Dual-polarized and pattern-reconfigurable wideband vector array antenna for three-dimensional direction finding

Abstract

The application discloses a dual-polarization and pattern-reconfigurable wideband vector array antenna for three-dimensional direction finding, and belongs to the technical field of array antennas. The antenna comprises two two-dimensional vector antennas and a circular array, the two two-dimensional vector antennas are perpendicular to each other and are vertically arranged on the circular array, and the circular array comprises eight radial Vivaldi antennas which are uniformly distributed around the same center in a horizontal plane. The eight Vivaldi antennas replace the metal supports of the two two-dimensional vector antennas, serve as the ground planes of the two two-dimensional vector antennas, and serve as electromagnetic sensors for measuring three components Hz, Ex and Ey. The two two-dimensional vector antennas and the circular array form a four-dimensional vector antenna. The antenna can realize accurate estimation of the wave direction of a vertically or horizontally polarized incident electromagnetic signal in a wider bandwidth of more than 7:1.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of array antennas, and particularly relates to a dual-polarized and pattern reconfigurable wideband vector array antenna for three-dimensional direction finding. BACKGROUND

[0002] Direction finding of incident electromagnetic wave signals is applied in many civil and military radio navigation or radio positioning related fields. Most direction finding antennas are wideband and estimate the direction of arrival of incident electromagnetic fields in a two-dimensional angular coverage, i.e. only the azimuth angle in a limited elevation angle range. Direction of arrival estimation usually relies on the spatial diversity of an antenna array. This can require three-dimensional angular coverage, i.e. estimation of the azimuth angle and the elevation angle. With direction finding technology of vector antennas, such coverage can be achieved regardless of the polarization of the incident electromagnetic field. Ideally, a vector antenna can measure six components of the incident electromagnetic signal (i.e. Ex, Ey, Ez, Hx, Hy and Hz in the Cartesian coordinate system), thereby performing direction of arrival estimation in three-dimensional space.

[0003] However, existing antennas cannot achieve accurate estimation of the direction of arrival of vertically or horizontally polarized incident electromagnetic signals in a wider bandwidth. SUMMARY

[0004] Therefore, the present application provides a dual-polarized and pattern reconfigurable wideband vector array antenna for three-dimensional direction finding, which can achieve accurate estimation of the direction of arrival of vertically or horizontally polarized incident electromagnetic signals in a wider bandwidth of more than 7:1.

[0005] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0006] A dual-polarized and pattern reconfigurable wideband vector array antenna for three-dimensional direction finding comprises two two-dimensional vector antennas and a circular array, the two two-dimensional vector antennas are orthogonal to each other and are vertically arranged on the circular array, the circular array comprises eight radial Vivaldi antennas uniformly distributed around the same center in the horizontal plane; the eight Vivaldi antennas replace the metal supports of the two two-dimensional vector antennas, serve as the ground plane of the two two-dimensional vector antennas, and serve as electromagnetic sensors for measuring three components Hz, Ex and Ey; the two two-dimensional vector antennas and the circular array constitute a four-dimensional vector antenna.

[0007] Further, the two-dimensional vector antenna is a semicircular array, and the circular array is a 1.5-fold replication of the semicircular array of the two-dimensional vector antenna.

[0008] Further, the feeding circuit includes a 1:2 microstrip power divider, and the 1:2 microstrip power divider includes two 100-ohm impedance transition lines connected by a T-junction, and the combined impedance transition lines are connected to a 50-ohm input port.

[0009] Further, the measurements of the electromagnetic field components Hx, Hy and Ez are obtained from three sets of weighting coefficients assigned to the received signals at the vertical ports of the two-dimensional vector antenna, in particular:

[0010] According to the mirror symmetry between the two feeding circuits of the two-port vertical array, when the two symmetric ports are out of phase, the four Vivaldi antennas are excited in phase to form a magnetic dipole by applying the weighting coefficients [1, -1], so as to measure the Hx component and the Hy component;

[0011] By applying the weighting coefficients [1, 1, 1, 1], all the ports of the vertical part of the vector antenna are recombined in phase to form an electric dipole oriented along the z-axis, so as to measure the Ez component.

[0012] The present application has the following advantages:

[0013] 1. The antenna structure is simple and easy to manufacture.

[0014] 2. The antenna structure is simple and easy to manufacture.

[0015] 3. The antenna can measure six components of the incident electromagnetic signal, and can realize accurate estimation of the wave arrival direction of the vertically or horizontally polarized incident electromagnetic signal in a wider bandwidth of more than 7:1. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The structure of the wideband vector array antenna of the embodiment of the present application is shown.

[0017] Figure 2 The port diagram of the wideband vector array antenna of the embodiment of the present application is shown.

[0018] Figure 3 The front view of the circular array in the embodiment of the present application is shown.

[0019] Figure 4 The back view of the circular array in the embodiment of the present application is shown.

[0020] Figure 5A structure schematic diagram of a two-dimensional vector antenna in the embodiment of the present application.

[0021] Figure 6 A schematic diagram of a feeding circuit in the embodiment of the present application. DETAILED DESCRIPTION

[0022] The present application will be further described in detail below with reference to the accompanying drawings.

