Frequency, polarization and directional diagram reconfigurable antenna unit and array

Abstract

The invention provides a frequency, polarization and directional diagram reconfigurable antenna unit and array. The antenna unit comprises a tuning microstrip antenna unit and a reconfigurable feed phase-shift network which are stacked, the tuning microstrip antenna unit comprises a circular radiation patch etched with a circular gap and four variable capacitance diodes bridged on the circular gap; two output ports of a Wilkinson power division network in the reconfigurable feed phase shift network are respectively connected with two feed point micro-strips through PIN diodes, and four feed points form a structure which is in space symmetry and asymmetric in impedance. The circular radiation patch and the annular radiation patch in the antenna unit have continuity in structure, only four variable capacitance diodes are loaded on the annular gap, gain fluctuation is reduced, and the antenna unit is fed through four feed points which are symmetrical in space and asymmetric in impedance, so that the antenna unit is more stable in performance. Good matching can be kept between the feed phase-shifting network and the antenna unit in a broadband range, and the tuning bandwidth of the antenna is widened.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas, and relates to a reconfigurable antenna unit and array, and specifically to a frequency, polarization, and directional pattern reconfigurable antenna and array, which can be used in fields such as wireless communications. Background Art

[0002] With the rapid development of wireless communication technology and the diversification of application scenarios, higher requirements are placed on antenna performance. Traditional antenna designs often have a single operating frequency, radiation direction or polarization mode, which is difficult to meet the current communication technology's multi-functional and multi-scenario application requirements. Reconfigurable antennas have become one of the hot topics in current antenna technology research because they can dynamically adjust the operating frequency, polarization mode or radiation direction. Frequency, polarization and direction Figure 3 Dimensionally cooperative reconfigurable antenna arrays can maximize the real-time switching of communication systems between multiple functions.

[0003] At present, most of the research on the three-parameter collaborative reconfiguration antenna array has a narrow frequency tuning bandwidth in design, poor pattern stability, and large fluctuations in antenna gain values, which are limited in practical application. For example, in 2021, Jun Hu disclosed a frequency, polarization, and pattern hybrid reconfigurable antenna array in the document "A Reconfigurable 1×4Circularly Polarized Patch Array Antenna With Frequency, Radiation Pattern, and Polarization Agility". The center of its radiating patch structure is a hexagonal patch, with six rectangular patches on each of the six sides, and a total of 6 varactor diodes are connected between the rectangular patches and the hexagonal patches. By adjusting the capacitance value of the varactor diodes between the hexagonal patch and the surrounding rectangular patches, the frequency adjustment and polarization reconstruction functions can be realized, and the pattern scanning function can be realized through the reconfigurable phase-shifted feeding network. The design can achieve five pattern reconstruction states within the adjustable frequency range, covering ±50°. However, since its reconfigurable phase-shifted feeding network is a microstrip structure with a single switching feeding point and a narrow bandwidth, the frequency tuning range of the antenna array is only 33%. At the same time, due to the discontinuity of the hexagonal patch and the surrounding rectangular patch structure and the large number of loaded varactor diodes, the gain value of the antenna fluctuates by more than 5dB during frequency tuning. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and propose a frequency, polarization and radiation pattern reconfigurable antenna unit and array, aiming to solve the technical problems of narrow frequency tuning range and large gain fluctuation in the prior art.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes a tuned microstrip antenna unit 1 and a reconfigurable feeding phase-shifting network 2 stacked up and down, wherein the reconfigurable feeding phase-shifting network 2 includes a Wilkinson power division network 21; the tuned microstrip antenna unit 1 includes a circular radiation patch 11 etched with a circular ring gap and four varactor diodes 12 bridged across the circular ring gap; the two sides of the input branch of the Wilkinson power division network 21 are respectively connected to a first C-type branch 22 and a second C-type branch 23 through PIN diodes, and the first output branch is loaded with two open-circuit microstrip lines 24 and two short-circuit microstrip lines 25. The output port of the first output branch is connected to two first feeding point microstrips through a PIN diode, and the output port of the second output branch is connected to two second feeding point microstrips whose impedance values ​​are not equal to those of the first feeding point microstrips through a PIN diode, and the four feeding points form a structure with spatial central symmetry and asymmetric impedance values.

