 107, the varactor diode Cv1, the upper dielectric substrate 2, the metal ground 301, and the metal pillar 6 form two frequency-tunable patch antenna elements. The short metal strip 103, the long metal strip 104, the DC bias stub 106, the DC bias stub 108, the varactor diode Cv2, the upper dielectric substrate 2, the metal ground 301, and the metal pillar 6 form an adjustable open-circuit microstrip decoupling structure. The metal ground 301 with two rectangular slots 302, the lower dielectric substrate 4, and the metal strip 501 form a microstrip line-slot coupled feeding structure.

[0036] In this invention, the signal is fed in through a microstrip line-slot coupled feeding structure. Under the action of the dual-element frequency-tunable patch antenna and the adjustable open-circuit microstrip decoupling structure between the dual elements, a frequency-tunable coupled patch antenna array with mutual coupling zero-point following is realized.

[0037] The DC signal is input through the DC feed patch of DC bias stub 105 and DC bias stub 106, and output from the short-circuited metal patch of DC bias stub 107 and DC bias stub 108. The capacitance values ​​of varactor diodes Cv1 and Cv2 can be controlled by voltage, thus providing a basis for realizing a frequency-continuously adjustable coupled patch antenna array.

[0038] In this process, the varactor diode Cv2 in the adjustable open-circuit microstrip decoupling structure can adjust the common-mode impedance of the patch antenna array, while the varactor diode Cv1 in the frequency-tunable patch antenna is used to adjust the antenna's operating frequency. The current on the patch remains in the same direction vertically and exhibits a characteristic of first converging and then dispersing at Cv1. The current in the adjustable open-circuit microstrip decoupling structure always maintains an opposite state to the patch current. When Cv1 increases, the antenna's operating frequency decreases, and the real part of the differential-mode impedance decreases while the imaginary part concentrates in the inductive region. At this time, adjusting Cv2 can bring the common-mode impedance closer to the differential-mode impedance in the high-frequency state, and further increasing Cv2 can make the common-mode impedance during frequency modulation follow the changes in the differential-mode impedance during frequency modulation.

[0039] Therefore, under the adjustment of Cv1 and Cv2, the mutual coupling nulls can follow the change when the operating frequency shifts, resulting in a frequency-continuously adjustable tunable patch antenna array with good decoupling depth. The layer distribution structure of this invention can balance tunable bandwidth and bandwidth in a single state. Using a microstrip line-slot coupling structure as the antenna's feed structure can significantly reduce the antenna's cross-polarization when the frequency is adjustable, avoiding the deterioration of the overall cross-polarization of the FM antenna.

[0040] The substrate used in this embodiment is Rogers RO4003C, the varactor diode is SMV2020-079LF, and the array size is 0.96λ0 × 0.13λ0 × 0.09λ0. The vertical length of the small rectangular metal patch 101 is 0.07λ0, and the vertical length of the large rectangular metal patch 102 is 0.20λ0; the length of the long metal strip 104 is 0.25λ0, the length of the short metal strip 103 is 0.05λ0, the length of the rectangular groove 302 is 0.24λ0, and the air layer thickness between the intermediate metal structure 3 and the upper dielectric substrate 2 is 0.06λ0.

[0041] Figure 5 The simulation under three states in this embodiment is listed. S The parameter response curves show three states: State 1: Cv1=0.15 pF, Cv2=0.25 pF; State 2: Cv1=0.5 pF, Cv2=0.6 pF; State 3: Cv1=0.9 pF, Cv2=1.3 pF. The corresponding matching frequency ranges for these three states are 4.51 GHz ~ 4.87 GHz, 4.17 GHz ~ 4.48 GHz, and 3.97 GHz ~ 4.25 GHz, respectively; that is, the relative bandwidths are 7.67%, 7.17%, and 6.81%, respectively. The total relative matching frequency range covered by the three states is 13.2%. Simultaneously, the mutual coupling follows the matching movement, and the coupling remains below -18.5 dB during the overall frequency adjustment process.

[0042] Figures 6 to 8 For the above three states E noodle, H Surface orientation diagram, E The beamwidth is between 66.5° and 70°. H The beamwidth is between 84.8° and 100.1°, and the cross-polarization level is below -18.7 dB in all three states.

