A frequency, polarization, and pattern reconfigurable antenna element and array

Abstract

This invention proposes a frequency, polarization, and pattern reconfigurable antenna element and array. The antenna element includes stacked tuned microstrip antenna elements and a reconfigurable feed phase-shifting network. The tuned microstrip antenna element includes a circular radiating patch with an etched annular slot and four varactor diodes connected across the annular slot. The two output ports of the Wilkinson power divider network in the reconfigurable feed phase-shifting network are each connected to two feed point microstrips via PIN diodes. The four feed points form a spatially symmetrical but impedance-asymmetrical structure. The circular radiating patch and the annular radiating patch in the antenna element of this invention have structural continuity, and only four varactor diodes are loaded on the annular slot, reducing gain fluctuations. Furthermore, feeding the antenna element through four spatially symmetrical but impedance-asymmetrical feed points ensures good matching between the feed phase-shifting network and the antenna element over a wide bandwidth, thus broadening the antenna tuning bandwidth.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology and relates to a reconfigurable antenna element and array, specifically a frequency, polarization, and pattern reconfigurable antenna and array, which can be used in wireless communication and other fields. Background Technology

[0002] With the rapid development of wireless communication technology and the diversification of application scenarios, higher demands are being placed on antenna performance. Traditional antenna designs often have a single operating frequency, radiation direction, or polarization mode, making it difficult to meet the current application requirements of communication technologies for multiple functions and scenarios. Reconfigurable antennas, because they can dynamically adjust their operating frequency, polarization mode, or radiation direction, have become one of the hot topics in current antenna technology research. Frequency, Polarization, and Direction Figure 3 Dimensionally collaborative reconfigurable antenna arrays enable communication systems to switch between multiple functions in real time to the greatest extent possible.

[0003] Current research on antenna arrays with coordinated reconfiguration of three parameters often suffers from narrow frequency tuning bandwidth, poor pattern stability, and large fluctuations in antenna gain, limiting their practical applications. For example, in 2021, Jun Hu disclosed a hybrid reconfigurable antenna array for frequency, polarization, and pattern in his paper "A Reconfigurable 1 × 4 Circularly Polarized Patch Array Antenna With Frequency, Radiation Pattern, and Polarization Agility." This array features a hexagonal patch at its center, with six rectangular patches on each side. Six varactor diodes bridge the hexagonal and rectangular patches. By adjusting the capacitance of the varactor diodes between the hexagonal and rectangular patches, frequency adjustment and polarization reconfiguration can be achieved. A reconfigurable phase-shifting feed network enables pattern scanning. This design can achieve five pattern reconfiguration states within a frequency adjustable range, covering ±50°. However, because its reconfigurable phase-shifting feed network is a single switching feed point and a narrow bandwidth microstrip structure, 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 this invention is to address the shortcomings of the prior art by proposing a frequency, polarization, and pattern reconfigurable antenna element 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 objectives, the technical solution adopted by the present invention includes a tuned microstrip antenna unit 1 stacked in upper and lower layers and a reconfigurable feed phase-shifting network 2. The reconfigurable feed phase-shifting network 2 includes a Wilkinson power divider network 21. The tuned microstrip antenna unit 1 includes a circular radiating patch 11 etched with an annular slot and four varactor diodes 12 connected across the annular slot. The two sides of the input stub of the Wilkinson power divider network 21 are respectively connected to a first C-type stub 22 and a second C-type stub 23 via PIN diodes. Two open-circuit microstrip lines 24 and two short-circuit microstrip lines 25 are loaded on the first output stub. The output port of the first output stub is connected to two first feed point microstrips via PIN diodes. The output port of the second output stub is connected to two second feed point microstrips with impedance values ​​unequal to those of the first feed point microstrips via PIN diodes. The four feed points form a spatially symmetrical but impedance-asymmetrical structure.

[0006] As an optimization, the tuned microstrip antenna unit 1 further includes a first dielectric substrate 13 and a DC bias pad 14. The circular radiating patch 11 is printed on the upper surface of the first dielectric substrate 13. The annular gap divides the circular radiating patch 11 into a central circular patch and a nested annular patch. A high-frequency inductor 15 is connected between the annular patch and the DC bias pad 14. A metal ground plane 16 is printed on the lower surface of the first dielectric substrate 13. 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.

