Arbitrary elliptical polarization programmable array antenna construction method

Abstract

The invention discloses an arbitrary elliptical polarization programmable array antenna construction method. A single multi-polarization reconfigurable antenna can only realize a plurality of discrete polarization states and cannot realize receiving or transmitting of any elliptical polarization electromagnetic wave. According to the method, expected elliptical polarization is decomposed into superposition of vectors in the long axis direction and the short axis direction of an ellipse, four alternative polarization states are selected according to projection values of a multi-linear polarization reconfigurable unit in the two directions, then the number of the four alternative polarization states is calculated, and the polarization states of array units are randomly distributed according to the calculated number. And finally, receiving or transmitting any elliptical polarization electromagnetic wave according to the wave beam direction and the expected elliptical polarization configuration unit excitation phase. Polarization resources of electromagnetic waves can be fully utilized, and the method plays a significant role in expanding the capacity of a wireless electromagnetic system, improving the receiving and transmitting efficiency of the system, resisting external interference and the like.

Description

Technical Field

[0001] The present invention relates to the technology of arbitrary elliptical polarization array antennas in the fields of radar, communication, and electronic countermeasures. Background Art

[0002] The polarization of antennas is usually fixed linear polarization or circular polarization, and it is prone to polarization mismatch problems in complex polarization environments. The emerging polarization reconfigurable antennas can achieve switching between linear / circular polarization, multi-linear polarization, dual circular polarization, etc. on a single antenna. However, achieving low-cost arbitrary elliptical polarization at the array level remains an unsolved problem. Implementing this function has practical significance for making full use of the polarization dimension of electromagnetic waves and improving the performance of electromagnetic systems such as phased array radar systems, electronic countermeasure systems, and navigation and positioning systems.

[0003] The classical method to achieve arbitrary polarization adjustment is to use dual-channel dual-polarization element antennas, combined with two sets of independently controllable amplitude and phase. However, achieving arbitrary elliptical polarization with this method requires channels with continuously adjustable amplitude and phase or digital channels with small enough stepwise adjustable amplitude and phase, which will lead to a doubling of the system equipment volume and thus an increase in cost, to a certain extent restricting the popularization and application of this method.

[0004] Array antennas using polarization reconfigurable antennas as array elements can achieve polarization state switching on the premise of one antenna per radio frequency channel. However, existing research on polarization reconfigurable antenna arrays usually only combines a few polarization reconfigurable antennas into an array, and the achievable polarization states are still restricted by the polarization states of the elements themselves. In a 1×4 polarization reconfigurable array, a ±45° linear polarization reconfigurable antenna element based on a reconfigurable feeding network is used. However, its array can only achieve the polarization states of the arrayed element antennas, rather than arbitrary polarization states.

[0005] There have been studies on linear arrays with arbitrary linearly adjustable polarization and conformal arrays with arbitrary linear / circular polarization adjustable in existing literature. They both achieve the desired polarization by selecting the polarization states of the elements. However, they still have the following problems: In the linear array study, the polarization selection method is a random optimization algorithm, whose results have large randomness and slow convergence speed, and can only achieve linear polarization states; In the conformal array study, by using multi-linear polarization reconfigurable elements on the conformal array and configuring the polarization states and excitation phases, linear / circular polarization adjustment can be achieved. However, arbitrary elliptical polarization states cannot be achieved.

[0006] In summary, the prior art cannot achieve an arbitrarily elliptical polarization programmable beam at the array level with one antenna element corresponding to one radio frequency channel, that is, under low-cost conditions. Summary of the Invention

[0007] The present invention proposes a new arbitrary elliptical polarization programmable array antenna technology. By using a multi-linear polarization reconfigurable antenna as a planar array unit, arbitrary elliptical polarization beam synthesis is achieved by configuring the unit polarization state and excitation phase. The proposed arbitrary elliptical polarization programmable array antenna technology can achieve arbitrary elliptical polarization switching on a planar array without increasing the number of RF channels, can make full use of the polarization dimension of electromagnetic waves, and has broad application prospects.

[0008] The proposed arbitrary elliptical polarization programmable array antenna mainly consists of a multi-linear polarization reconfigurable planar antenna array, a unit polarization and excitation phase control network, and a polarization state and excitation phase configuration algorithm.