[0006] As an optimization, the tuned microstrip antenna unit 1 also includes a first dielectric substrate 13 and a DC bias pad 14, the circular radiation patch 11 is printed on the upper surface of the first dielectric substrate 13, the annular gap divides the circular radiation patch 11 into a circular patch located in the center and an annular patch nested therewith, and a high-frequency inductor 15 is connected across the annular patch and the DC bias pad 14; a metal floor 16 is printed on the lower surface of the first dielectric substrate 13; the reverse bias voltage of the varactor diode 12 is controlled by the DC bias pad 14 to achieve antenna tuning between 1.4 GHz and 2.3 GHz.

[0007] As an optimization, the center of the circular radiation patch 11 is located on the center normal line of the first dielectric substrate 13 .

[0008] As an optimization, the circular radiation patch 11, wherein the circular gap, and the circular patches divided by the circular gap, and the circular patches nested therein coincide with their centers.

[0009] As an optimization, the reconfigurable feeding phase-shifting network 2 also includes a second dielectric substrate 26 with a Wilkinson power division network 21 printed on the lower surface; the two short-circuit microstrip lines 25 are connected to the metal floor 16 through metallized vias; the impedance values ​​of the two first feeding point microstrips in the Wilkinson power division network 21 are greater than the impedance values ​​of the two second feeding point microstrips, and the four feeding points are connected to the circular patch of the circular radiation patch 11 divided by the circular ring gap through metallized vias.

[0010] As an optimization, in the reconfigurable feeding phase-shifting network 2 , the first C-type branch 22 and the second C-type branch 23 both adopt a coupled microstrip structure, and the length and the gap width of the first C-type branch 22 are smaller than those of the second C-type branch 23 .

[0011] As an optimization, the impedance value of the two feeding point microstrips on the second output end is 50Ω.

[0012] As an optimization, the impedance values ​​of the open-circuit microstrip line 24 and the short-circuit microstrip line 25 are twice the impedance values ​​of the two feeding point microstrips on the first output end.

[0013] As an optimization, the input branch of the Wilkinson power splitter network 21 is divided into three sections, and a PIN diode is loaded between each adjacent section. The first C-type branch 22 is connected between the first and second sections through two PIN diodes, and the second C-type branch 23 is connected between the second and third sections through two PIN diodes.

[0014] A frequency, polarization and directionality pattern reconfigurable antenna array comprises M rows and N columns of the frequency, polarization and directionality pattern reconfigurable antenna units described in claim 1, M≥4, N≥4.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The circular radiation patch in the broadband tuned microstrip antenna unit of the present invention is structurally continuous with the circular radiation patch etched by the circular gap, and only four varactor diodes are loaded on the circular gap, thereby avoiding the influence of the discontinuity of the hexagonal patch and the surrounding rectangular patch structure and the large number of loaded varactor diodes on the gain value fluctuation in the prior art. Experimental results show that the gain value fluctuation within the tuning bandwidth of the present invention is within 2.5dB.

[0017] 2. In the present invention, since two open-circuit microstrip lines and two short-circuit microstrip lines are loaded on the first output branch of the Wilkinson power divider network in the reconfigurable feeding phase-shifting network, and the broadband tuned microstrip antenna unit is fed through four feeding points with spatial central symmetry and asymmetric impedance values, a good matching effect can be maintained between the reconfigurable feeding phase-shifting network and the broadband tuned microstrip antenna unit within a broadband range. Experimental results show that the present invention can achieve an antenna tuning bandwidth of 49%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the antenna unit of the present invention.

[0019] Figure 2 It is a schematic structural diagram of the tuned microstrip antenna unit of the present invention.

[0020] Figure 3 It is a structural schematic diagram of the reconfigurable feeding phase-shifting network of the present invention.

[0021] Figure 4 It is a schematic diagram of the structure of the Wilkinson power splitter network of the present invention;

[0022] Figure 5 is a simulation result diagram of the gain and axial ratio of the reconfigurable antenna unit at different frequencies of the present invention;

[0023] Figure 6 This is a diagram of the beam scanning simulation result of the reconfigurable antenna array of the present invention at 1.5 GHz;

[0024] Figure 7 This is a diagram of the beam scanning simulation result of the reconfigurable antenna array of the present invention at 1.65GHz;

[0025] Figure 8 This is a diagram of the beam scanning simulation result of the reconfigurable antenna array of the present invention at 1.98 GHz;

[0026] Fig. 9 This is a diagram of the beam scanning simulation result of the reconfigurable antenna array of the present invention at 2.2 GHz. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0028] Reference Figure 1 The antenna unit of the present invention includes a tuned microstrip antenna unit 1 and a reconfigurable feeding phase shift network 2 stacked up and down, and the tuned microstrip antenna unit 1 includes a metal floor 16.