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

[0008] As an optimization, the circular radiating patch 11 has an annular gap, and the centers of the circular patches divided by the annular gap and the nested annular patches coincide.

[0009] As an optimization, the reconfigurable feed phase-shifting network 2 further includes a second dielectric substrate 26 on which a Wilkinson power divider network 21 is printed on its lower surface; the two short-circuited microstrip lines 25 are connected to the metal ground plane 16 through metallized vias; the impedance values ​​of the two first feed point microstrips in the Wilkinson power divider network 21 are greater than the impedance values ​​of the two second feed point microstrips, and the four feed points are connected to the circular patch 11 divided by the annular gap through metallized vias.

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

[0011] As an optimization, the two feed point microstrips on the output port of the second output stub have an impedance value of .

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

[0013] As an optimization, the Wilkinson power divider network 21 has its input stub divided into three segments, with a PIN diode loaded between each adjacent segment. The first C-type stub 22 is connected between the first and second segments by two PIN diodes, and the second C-type stub 23 is connected between the second and third segments by two PIN diodes.

[0014] A frequency, polarization, and pattern reconfigurable antenna array, including OK List the frequency, polarization, and pattern reconfigurable antenna elements mentioned above. , .

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

[0016] 1. The circular radiating patch and the circular radiating patch etched by the annular slot in the broadband tuned microstrip antenna unit of the present invention have structural continuity, and only four varactor diodes are loaded on the annular slot. This avoids the influence of the discontinuity of the hexagonal patch and the surrounding rectangular patch structure and the large number of varactor diodes on the gain value fluctuation of 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 this invention, the first output branch of the Wilkinson power divider in the reconfigurable feed phase-shifting network is loaded with two open-circuit microstrip lines and two short-circuit microstrip lines. The broadband tuned microstrip antenna element is fed through four spatially symmetrical but impedance-asymmetrical feed points. This allows the reconfigurable feed phase-shifting network and the broadband tuned microstrip antenna element to maintain a good matching effect within the broadband range. Experimental results show that this invention can achieve an antenna tuning bandwidth of 49%. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the antenna element of the present invention.

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

[0020] Figure 3 This is a schematic diagram of the reconfigurable feed phase-shifting network of the present invention.

[0021] Figure 4 This is a schematic diagram of the Wilkinson power divider network of the present invention;

[0022] Figure 5 The simulation results show the gain and axial ratio of the reconfigurable antenna element of this invention at different frequencies.

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

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

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

[0026] Figure 9 This is a simulation result of beam scanning at 2.2GHz for the reconfigurable antenna array of this invention. Detailed Implementation

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

[0028] Reference Figure 1 The antenna unit of the present invention includes a tuned microstrip antenna unit 1 stacked in upper and lower layers and a reconfigurable feed phase shifting network 2, wherein the tuned microstrip antenna unit 1 includes a metal ground plane 16.

[0029] Reference Figure 2 The tuned microstrip antenna unit 1 includes a circular radiating patch 11 with a radius of 35 mm etched with an annular slot and four varactor diodes 12 connected across the annular slot; it also includes a first dielectric substrate 13 with a relative permittivity of 4.4 and a thickness of 3.5 mm and a DC bias pad 14. The circular radiating patch 11 is printed on the upper surface of the first dielectric substrate 13. The annular slot divides the circular radiating patch 11 into a central circular patch and nested annular patches. The annular slot, the circular patch divided by the annular slot, and the nested annular patches... The centers of the annular patch coincide; a high-frequency inductor 15 is connected between the annular patch and the DC bias pad 14; a metal ground plane 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, and the varactor diode responds with different capacitance values ​​under different reverse bias voltages, thereby changing the equivalent circuit structure of the antenna radiating patch, enabling the antenna to operate at different frequencies. The capacitance value of the varactor diode varies from 0.63pF to 2.67pF, enabling antenna tuning between 1.4GHz and 2.3GHz.

