A method for estimating the direction of arrival of a wave in a large spaced uniform array

Abstract

The application discloses a method for estimating the direction of arrival of a large-interval uniform array, which comprises the following steps: when the DOA estimation of a target signal is performed, a double linear polarization antenna array which is uniformly arranged and has a subarray interval greater than half a wavelength is used to receive an incident signal; one unit in each subarray of the antenna array is randomly selected and its polarization state is changed; the antenna array after the polarization states of several units are changed is used to receive the original incident signal; and then, the DOA estimation is performed, so that the phase ambiguity can be effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of digital signal processing, and in particular to a method for estimating the direction of arrival of a large-pitch uniform array. Background Technology

[0002] In direction of arrival (DOA) estimation, array antennas are typically used to receive the incident signal. However, when the array is uniformly arranged and the spacing between adjacent elements is greater than half the wavelength of the incident signal, the DOA estimation results often exhibit phase ambiguity. For example, in a uniform antenna array employing a subarray-level architecture, the spacing between subarrays is usually greater than half the wavelength. Directly using this array to receive the incident signal and perform DOA estimation will often result in an incorrect indication of the direction of arrival of the incident signal due to phase ambiguity.

[0003] How to achieve unambiguous DOA estimation on such a uniformly arranged antenna array with subarray spacing greater than half a wavelength has become a problem to be solved. Summary of the Invention

[0004] To address the problems mentioned in the background art, this invention aims to provide a method for estimating the direction of arrival (DOA) of a large-spacing uniform array. The method proposed in this invention can achieve unambiguous DOA estimation on a uniformly arranged dual-polarized antenna array with a subarray spacing greater than half a wavelength. Furthermore, this method utilizes the switchable polarization characteristic of the dual-polarized antenna elements themselves, without altering the original radiation structure of the array.

[0005] To achieve the above objectives, the present invention provides a method for estimating the direction of arrival of a large-spaced uniform array, the method comprising:

[0006] Step S1: Randomly select a cell in each subarray of the antenna array, change its polarization state, and use the array to receive far-field narrowband incident signals;

[0007] Step S2: After sampling the array received signal, perform DOA estimation to obtain the direction of arrival of the incident signal.

[0008] Furthermore, in step S1, the antenna array is composed of antenna elements that can freely switch between two mutually orthogonal linear polarization states. The elements are evenly arranged, and some elements share a channel. That is, the entire array is a subarray architecture with a subarray spacing greater than half a wavelength. All subarrays are completely identical and evenly arranged.

[0009] Furthermore, in step S1, a unit is randomly selected in each subarray of the antenna array, and its linear polarization direction is changed to the cross polarization direction of the original linear polarization. The polarization state of the remaining units in the subarray remains unchanged, thereby increasing the independence of the received signals between each subarray, and the array is used to receive far-field narrowband incident signals.

[0010] Furthermore, in step S2, the analog signal received by the array after changing the polarization state of several units is sampled, and then the DOA of the incident signal is estimated using a DOA estimation algorithm. Attached Figure Description

[0011] Figure 1 This is a flowchart illustrating a specific embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of a dual-polarized antenna array in a specific embodiment of the present invention;

[0013] Figure 3 This is a schematic diagram comparing the spatial spectrum of the MUSIC algorithm in a specific embodiment of the present invention when the polarization state of the unit is not changed and when the polarization state of each subarray is changed by one unit.

[0014] Figure 4 This is a schematic diagram of the selected unit when randomly selecting a unit in each subarray to change its polarization state in a specific embodiment of the present invention. Detailed Implementation

[0015] The objectives, processes, and advantages of this invention will be further explained below with reference to specific implementation examples and accompanying drawings. It should be understood that the embodiments described herein are merely partial and exemplary, intended to explain the invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0016] Figure 2The diagram shows a 4×4 arrangement of a 16-element, 4-subarray PIN diode switch-controlled dual-polarized patch antenna array. The element spacing is half a wavelength, and the subarray spacing is one wavelength. Each element in the array has a PIN diode switch in both the x and y directions, as shown in the diagram as PIN Switch 1 and PIN Switch 2. When PIN Switch 1 is closed and PIN Switch 2 is open, each element exhibits linear polarization along the x direction (hereinafter referred to as x-polarization), and the entire array is x-polarized. When PIN Switch 1 is open and PIN Switch 2 is closed, each element exhibits linear polarization along the y direction (hereinafter referred to as y-polarization), and the entire array is y-polarized. The correspondence between the switch on / off states and the element polarization states is summarized in Table 1.