[0023] As Figures 1-4 shown, a dual-polarization and pattern-reconfigurable wideband vector array antenna for three-dimensional direction finding includes two two-dimensional vector antennas and a circular array, the two two-dimensional vector antennas are orthogonal to each other and vertically arranged on the circular array, the circular array includes eight radial Vivaldi antennas uniformly distributed around the same center in the horizontal plane, the ports of the eight Vivaldi antennas are Port 1-Port 8 respectively; the eight Vivaldi antennas replace the metal support of the two two-dimensional vector antennas, serve as the ground plane of the two two-dimensional vector antennas, and serve as electromagnetic sensors for measuring three components Hz, Ex and Ey; the two two-dimensional vector antennas and the circular array constitute a four-dimensional vector antenna.

[0024] As Figure 5 shown, the two-dimensional vector antenna is a semicircular array, and the circular array is a 1.5 times replication of the semicircular array of the two-dimensional vector antenna.

[0025] When the antenna is connected inside the antenna array, the input impedance of the Vivaldi antenna is about 100Ω instead of 65Ω. For this reason, the power divider part of the wideband vector array antenna feeding circuit uses a 1:2 microstrip line power divider. As Figure 6 shown, the 1:2 microstrip line power divider includes a T-junction and an impedance transition line, and is connected to a 50Ω input port, the microstrip line power divider can be conveniently realized by two 100Ω microstrip lines. This feeding circuit has a wider impedance bandwidth.

[0026] The present antenna can estimate the direction of arrival of the incident horizontally polarized electromagnetic signal, and reduce the estimation error caused by polarization mismatch. The wideband vector array antenna can measure six components of the incident electromagnetic signal, specifically, the measurement of electromagnetic field components Hx, Hy and Ez is from three sets of weighting coefficients (represented by the acronym RPC 0, which stands for radiation pattern combination 0) assigned to the received signals at the vertical ports of the vector antenna.

[0027] According to the mirror symmetry between the two feed circuits of the two-port vertical array, when ports 1 and 2 (or ports 3 and 4) are out of phase, the Hx component and the Hy component can be measured by applying the weighting coefficients [1, -1] to excite the four Vivaldi antennas in phase to form a magnetic dipole.

[0028] The Ez component can be measured by applying the weighting coefficients [1, 1, 1, 1] to recombine all the ports of the vertical part of the vector antenna in phase to form an electric dipole oriented along the z-axis.

[0029] The other three components Hz, Ex, and Ey can also be derived from the other three sets of weighting coefficients assigned to the received signals of the horizontal ports of the vector antenna.

[0030] Likewise, according to the mirror symmetry between the feed structures of two adjacent Vivaldi antennas, if the eight Vivaldi antennas of the horizontal array are fed in phase to act as a magnetic dipole, this can be achieved by applying [1, -1, 1, -1] on ports 5-8. The Ex component is measured by recombining the ports of the horizontal part of the vector antenna (weighting coefficients [1, -1, -1, 1]) to create a magnetic wall along the XZ plane and an electric wall along the YZ plane (or XZ plane), forming an electric dipole oriented along the x-axis (or y-axis).

[0031] The weighting coefficients related to the measurement of the six electromagnetic field components are summarized in the following table:

[0032]

[0033] In summary, the present invention achieves a four-dimensional vector antenna by modifying the feed circuit of the vector antenna and using a four-port circular array as a horizontal electromagnetic sensor. Compared with the existing four-port two-dimensional vector antenna, the invented antenna is able to perform direction of arrival estimation on the incident electromagnetic signal over a wider bandwidth (7:1 or [1-7 GHz]) regardless of its polarization. Although the feed circuit of the present invention has eight ports, the accuracy of the DoA estimation of the vertical polarization of the incident electromagnetic signal is improved due to the measurement of the horizontal components (Ex, Ey, and Hz).

Claims

1. A dual-polarized and pattern-reconfigurable wideband vector array antenna for three-dimensional direction finding, characterized in that, The four-dimensional vector antenna comprises two two-dimensional vector antennas and a circular array, the two two-dimensional vector antennas are perpendicular to each other and are arranged vertically on the circular array, and the circular array comprises eight radial Vivaldi antennas uniformly distributed around the same center in the horizontal plane; eight Vivaldi antennas replace the metal supports of the two two-dimensional vector antennas, serve as the ground plane of the two two-dimensional vector antennas, and serve as electromagnetic sensors for measuring Hz, Ex and Ey three components; the two two-dimensional vector antennas and the circular array constitute the four-dimensional vector antenna; The two-dimensional vector antenna is a semicircular array, and the circular array is a 1.5-fold replication of the semicircular array of the two-dimensional vector antenna; The feeding circuit further comprises a 1:2 microstrip power divider, and the 1:2 microstrip power divider comprises two 100Ω impedance transition lines connected through a T junction, and the combined impedance transition line is connected to a 50Ω input port.

2. The dual-polarization and pattern-reconfigurable wideband vector array antenna for 3D direction finding of claim 1, wherein, The measurement of the electromagnetic field components Hx, Hy and Ez is realized by three sets of weighting coefficients assigned to the received signals at the vertical ports of the two-dimensional vector antenna, in particular: According to the mirror symmetry between the two feeding circuits of the two-port vertical array, when the two symmetric ports are out of phase, four Vivaldi antennas are excited in phase to form a magnetic dipole by applying the weighting coefficient [1, -1], so as to measure the Hx component and the Hy component; By applying the weighting coefficient [1, 1, 1, 1], all the ports of the vertical part of the vector antenna are recombined in phase to form an electric dipole oriented along the z axis, so as to measure the Ez component.

Images