Two-dimensional beam scanning antenna based on frequency adjustment and electric adjustment

Abstract

The invention discloses a two-dimensional beam scanning antenna based on frequency adjustment and electric adjustment, and belongs to the technical field of communication and radar detection, and the antenna comprises at least two periodic units which are arranged on a substrate and are in cascade arrangement along a wave propagation direction; each periodic unit comprises a leaky-wave antenna module arranged along the wave propagation direction, and realizes one-dimensional beam scanning in the wave propagation direction based on frequency adjustment by using the dispersion effect of a leaky-wave antenna; each periodic unit further comprises an electrically tunable directional diagram reconfigurable module which is arranged in the direction orthogonal to the wave propagation direction, and the electrically tunable directional diagram reconfigurable modules achieve another-dimensional beam scanning in the orthogonal direction based on electrical signal adjustment. According to the novel design, the size and the weight of the antenna are reduced by times, a single-layer PCB structure is adopted, the antenna is suitable for being arranged in a lightweight and miniaturized equipment platform, only two sets of bias voltages are used, the frequency scanning characteristic of the leaky-wave antenna is combined, wave beam scanning is achieved in a two-dimensional space, and the radiation state switching is flexible and rapid.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of communication and radar detection, and particularly relates to a two-dimensional beam scanning antenna based on frequency adjustment and electric adjustment. BACKGROUND

[0002] In a communication and radar detection system, a beam scanning antenna plays an important role. The beam scanning antenna can realize a dynamically variable beam radiation state to cope with real-time changes in a communication or detection area. Currently, a phased array body is usually used to realize beam scanning of the antenna. However, the phased array antenna is not suitable for all use scenarios due to problems such as high cost, complex system, large volume and weight. A leaky-wave antenna realizes beam scanning by adjusting a frequency to change an equivalent phase difference between units, which avoids the use of phase shifters, power dividers and other devices. The leaky-wave antenna adopts a cascaded feeding mode, has a simple structure and meets the urgent needs of modern communication and radar systems for low-cost and lightweight beam scanning antennas, and is suitable for mass assembly.

[0003] To realize beam scanning in a two-dimensional space, the antenna structure usually needs to be expanded from a one-dimensional linear array to a two-dimensional surface array, such as a two-dimensional frequency scanning leaky-wave antenna array and a two-dimensional frequency scanning method disclosed in a patent document with the publication number CN116345188A. However, the surface array leaky-wave antenna occupies an area that increases exponentially, and needs a complex feeding network. Therefore, it has important research significance to realize beam scanning in a two-dimensional space under the premise of compact and simple structure.

[0004] A patent document with the publication number CN111682314A discloses a double linear polarization electrically controlled beam scanning leaky-wave antenna. The antenna sets a varactor diode on a first periodic antenna radiation structure plate and a second periodic antenna radiation structure plate, and uses a microcontroller to control the capacitance value of the varactor diode, thereby controlling the beam scanning range. However, the antenna can only realize beam scanning in one direction along the Y-axis. SUMMARY

[0005] In view of the above, the purpose of the present application is to provide a two-dimensional beam scanning antenna based on frequency adjustment and electric adjustment, which overturns the surface array architecture of the traditional two-dimensional beam scanning leaky-wave antenna and instead uses a linear array architecture. The dispersion effect of the leaky-wave antenna is utilized in the wave propagation direction, and beam scanning is realized based on frequency adjustment. The electrically adjustable directional pattern reconfigurable module is arranged in a direction orthogonal to the wave propagation direction, and beam scanning is realized in the orthogonal direction based on electric signal adjustment. In this way, beam scanning can be realized in two orthogonal directions, thereby widening the beam scanning range.

[0006] To achieve the above-mentioned purpose, the embodiment provides a two-dimensional beam scanning antenna based on frequency adjustment and electric adjustment, which comprises: The at least two periodic units are arranged on a substrate and are arranged in cascade along a wave propagation direction; Each periodic unit comprises a leaky-wave antenna module arranged along the wave propagation direction, which utilizes the dispersion effect of the leaky-wave antenna to achieve one-dimensional beam scanning in the wave propagation direction based on frequency adjustment; Each periodic unit further comprises an electrically steerable pattern reconfigurable module arranged in a direction orthogonal to the wave propagation direction, which achieves another-dimensional beam scanning in the orthogonal direction based on electric signal adjustment.