[0017] Table 1

[0018]

[0019] This embodiment provides a method for estimating the direction of arrival of a large-spaced uniform array, the method comprising:

[0020] according to Figure 2 The coordinates shown indicate that a narrowband x-polarized plane wave with a signal-to-noise ratio of 30 dB is incident from the yoz plane along a direction of θ = 35° (θ is the angle between the signal incident direction and the positive z-axis). Figure 2 The antenna array shown is configured such that, in order to ensure good signal reception, the unit switch states of the array are all set to PIN Switch 1 closed and PIN Switch 2 open, that is, the entire array is x-polarized, and the four subarrays in the array receive the incident signal.

[0021] After sampling the received signal from the four subarrays at 1024 points, DOA estimation was performed using the MUSIC (Multiple Signal Classification) algorithm. The resulting MUSIC spatial spectrum image is shown below. Figure 3 As shown by the dashed line, a "pseudo-peak" appears in the -24° direction, which means that the DOA estimation result is phase-ambiguous because the subarray spacing is greater than half a wavelength.

[0022] To suppress blur, Figure 2 In each subarray of the antenna array shown, one element is randomly selected and its switching state is set to PIN Switch 1 open and PIN Switch 2 closed, that is, its polarization state is changed from x-polarization to y-polarization, as follows. Figure 4 As shown, it should be understood that Figure 4 The cell selection method shown is just one of many selection methods.

[0023] The array is used to receive the x-polarized narrowband signal incident along the θ = 35° direction, and then sampled for DOA estimation to obtain the MUSIC spatial spectrum image as shown below. Figure 3 As shown by the solid line, it can be seen that the DOA estimation result is no longer ambiguous and the incident direction of the signal can be correctly obtained.

[0024] Based on the above embodiments, it can be seen that the method proposed in this invention can achieve unambiguous DOA estimation on a dual-polarized antenna array platform with uniformly arranged subarrays and large subarray spacing. Furthermore, this method utilizes the switchable polarization characteristic of the dual-polarized antenna elements themselves, suppressing phase ambiguity without changing the original radiation structure of the array.

[0025] To reiterate, the above embodiments are merely one of many embodiments of the present invention, intended to explain the purpose, process, and advantages of the present invention, and should not be construed as limiting the present invention. Obviously, those skilled in the art, once they grasp the inventive concept proposed by the present invention, can easily make other modifications and variations to these embodiments.

[0026] For example, after mastering the ideas proposed in this invention, when performing DOA estimation after receiving target signals using a larger-scale uniformly arranged, large-pitch subarray-level dual-polarized antenna array, relevant technicians can randomly select multiple elements in each subarray to change their polarization state. This further increases the independence of received signals between subarrays and further improves the suppression effect of phase ambiguity under a large-pitch uniform array. After mastering the ideas proposed in this invention, when performing DOA estimation after receiving target signals using large-pitch polarized reconfigurable antenna arrays such as non-uniformly arranged large-pitch dual-polarized antenna arrays, uniformly / non-uniformly arranged large-pitch dual-circularly polarized antenna arrays, and uniformly / non-uniformly arranged large-pitch fully polarized antenna arrays, relevant technicians can still achieve ambiguity-free DOA estimation by changing the polarization state of several elements in the array.

[0027] Therefore, it should be understood that any technical solution that can be obtained by those skilled in the art based on the ideas and principles of this invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined in the claims of this invention.

Claims

1. A method for estimating the direction of arrival of a large-spaced uniform array, characterized in that, The method includes: Step S1: Randomly select a cell in each subarray of the antenna array, change its polarization state, and use the array to receive far-field narrowband incident signals; Step S2: After sampling the array received signal, perform DOA estimation to obtain the direction of arrival of the incident signal.

2. The method for estimating the direction of arrival of a large-spaced uniform array according to claim 1, characterized in that, In step S1, the antenna array is composed of antenna elements that can freely switch between two mutually orthogonal linear polarization states. The elements are evenly arranged, and some elements share a channel. That is, the entire array is a subarray architecture with a subarray spacing greater than half a wavelength. All subarrays are completely identical and evenly arranged.

3. The method for estimating the direction of arrival of a large-spaced uniform array according to claim 1, characterized in that, In step S1, a unit is randomly selected in each subarray of the antenna array, and its linear polarization direction is changed to the cross polarization direction of the original linear polarization. The polarization state of the remaining units in the subarray remains unchanged, thereby increasing the independence of the received signals between each subarray. The array is then used to receive far-field narrowband incident signals.

4. The method for estimating the direction of arrival of a large-spaced uniform array according to claim 1, characterized in that, In step S2, the analog signal received by the array after changing the polarization state of several units is sampled, and then the DOA of the incident signal is estimated using the DOA estimation algorithm.

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