[0043] Compared with existing technologies, the frequency-adjustable decoupling patch antenna array of the present invention can take into account decoupling depth, adjustable bandwidth, bandwidth in a single state, and continuous adjustability.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A frequency-tunable decoupled patch antenna array, characterized in that, From top to bottom, it includes a top layer structure (1), an upper dielectric substrate (2), a middle layer metal structure (3), a lower dielectric substrate (4), and a bottom layer metal structure (5). The top layer structure (1) includes four small rectangular metal patches (101), two large rectangular metal patches (102), two short metal strips (103), and one long metal strip (104) located on the surface of the upper dielectric substrate (2). The two large rectangular metal patches (102) are symmetrical about the vertically arranged long metal strip (104). Each large rectangular metal patch (102) has a small rectangular metal patch (101) on its upper and lower sides. The small rectangular metal patches (101) and the large rectangular metal patches (102) are connected by a first varactor diode. The two short metal strips (103) are respectively located at the upper and lower ends of the long metal strip (104). One end of the short metal strip (103) is connected to the adjacent end of the long metal strip (104) through a second varactor diode. The middle part of the long metal strip (104) and the other end of the two short metal strips (103) are respectively connected to DC bias stubs. The sides of the large rectangular metal patch (102) and each of the small rectangular metal patches (101) are respectively connected to DC bias stubs; The intermediate metal structure (3) is a metal ground (301) with two horizontal rectangular slots (302) set on the upper surface of the lower dielectric substrate (4). The two rectangular slots (302) are located directly below the horizontal center line of the two large rectangular metal patches (102). There is an air layer between the intermediate metal structure (3) and the upper dielectric substrate (2). One end of the DC bias stubs connected to each small rectangular metal patch (101) and each metal strip (103) is connected to the metal ground (301) through metal pillars (6). The bottom metal structure (5) includes two metal strips (501) disposed on the lower surface of the lower dielectric substrate (4) and orthogonally disposed to the two rectangular grooves (302).

2. The frequency-tunable decoupled patch antenna array according to claim 1, characterized in that, Two small rectangular metal patches (101) on one side, one large rectangular metal patch (102) and their three DC bias stubs, two first varactor diodes, and the upper dielectric substrate (2) and metal ground (301) together form a frequency-tunable patch antenna unit. Two short metal strips (103), a long metal strip (104), and three DC bias stubs connected to them, two second varactor diodes, an upper dielectric substrate (2), and a metal ground (301) together form an adjustable open-circuit microstrip decoupling structure; a metal ground (301) with two rectangular slots (302), a lower dielectric substrate (4), and a metal strip (501) together form a microstrip line-slot coupled feeding structure; In the frequency-tunable patch antenna unit, the antenna operating frequency and array differential-mode impedance are adjusted by adjusting the first varactor diode; in the adjustable open-circuit microstrip decoupling structure, the common-mode impedance of the array is adjusted by adjusting the second varactor diode and the differential-mode impedance is followed during frequency modulation, so as to realize the mutual coupling zero point follows the change trend of the antenna operating frequency and achieve decoupling when the frequency is adjustable.

3. The frequency-tunable decoupled patch antenna array according to claim 1, characterized in that, The DC bias stubs connected by the large rectangular metal patch (102) and the long metal strip (104) are all composed of a feed patch, a resistor, a short metal strip and an inductor connected in sequence; the DC bias stubs connected by the small rectangular metal patch (101) and the short metal strip (103) are all composed of a ground patch, an inductor one, a short metal strip and an inductor two connected in sequence.

4. The frequency-tunable decoupled patch antenna array according to claim 1, characterized in that, The vertical length of the small rectangular metal patch (101) is between 0.05λ0 and 0.09λ0, and the vertical length of the large rectangular metal patch (102) is between 0.22λ0 and 0.18λ0; the length of the long metal strip (104) is between 0.23λ0 and 0.27λ0, and the length of the short metal strip (103) is between 0.03λ0 and 0.07λ0, where λ0 is the free space wavelength corresponding to the center frequency.

5. The frequency-tunable decoupled patch antenna array according to claim 4, characterized in that, The length of the rectangular groove (302) is between 0.22λ0 and 0.26λ0; the thickness of the air layer between the intermediate metal structure (3) and the upper dielectric substrate (2) is between 0.04λ0 and 0.08λ0.

6. The frequency-tunable decoupled patch antenna array according to claim 5, characterized in that, One end of the metal strip (501) is flush with the edge of the metal ground (301), and the other end extends beyond the rectangular groove (302) by a length between 0.05λ0 and 0.09λ0.

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