[0029] Reference Figure 2 The tuned microstrip antenna unit 1 includes a circular radiation patch 11 with a radius of 35 mm and etched with a circular gap, and four varactor diodes 12 connected across the circular gap; it also includes a first dielectric substrate 13 with a relative dielectric constant of 4.4 and a thickness of 3.5 mm and a DC bias pad 14, wherein the circular radiation patch 11 is printed on the upper surface of the first dielectric substrate 13, and the circular gap divides the circular radiation patch 11 into a circular patch located in the center and a circular patch nested therewith, and the circular gap, as well as the circular patches divided by the circular gap and the circular patches nested therewith, are arranged on the surface of the first dielectric substrate 13. The centers of the annular patches coincide with each other; a high-frequency inductor 15 is connected across the annular patch and the DC bias pad 14; a metal floor 16 is printed on the lower surface of the first dielectric substrate 13; the reverse bias voltage of the varactor 12 is controlled by the DC bias pad 14, and the varactor responds to different capacitance values ​​under different reverse bias voltages, thereby changing the equivalent circuit structure of the antenna radiation patch, enabling the antenna to work at different frequencies, and the capacitance of the varactor varies within the range of 0.63pF to 2.67pF, which can achieve antenna tuning between 1.4GHz and 2.3GHz.

[0030] Reference Figure 3 , the reconfigurable feeding phase shifting network 2 includes a bottom surface printed with Figure 4The second dielectric substrate 26 of the Wilkinson power splitter network 21 shown in the figure has a relative dielectric constant of 4.4 and a thickness of 1 mm; the two sides of the input branch of the Wilkinson power splitter network 21 are connected to a first C-type branch 22 and a second C-type branch 23 through PIN diodes, respectively, and the lengths thereof are 10.4 mm and 14.4 mm, respectively; the first output branch of the Wilkinson power splitter network 21 is loaded with two open-circuit microstrip lines 24 and two short-circuit microstrip lines 25 connected to the metal floor 16 through metallized vias, the output port of the first output branch is connected to two first feeding point microstrips through a PIN diode, and the impedance value thereof is 62 ohms, and the output port of the second output branch is connected to two second feeding point microstrips through a PIN diode, and the impedance value thereof is not equal to that of the first feeding point microstrips. The feeding point microstrip has an impedance value of 50 ohms, and the four feeding points form a structure with spatial central symmetry and asymmetric impedance value, and are connected to the circular patch 11 after being divided by a circular ring gap through a metallized via; the four feeding points form a structure with asymmetric impedance value and two open-circuit short-circuit microstrip lines 24 and a short-circuit microstrip line 25, which can broaden the working bandwidth of the reconfigurable feeding phase-shifting network 2; the spatial central symmetric structure formed by the four feeding points and the first C-type branch 22 and the second C-type branch 23 can realize two different circular polarization states and provide four different radiation phases of 0°, 90°, 180°, and 270°; the feeding point position is at 1 / 5 of the radius of the circular radiation patch, and the feeding point at a specific position can reduce the gain value fluctuation of the antenna unit at different operating frequencies.

[0031] For the reconfigurable feeding phase-shift network 2, the first C-type branch 22 and the second C-type branch 23 both adopt a coupled microstrip structure, and the length and gap width of the first C-type branch 22 are smaller than those of the second C-type branch 23; the two feeding point microstrips on the second output end have an impedance value of 50Ω; the impedance values ​​of the open-circuit microstrip line 24 and the short-circuit microstrip line 25 are twice the impedance values ​​of the two feeding point microstrips on the first output end, which can achieve the broadband working characteristics of the reconfigurable feeding phase-shift network.

[0032] The Wilkinson power splitter network 21 has its input branches divided into three sections, each of which is loaded with a PIN diode. The first C-type branch 22 is connected between the first and second sections through two PIN diodes, and the second C-type branch 23 is connected between the second and third sections through two PIN diodes. A stable 90° phase shift can be achieved in different frequency bands by switching different PIN diodes.