[0007] Preferably, the leaky-wave antenna module comprises a section of meandered parallel double line, a pair of wide microstrip lines connected to the meandered parallel double line, and a pair of microstrip stubs connected to the meandered parallel double line and extending in opposite directions.

[0008] Preferably, the meandered parallel double line is printed on the upper and lower surfaces of the substrate as upper and lower branches, respectively, and the current amplitudes of the upper and lower branches are the same and the phases are opposite, only signal transmission is performed, and no radiation is generated.

[0009] Preferably, the pair of wide microstrip lines are printed on the upper surface of the substrate and are symmetric about the central axis of the unit, provide current polarization components in the wave propagation direction, and introduce periodic perturbations, thereby forming a periodic leaky-wave antenna to achieve one-dimensional beam scanning with frequency variation.

[0010] The arrangement of the wide microstrip lines causes a change in the phase difference between the upper and lower branches of the meandered parallel double line. In order to compensate for the phase difference change caused by the wide microstrip lines, a pair of microstrip stubs extending in opposite directions is arranged in each periodic unit. The microstrip stubs are arranged on the lower surface of the substrate, and the opposite extension directions of the microstrip stubs cause the current distributions of the microstrip stubs to cancel each other out, without affecting the radiation response of the antenna, so that the upper and lower branches of the meandered parallel double line restore the reverse phase relationship.

[0011] Preferably, the electrically steerable pattern reconfigurable module comprises two pairs of half-ring microstrip lines, each pair of half-ring microstrip lines comprising two half-ring microstrip lines, and the upper and lower branches of the half-ring microstrip lines are arranged on the upper and lower surfaces of the substrate, respectively, and the two pairs of half-ring microstrip lines are mirror symmetric about the wave propagation direction. The end of each pair of half-ring microstrip lines is provided with a metal through hole, so that each pair of upper and lower half-ring microstrip lines are connected. Each pair of half-ring microstrip lines is connected to the meandered parallel double line through a pair of connecting microstrip lines.

[0012] Preferably, a PIN diode is arranged in each pair of connecting microstrip lines, and the on-off state of each PIN diode is controlled by a different control voltage, thereby controlling the excitation state of the half-ring microstrip line and forming different radiation responses to achieve beam scanning in the orthogonal direction.

[0013] Preferably, the periodic unit at the head and tail is also provided with a transition joint, wherein the transition joint at the head (such as the left transition joint) feeds the entire antenna, and the transition joint at the tail (such as the right transition joint) is connected to a standard load to absorb the remaining energy and prevent the remaining energy from returning to the feeding end to destroy the radiation performance. The inner core of the transition joint at the head and tail is connected to the metal layer on the upper layer of the substrate, and the outer core is connected to the metal layer on the lower layer of the substrate.

[0014] The two-dimensional beam scanning antenna based on frequency adjustment and electric adjustment of the application selects four typical frequency points in the working frequency band (2.4 GHz to 3.4 GHz), and the radiation beam gradually scans from the y<0 area to the y>0 area as the frequency increases; by adjusting the combination of the two groups of control voltages, the on-off state of the two groups of PIN diodes is controlled, and the switching of the radiation beam in the x<0 area and the x>0 area is realized. By combining the frequency adjustment and the control voltage adjustment, the φ - beam scanning in a two-dimensional planar space.

[0015] Compared with the prior art, the application has at least the following beneficial effects: The two-dimensional beam scanning antenna provided by the application adopts a one-dimensional linear array structure, realizes beam scanning in a two-dimensional space, and compared with the traditional two-dimensional beam scanning antenna adopting a two-dimensional surface array structure, the new design brings a foldable reduction in the size and weight of the antenna, and the single-layer PCB structure is suitable for being arranged in a lightweight and small-sized device platform. The two-dimensional beam scanning antenna provided by the application only uses two groups of bias voltages, combines the frequency scanning characteristics of the leaky wave antenna, and realizes beam scanning in a two-dimensional space, and the radiation state switching is flexible and fast. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a structure schematic diagram of the two-dimensional beam scanning antenna provided by the embodiment, wherein (a) and (b) are top views of the upper layer structure and the lower layer structure, respectively; Figure 2 is an S parameter curve of the two-dimensional beam scanning antenna provided by the embodiment; Figure 3 is the radiation response of the two-dimensional beam scanning antenna provided by the embodiment in the xoz plane at two high and low critical frequency points under two electric adjustment modes; is the radiation response of the two-dimensional beam scanning antenna provided by the embodiment in the xoz plane at two high and low critical frequency points under two electric adjustment modes;Figure 4 is the normalized radiation pattern of the two-dimensional beam scanning antenna provided by the embodiment in the plane of θ=90° at four typical frequency points under two electrically adjustable modes; Figure 5 is a curve of the peak gain of the two-dimensional beam scanning antenna provided by the embodiment varying with frequency under two electrically adjustable modes; Note: 1-substrate, 2-SMA joint 1, 3-SMA joint 2, 4-PIN diode S1, 5-PIN diode S2, 6-control voltage V1, 7-control voltage V2, 8-winding parallel double lines, 9-metal through hole, 10-wide microstrip line, 11-semi-ring microstrip line, 12-connection microstrip line, 13-microstrip stub. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the protection scope of the present application.