[0030] Reference Figure 3 The reconfigurable feed phase-shifting network 2 includes a lower surface printed with, for example, Figure 4 The second dielectric substrate 26 of the Wilkinson power divider network 21 shown has a relative permittivity of 4.4 and a thickness of 1 mm. The input stub of the Wilkinson power divider network 21 is connected to a first C-type stub 22 and a second C-type stub 23 via PIN diodes on both sides, with lengths of 10.4 mm and 14.4 mm respectively. The first output stub of the Wilkinson power divider network 21 has two open-circuit microstrip lines 24 and two short-circuit microstrip lines 25 connected to a metal ground plane 16 via metallized vias. The output port of the first output stub is connected to two first feed point microstrips with an impedance of 62 ohms via PIN diodes. The output port of the second output stub is connected to two second feed point microstrips with impedances unequal to the first feed point microstrips via PIN diodes. The feed point microstrip has an impedance of 50 ohms. The four feed points form a spatially symmetrical structure with an impedance asymmetry, and are connected to the circular radiating patch 11, which is divided by an annular slot, through metallized vias. The asymmetric impedance structure formed by the four feed points and the two open-circuit and short-circuit microstrip lines 24 and 25 can widen the operating bandwidth of the reconfigurable feed phase-shifting network 2. The spatially symmetrical structure formed by the four feed points and the first C-shaped stub 22 and the second C-shaped stub 23 can realize two different circular polarization states and provide four different radiation phases: 0°, 90°, 180°, and 270°. The feed point is located at 1 / 5 of the radius of the circular radiating patch. The feed point at a specific location can reduce the gain fluctuation of the antenna element at different operating frequencies.

[0031] For the reconfigurable feed phase-shifting network 2, both the first C-type stub 22 and the second C-type stub 23 adopt a coupled microstrip structure, and the length and slot width of the first C-type stub 22 are smaller than those of the second C-type stub 23; the impedance value of the two feed point microstrips on the output port of the second output stub is... The open-circuit microstrip line 24 and the short-circuit microstrip line 25 have an impedance value that is twice the impedance value of the two feed points on the first output terminal, which enables the broadband operation characteristics of the reconfigurable feed phase-shifting network.

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

[0033] The fourteen PIN diodes in the reconfigurable feed phase-shifting network 2 are divided into Eight groups, of which the two feed points on the first output terminal are PIN diodes on the microstrip. and The two feed points on the second output terminal are PIN diodes on the microstrip. and The Wilkinson power divider network 21 has a PIN diode loaded between each adjacent segment of its input stub. and The first C-type stub 22 is connected to the first and second segments of the input stub via PIN diodes. The second C-type stub 22 is connected to the second and third segments of the input stub via PIN diodes. The on / off state of these eight sets of PIN diodes is represented by 1 and 0. The values ​​represent the capacitance of the varactor diode under different reverse bias voltages. LHCP and RHCP represent left-hand circular polarization and right-hand circular polarization, respectively. The correspondence between the operating states of the antenna element and the operating states of the varactor diode and PIN diode is shown in the table below.

[0034]

[0035] The reconfigurable antenna array in this invention is a planar structure composed of 4×4 antenna elements arranged periodically, with an element spacing of 72mm, a total area of ​​320mm×320mm, and a total cross-sectional height of 4.5mm. By changing the on / off state of the PIN diodes in the reconfigurable feed phase shifting network 1, the radiation phase of different antenna elements can be changed, realizing ±30° two-dimensional scanning of the antenna array.

[0036] The technical effects of the present invention will be further illustrated by the following simulation experiments.

[0037] 1. Simulation conditions and content:

[0038] Simulation 1: The tuning characteristics of the reconfigurable antenna element of this invention were simulated using the simulation software CST MICROWAVE STUDIO. The results are as follows: Figure 5 As shown;

[0039] Simulation 2: The beam scanning performance of the reconfigurable antenna array of the present invention was simulated using the simulation software CST MICROWAVE STUDIO. The results are shown in the figure below. Figure 6 , Figure 7 , Figure 8 and Figure 9 As shown.

[0040] 2. Simulation Result Analysis:

[0041] Reference Figure 5The horizontal axis represents frequency, the left axis represents gain, and the right axis represents axial ratio. The solid and dashed lines are the antenna gain and axial ratio curves at different operating frequencies, respectively. 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. Moreover, the axial ratio is less than 3dB at different operating frequencies, which shows good circular polarization performance.

[0042] Reference Figure 6 (a) The horizontal axis represents the scanning angle, and the left axis represents the gain. The content shows the antenna's azimuth plane at an operating frequency of 1.5 GHz. Gain curves at different scanning angles are shown on the surface. The solid and dashed lines represent the gain curves for left-hand and right-hand circular polarization, respectively. Simulation results of antenna array beam scanning show that the reconfigurable antenna array in this invention can achieve gain at 1.5 GHz. The antenna array achieves scanning at an angle of ±30° on the surface, with 5 reconstructed radiation states. The cross-polarization ratio between left-hand circular polarization and right-hand circular polarization is greater than 15dB, indicating good circular polarization performance.