[0033] The fourteen PIN diodes in the reconfigurable feed phase shift network 2 are divided into V 1 ~V 8 Eight groups, among which the PIN diodes on the two feeding points of the first output end are V 2 and V4 , the PIN diodes on the two feeding points of the second output are V 1 and V 3 The input branches of the Wilkinson power divider network 21 are divided into adjacent segments, each of which is loaded with a PIN diode with a voltage V 5 and V 6 The PIN diode connected to the first and second sections of the input branch 22 is V 7 The PIN diode connected to the second and third sections of the input branch of the second C-type branch 22 is V 8 The on and off conditions of these eight groups of PIN diodes are represented by 1 and 0, C s It indicates the capacitance of the varactor diode at different reverse bias voltages, LHCP and RHCP respectively indicate left-hand circular polarization and right-hand circular polarization. The corresponding relationship between the working state of the antenna unit and the working state of the varactor diode and the PIN diode is shown in the following table.

[0034]

[0035]

[0036] The reconfigurable antenna array in the present invention is a periodically arranged planar structure composed of 4×4 antenna units, with an array element spacing of 72mm, a total area of ​​320mm×320mm, and a cross-sectional height of 4.5mm; by changing the on-off state of the PIN diode in the reconfigurable feeding phase shift network 1, the radiation phase of different antenna units can be changed to achieve ±30° two-dimensional scanning of the antenna array.

[0037] The technical effects of the present invention are further illustrated below through simulation experiments.

[0038] 1. Simulation conditions and contents:

[0039] Simulation 1: The tuning characteristics of the reconfigurable antenna unit of the present invention are simulated using the simulation software CST MICROWAVE STUDIO. The results are as follows: Figure 5 As shown;

[0040] Simulation 2, using the simulation software CST MICROWAVE STUDIO to simulate the beam scanning performance of the reconfigurable antenna array of the present invention, the result is shown in the figure Figure 6 , Figure 7 , Figure 8 and Fig. 9 shown.

[0041] 2. Analysis of simulation results:

[0042] Reference Figure 5, the horizontal axis is frequency, the left axis is gain, and the right axis is axial ratio. The solid line and the dotted line are the antenna gain and axial ratio curves at different operating frequencies. Figure 5 It can be seen that between 1.4GHz and 2.3GHz, the gain value at different frequencies changes from 2.5dB to 5dB as the frequency increases, realizing the frequency tuning function between 1.4GHz and 2.3GHz, and the gain fluctuation range is within 2.5dB. In addition, the axial ratio is less than 3dB at different operating frequencies, and has good circular polarization performance.

[0043] Reference Figure 6 (a), the horizontal axis is the scanning angle, the left axis is the gain, and the content is the antenna at the operating frequency of 1.5GHz, the azimuth plane is The gain curves of different scanning angles on the surface, the solid line and the dotted line are the gain curves corresponding to left-hand circular polarization and right-hand circular polarization respectively. The antenna array beam scanning simulation results show that the reconfigurable antenna array in the present invention can be at 1.5GHz, The scanning angle of ±30° is achieved on the plane, the number of pattern reconstruction states is 5, and the cross-polarization ratio between left-hand circular polarization and right-hand circular polarization is greater than 15dB, indicating the good circular polarization performance of the antenna array.

[0044] Reference Figure 6 (b), the horizontal axis is the scanning angle, the left axis is the gain, and the content is the antenna at the operating frequency of 1.5GHz, the azimuth plane is The gain curves of different scanning angles on the surface, the solid line and the dotted line are the gain curves corresponding to left-hand circular polarization and right-hand circular polarization respectively. The antenna array beam scanning simulation results show that the reconfigurable antenna array in the present invention can be at 1.5GHz, The scanning angle of ±30° is achieved on the plane, the number of pattern reconstruction states is 5, and the cross-polarization ratio between left-hand circular polarization and right-hand circular polarization is greater than 15dB, indicating the good circular polarization performance of the antenna array.

[0045] Reference Figure 7 , Figure 8 , Fig. 9 The beam scanning simulation results show that the reconfigurable antenna array in the present invention can be used at 1.65GHz, 1.98GHz, and 2.2GHz. Face to face ±30° scanning is achieved on the surface, the number of pattern reconstruction states is 5, and the cross-polarization ratio between left-hand polarization and right-hand polarization is greater than 15dB, indicating the good circular polarization performance of the antenna array and good frequency, polarization and pattern reconfiguration performance.

[0046] from Figure 6 , Figure 7 , Figure 8 , Fig. 9Overall, the reconfigurable antenna array can achieve two-dimensional ±30° beam scanning at different frequencies, and has good circular polarization performance, indicating the tuning function of the reconfigurable antenna array with a bandwidth of 49%.