[0019] As shown in Figure 1 , the two-dimensional beam scanning antenna based on frequency adjustment and electrical adjustment provided by the embodiment includes at least two periodic units arranged on the substrate 1 and cascaded along the wave propagation direction, wherein the wave propagation direction can be the y-axis, and the direction orthogonal to the y-axis is the x-axis, at this time the two-dimensional beam scanning antenna can be composed of five periodic units cascaded along the y-axis.

[0020] In the embodiment, each periodic unit includes a leaky-wave antenna module arranged along the wave propagation direction, which utilizes the dispersion effect of the leaky-wave antenna to realize one-dimensional beam scanning in the wave propagation direction based on frequency adjustment. It also includes an electrically adjustable directional pattern reconfigurable module arranged in the direction orthogonal to the wave propagation direction, which realizes another-dimensional beam scanning in the orthogonal direction based on electrical signal adjustment.

[0021] In the embodiment, the leaky-wave antenna module includes a winding parallel double line 8, a pair of wide microstrip lines 10 connected to both ends of the winding parallel double line 8, and a microstrip stub 13 connected to the winding parallel double line 8 and extending in the opposite direction.

[0022] Among them, the winding parallel double line 8 serves as a transmission structure, which is divided into two branches and printed on the upper and lower surfaces of the substrate 1 respectively. The present application bends the straight parallel double line to change it into a winding shape, thereby reducing the spacing between adjacent units to suppress the grating lobe effect and expand the beam scanning range.

[0023] The parts of the meandered parallel double line 8 printed on the upper surface of the substrate 1 and the parts printed on the lower surface of the substrate 1 are marked as the upper branch and the lower branch respectively, and the current amplitudes of the upper branch and the lower branch are the same and the phases are opposite. Therefore, the currents distributed on the meandered parallel double line 8 cancel each other out, and the meandered parallel double line 8 itself only plays a role in signal transmission and does not generate radiation.

[0024] The wide microstrip line 10 is printed on the upper surface of the substrate 1, and a pair of wide microstrip lines 10 is arranged in each periodic unit. The two wide microstrip lines are symmetrical about the center axis of the unit, which introduces a periodic current element loading along the y-axis direction for the two-dimensional beam scanning antenna, thereby forming a periodic leaky-wave antenna, so that the two-dimensional beam scanning antenna has the function of one-dimensional beam scanning with frequency variation (y-z plane).

[0025] Due to the loading of the wide microstrip line 10 in the upper branch of the meandered parallel double line 8, the opposite phase relationship between the upper branch and the lower branch of the meandered parallel double line 8 is destroyed. Therefore, a pair of microstrip stubs 13 extending in opposite directions is arranged in each periodic unit, and the microstrip stubs 13 are arranged on the lower surface of the substrate 1. In this way, the change in the phase difference between the upper branch and the lower branch of the meandered parallel double line 8 caused by the loading of the wide microstrip line 10 is compensated, so that the opposite phase relationship between the upper branch and the lower branch of the meandered parallel double line 8 is restored. The microstrip stubs 13 extend in opposite directions, so their current distributions cancel each other out and do not affect the radiation response.

[0026] In the embodiment, the electrically adjustable pattern reconfigurable module includes two pairs of half-ring microstrip lines 11. Each pair of half-ring microstrip lines 11 includes two branches of half-ring microstrip lines, and the upper and lower branches of the half-ring microstrip lines are arranged on the upper and lower surfaces of the substrate 1 respectively. The two pairs of half-ring microstrip lines 11 are located at the center axis of each periodic unit and are mirror symmetrical about the y-axis.