[0043] Reference Figure 6 (b) The horizontal axis represents the scanning angle, and the left axis represents the gain. The content shows the antenna's azimuth plane at an operating frequency of 1.5 GHz. Gain curves at different scanning angles are shown on the surface. The solid and dashed lines represent the gain curves for left-hand and right-hand circular polarization, respectively. Simulation results of antenna array beam scanning show that the reconfigurable antenna array in this invention can achieve gain at 1.5 GHz. The antenna array achieves scanning at an angle of ±30° on the surface, with 5 reconstructed radiation states. The cross-polarization ratio between left-hand circular polarization and right-hand circular polarization is greater than 15dB, indicating good circular polarization performance.

[0044] Reference Figure 7 , Figure 8 , Figure 9 Beam scanning simulation results show that the reconfigurable antenna array in this invention can operate at 1.65 GHz, 1.98 GHz, and 2.2 GHz. Face to face The antenna array achieves ±30° scanning on the surface, has 5 reconfigurable states for the radiation pattern, and has a cross-polarization ratio of more than 15dB between left-hand and right-hand circular polarization, indicating good circular polarization performance and good frequency, polarization, and radiation pattern reconfigurability.

[0045] from Figure 6 , Figure 7 , Figure 8 , Figure 9In summary, the reconfigurable antenna array can achieve two-dimensional ±30° beam scanning at different frequencies, and all of them have good circular polarization performance, demonstrating the tuning capability of the reconfigurable antenna array with 49% bandwidth.

[0046] The above description is only a preferred embodiment of the present invention and does not constitute a limitation on the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the innovative concept of the present invention, but these changes all fall within the protection scope of the present invention.

Claims

1. A frequency, polarization, and pattern reconfigurable antenna element, comprising stacked tuned microstrip antenna elements (1) and a reconfigurable feed phase-shifting network (2) including a Wilkinson power divider network (21); characterized in that, The tuned microstrip antenna unit (1) includes a circular radiating patch (11) etched with an annular slot and four varactor diodes (12) connected across the annular slot. The Wilkinson power divider network (21) has a first C-type stub (22) and a second C-type stub (23) connected to both sides of the input stub via PIN diodes. The first output stub is loaded with two open-circuit microstrip lines (24) and two short-circuit microstrip lines (25). The output port of the first output stub is connected to two first feed point microstrips via PIN diodes. The output port of the second output stub is connected to two second feed point microstrips with impedance values ​​that are not equal to those of the first feed point microstrips via PIN diodes. The four feed points form a spatially symmetrical structure with asymmetrical impedance values.

2. The antenna element according to claim 1, characterized in that, The tuned microstrip antenna unit (1) further includes a first dielectric substrate (13) and a DC bias pad (14). The circular radiating patch (11) is printed on the upper surface of the first dielectric substrate (13). The annular gap divides the circular radiating patch (11) into a circular patch located in the center and an annular patch nested therewith. A high-frequency inductor (15) is connected between the annular patch and the DC bias pad (14). A metal ground plane (16) is printed on the lower surface of the first dielectric substrate (13). 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 element according to claim 2, characterized in that, The circular radiating patch (11) has its center located on the center normal of the first dielectric substrate (13).

4. The antenna element according to claim 2, characterized in that, The circular radiating patch (11) includes an annular slit, and the circular patches divided by the annular slit and the annular patches nested therein have their centers coincident.

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

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

7. The antenna element according to claim 5, characterized in that, The two feed point microstrips at the output port of the second output stub have an impedance value of .

8. The antenna element 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 feed points on the first output terminal.

9. The antenna element according to claim 5, characterized in that, The Wilkinson power divider network (21) has its input stub divided into three segments, with a PIN diode loaded between each adjacent segment. The first C-type stub (22) is connected between the first and second segments by two PIN diodes, and the second C-type stub (23) is connected between the second and third segments by two PIN diodes.

10. A frequency, polarization, and pattern reconfigurable antenna array, characterized in that, include OK List the frequency, polarization, and pattern reconfigurable antenna element as described in claim 1. , .

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