[0047] The above description is only a preferred embodiment of the present invention and does not constitute a limitation to the present invention. A person skilled in the art may make several modifications and improvements without departing from the innovative concept of the present invention, but these changes shall all fall within the scope of protection of the present invention.

Claims

1. A frequency, polarization and directional pattern reconfigurable antenna unit, comprising a tuned microstrip antenna unit (1) stacked up and down and a reconfigurable feeding phase shift network (2) including a Wilkinson power division network (21); characterized in that: The tuned microstrip antenna unit (1) comprises a circular radiation patch (11) etched with a circular annular gap and four variable capacitance diodes (12) bridged across the circular annular gap; the two sides of the input branch of the Wilkinson power splitter network (21) are respectively connected to a first C-type branch (22) and a second C-type branch (23) through PIN diodes; two open-circuit microstrip lines (24) and two short-circuit microstrip lines (25) are loaded on the first output branch; the output port of the first output branch is connected to two first feeding point microstrips through a PIN diode; the output port of the second output branch is connected to two second feeding point microstrips with impedance values ​​unequal to those of the first feeding point microstrips through a PIN diode; the four feeding points form a structure with spatial center symmetry and asymmetric impedance values.

2. The antenna unit according to claim 1, characterized in that The tuned microstrip antenna unit (1) further comprises a first dielectric substrate (13) and a DC bias pad (14); the circular radiation patch (11) is printed on the upper surface of the first dielectric substrate (13); the circular annular gap divides the circular radiation patch (11) into a circular patch located at the center and a circular annular patch nested therewith; a high-frequency inductor (15) is bridged between the circular annular patch and the DC bias pad (14); a metal floor (16) is printed on the lower surface of the first dielectric substrate (13); and antenna tuning between 1.4 GHz and 2.3 GHz is achieved by controlling the reverse bias voltage of the varactor diode (12) through the DC bias pad (14).

3. The antenna unit according to claim 2, characterized in that The circular radiation patch (11) has its center located on the center normal line of the first dielectric substrate (13).

4. The antenna unit according to claim 2, characterized in that The circular radiation patch (11) has a circular gap, and the centers of the circular patches divided by the circular gap and the circular patches nested therein coincide with each other.

5. The antenna unit according to claim 2, characterized in that: The reconfigurable feeding phase-shifting network (2) also includes a second dielectric substrate (26) with a Wilkinson power division network (21) printed on the lower surface; the two short-circuit microstrip lines (25) are connected to the metal floor (16) through metallized vias; the impedance values ​​of the two first feeding point microstrips in the Wilkinson power division network (21) are greater than the impedance values ​​of the two second feeding point microstrips, and the four feeding points are connected to the circular patch of the circular radiation patch (11) divided by the circular ring gap through the metallized vias; The four feeding points form an asymmetric impedance structure and two open-circuit short-circuit microstrip lines (24) and a short-circuit microstrip line (25), which can broaden the working bandwidth of the reconfigurable feeding phase-shifting network (2); the spatially centrally symmetrical structure formed by the four feeding points and the first C-type branch (22) and the second C-type branch (23) can realize two different circular polarization states and provide four different radiation phases of 0°, 90°, 180°, and 270°; the feeding point is located at 1 / 5 of the radius of the circular radiation patch, and the feeding point at a specific position can reduce the gain value fluctuation of the antenna unit at different working frequencies.

6. The antenna unit according to claim 5, characterized in that In the reconfigurable feeding phase-shifting network (2), the first C-type branch (22) and the second C-type branch (23) both adopt a coupled microstrip structure, and the length and gap width of the first C-type branch (22) are smaller than those of the second C-type branch (23).

7. The antenna unit according to claim 5, characterized in that: The two feeding point microstrips on the second output end have an impedance value of 50Ω.

8. The antenna unit according to claim 5, characterized in that The impedance values ​​of the open-circuit microstrip line (24) and the short-circuit microstrip line (25) are twice the impedance values ​​of the two feeding point microstrips on the first output end.

9. The antenna unit according to claim 5, characterized in that: The Wilkinson power splitter network (21) has an input branch divided into three sections, each of which is loaded with a PIN diode. The first C-type branch (22) is connected between the first and second sections via two PIN diodes, and the second C-type branch (23) is connected between the second and third sections via two PIN diodes.

10. A frequency, polarization and pattern reconfigurable antenna array, characterized in that: It comprises M rows and N columns of the frequency, polarization and direction pattern reconfigurable antenna units as described in claim 1, M≥4, N≥4.

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