[0027] The end of each pair of half-ring microstrip lines 11 is provided with a metal through hole 9, so that each pair of upper and lower half-ring microstrip lines 11 is connected.

[0028] The currents with the same amplitude and opposite directions are distributed on the upper branch and the lower branch of the meandered parallel double line 8. Each pair of half-ring microstrip lines 11 is connected to the meandered parallel double line 8 through a pair of connecting microstrip lines 12. Therefore, the meandered parallel double line 8 can provide a differential feed signal for the upper branch and the lower branch of the connected half-ring microstrip lines 11, and the excited half-ring microstrip lines 11 form φ a current loop in the plane, which is equivalent to a magnetic current element along the z-axis.

[0029] A PIN diode is arranged in each connecting microstrip line 12, and two groups of PIN diodes arranged in the x<0 and x>0 regions are denoted as PIN diode S1 4 and PIN diode S2 5, respectively. For a two-dimensional beam scanning antenna including 5 periodic units, each group includes 10 PIN diodes, and the on-off states of the two groups of PIN diodes are controlled by two different bias voltages V1 and V2, respectively, to control the current distribution on the connecting microstrip line.

[0030] By controlling the current distribution on the connecting microstrip line 12 in the x<0 and x>0 regions, the excitation state of the semi-annular microstrip line 11 in the x<0 and x>0 regions can be controlled, thereby forming different equivalent magnetic current elements.

[0031] In the electrically adjustable mode 1, the bias voltage V1 is 0 V, and the bias voltage V2 is a forward bias voltage, about 3 V; then the PIN diode S1 4 is in an open state, and the PIN diode S2 5 is in a closed state. In the electrically adjustable mode 2, the bias voltage V1 is a forward bias voltage, about 3 V, and the bias voltage V2 is 0 V; then the PIN diode S1 4 is in a closed state, and the PIN diode S2 5 is in an open state.

[0032] The equivalent magnetic current elements formed in the two electrically adjustable modes are in an inverse relationship. The equivalent magnetic current element formed by the semi-annular microstrip line 11 in an excited state and the current element formed by the wide microstrip line 10 along the y axis form a complementary radiation element pair. When the phase of the equivalent magnetic current element is flipped (the phase changes by 180 ° ), the corresponding radiation response also points to the opposite direction. Therefore, by controlling the on-off states of the two groups of PIN diodes, the excitation state of the semi-annular microstrip line can be controlled, different periodic complementary radiation element pairs are excited, different radiation responses are formed, and beam scanning switching in the x-z plane is realized.

[0033] In summary, by combining frequency adjustment and electrical adjustment, the embodiment of the present application can realize beam scanning in a two-dimensional space.

[0034] Next, 2.4-3.4 GHz is selected as the operating frequency band, and the performance parameters of the embodiment of the present application in the operating frequency band are shown.

[0035] Figure 2 The S-parameter curve of the two-dimensional beam scanning antenna of the present application is shown, including S 11 | and S 21 | curve, Figure 2 where the ordinate is S 11 | (dB) or S 21| (dB), and the horizontal axis is frequency (GHz). Due to the fact that the antenna structure is not completely symmetrical, the S parameter curves of the electrically adjustable mode 1 and the electrically adjustable mode 2 are not completely coincident, but in the two electrically adjustable modes, the S parameter curves can meet the requirement of impedance matching in the working frequency band S 11 | less than -9 dB, which shows good impedance matching performance in the two electrically adjustable modes.

[0036] Figure 3 The radiation response of the two-dimensional beam scanning antenna of the application in the xoz plane at two high-low critical frequency points, in two electrically adjustable modes, is shown. In the electrically adjustable mode 1, the radiation beam is always directed to the x>0 region; in the electrically adjustable mode 2, the radiation beam is always directed to the x<0 region. It is verified that the beam switching of the embodiment of the application in the x-z plane is realized through the electrically adjustable mode.

[0037] Figure 4 The normalized radiation patterns of the two-dimensional beam scanning antenna of the application in the xoy plane at four typical frequency points, in two electrically adjustable modes, are shown. θ =90 ° The normalized radiation patterns of the two-dimensional beam scanning antenna of the application in the xoy plane at four typical frequency points, in two electrically adjustable modes, are shown. ° The normalized radiation patterns of the two-dimensional beam scanning antenna of the application in the xoy plane at four typical frequency points, in two electrically adjustable modes, are shown. ° In the mode 1, with the increase of the working frequency, the radiation beam is gradually scanned from -8 ° to 26 ° ; in the mode 2, with the increase of the working frequency, the radiation beam is gradually scanned from -172 to 154

[0001] .

[0038] Figure 5 The peak gain curves of the two-dimensional beam scanning antenna of the application in the two electrically adjustable modes are shown in FIG. Figure 5 The vertical axis is peak gain (dBi), and the horizontal axis is frequency (GHz). Due to the fact that the antenna structure is not completely symmetrical, the peak gain curves of the mode 1 and the mode 2 are not completely coincident, but the variation trend of the peak gain with frequency is basically consistent in the two electrically adjustable modes, and the peak gain in the working frequency band floats in the range of 3.5dBi to 7.3dBi.

[0039] It is concluded that the embodiment of the application realizes effective two-dimensional beam scanning through the combination of the frequency adjustment and the electric signal adjustment. Figures 2-5 The above-described specific embodiments have described the technical solutions and beneficial effects of the application in detail, and it should be understood that the above-described embodiments are the most preferred embodiments of the application, and are not used to limit the application, and any modification, supplement and equivalent replacement made within the principle range of the application should be included in the protection range of the application.

Claims

1. A two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation, characterized in that, include: At least two periodic units arranged on a substrate and cascaded along the wave propagation direction; Each periodic unit includes a leaky wave antenna module arranged along the wave propagation direction, which utilizes the dispersion effect of the leaky wave antenna to achieve one-dimensional beam scanning in the wave propagation direction based on frequency adjustment; Each periodic unit also includes electrically adjustable pattern reconfigurable modules arranged in a direction orthogonal to the wave propagation direction, which achieve another-dimensional beam scanning in the orthogonal direction based on electrical signal adjustment.

2. The two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation according to claim 1, characterized in that, The leaky antenna module includes a section of meandering parallel double line, a pair of wide microstrip lines connected to the meandering parallel double line, and a pair of microstrip stubs connected to the meandering parallel double line and extending in opposite directions.

3. The two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation according to claim 2, characterized in that, The meandering parallel double lines are printed on the upper and lower surfaces of the substrate as upper and lower supports. The current amplitudes of the upper and lower supports are the same but the phases are opposite. They only transmit signals and do not generate radiation.

4. The two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation according to claim 2, characterized in that, The pair of wide microstrip lines are printed on the upper surface of the substrate and are symmetrical about the central axis of the unit. They provide current polarization components along the wave propagation direction and introduce periodic perturbations to form a periodic leaky antenna, thereby enabling one-dimensional beam scanning as the frequency changes.

5. The two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation according to claim 2, characterized in that, The microstrip stubs are disposed on the lower surface of the substrate to compensate for the phase difference change between the upper and lower branches of the meandering parallel double line caused by the loading of the wide microstrip line, so that the upper and lower branches of the meandering parallel double line are restored to an opposite phase relationship.

6. The two-dimensional beam scanning antenna based on frequency adjustment and electronic modulation according to claim 1, characterized in that, The electrically tunable pattern reconfigurable module includes two pairs of semi-circular microstrip lines. Each pair of semi-circular microstrip lines includes two semi-circular microstrip lines. The upper and lower branches of the semi-circular microstrip lines are respectively arranged on the upper and lower surfaces of the substrate. The two pairs of semi-circular microstrip lines are mirror-symmetrical about the wave propagation direction. Each pair of semi-circular microstrip lines has a metal through-hole at the end, which connects each pair of upper and lower semi-circular microstrip lines. Each pair of semi-circular microstrip lines is connected to a pair of connecting microstrip lines by meandering parallel double lines.

7. The two-dimensional beam scanning antenna based on frequency adjustment and electronic modulation according to claim 6, characterized in that, Each pair of connected microstrip lines is equipped with a PIN diode, and the on / off state of each PIN diode is controlled by different control voltages to control the excitation state of the semi-ring microstrip line, thereby forming different radiation responses and realizing beam scanning in orthogonal directions.

8. The two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation according to claim 1, characterized in that, The periodic elements at the beginning and end are also equipped with adapters. The adapter at the beginning feeds the entire antenna, while the adapter at the end connects to a standard load to absorb the remaining energy and prevent the remaining energy from returning to the feed end and damaging the radiation performance.

9. The two-dimensional beam scanning antenna based on frequency adjustment and electrical modulation according to claim 8, characterized in that, The adapter includes an SMA connector.

Images