[0009] The polarization programmable antenna array at and The vector pattern of the component is:

[0010]

[0011] Among them, and Are respectively the and Component pattern of the nth element in the m polarization state, β is the wave number, Is the position vector of the element in the global coordinate system.

[0012] 1) Decomposition of the major and minor axis vectors of the desired elliptical polarization:

[0013] Generally speaking, the desired elliptical polarization p d Is represented by its Jones vector and can be written as:

[0014]

[0015] Among them, A x And A y Are respectively the real amplitudes in the directions of e x And e y , Is the phase difference of the e y Component relative to the e x Component. Assuming that the orientation of the major axis of the ellipse is ξ, then according to the basic knowledge of elliptical polarization, it can be obtained:

[0016]

[0017] If a coordinate system is established with the major axis direction e L And the minor axis direction e S , then in the new coordinate system, the orientation of the major axis of the ellipse θ ′ = 0°, and according to the above formula, the e S Component of the elliptical polarization relative to eL Phase difference of components Then the elliptical polarization can be written as:

[0018]

[0019] A L and A S are the real amplitudes in the directions of e L and e S respectively. According to the geometric relationship of the ellipse, A L and A S can be obtained by the following formula:

[0020]

[0021] 2) Unit polarization state and phase configuration method:

[0022] Let the electric field vectors of the unit antenna in each polarization state at (θ0, φ0) be {E n (θ0, φ0; 1), E n (θ0, φ0; 2), …, E n (θ0, φ0; n), … E n (θ0, φ0; M)}, and their orientations are uniformly distributed in the range of 0 - π. For the desired elliptical polarization p d , the projections of the radiated electric field vector of the unit in the polarization state m in the directions of e L and e S are:

[0023]

[0024] Sorted in descending order according to the obtained projection values: Proj L (m L1 ) > Proj L (m L2 ) > … > Proj L (m LM ) and Proj S (m S1 ) > Proj S (m S2 ) > … > Proj S (m SM ). At the same time, it is easy to find that (E n (θ0, φ0; m L1 ) · e S ) · (E n (θ0, φ0; m L2 ) · e S ) ≤ 0, and (E n (θ0, φ0; m S1 ) · eL )·(E n (θ0, φ0; m S2 )·e L ) ≤ 0. This means that if a part of the array elements are selected to be in m L1 and m L2 , it is expected to synthesize a vector with a higher purity in the e L direction. If a part of the array elements are selected to be in m S1 and m S2 , it is expected to synthesize a vector with a higher purity in the e S direction. Let N L1 array elements be in the m L1 state, N L2 array elements be in the m L2 state, N S1 array elements be in the m S1 state, and N S2 array elements be in the m S2 state. Then, in order to obtain vectors with the highest possible purity in the e L direction and the e S direction, the values of N L1 , N L2 , N S1 and N S2 have the following constraints:

[0025]

[0026] Among them,

[0027]

[0028] In addition, in order to make the amplitudes of the synthesized vectors in the e L direction and the e S direction as close as possible to the desired elliptical polarization, the following constraint equations can be obtained:

[0029]

[0030] At the same time, the sum of N L1 , N L2 , N S1 , N S2 should be equal to the total number of array elements. Thus:

[0031] N L1 + N L2 + N S1 + N S2 = N (13)

[0032] From the above constraint equations, N L1 , N L2 , N S1 , NS2 Value. However, there is no restriction on the specific unit polarization state distribution. The polarization state distribution of the array can be randomly configured for the units, only ensuring that the number of array elements in the m L1 , m L2 , m S1 , m S2 polarization states are respectively the calculated N L1 , N L2 , N S1 and N S2 respectively.

[0033] The array elements in the m L1 , m L2 polarization states are used to synthesize the vector field in the e L direction, while the array elements in the m S1 , m S2 polarization states are used to synthesize the vector field in the e S direction. According to Equation (5), the excitation phase of the unit can be configured:

[0034]

[0035]

[0036] where, λ is the wavelength, is the position vector of the array element, is the beam pointing vector. When the desired elliptical polarization is left-handed When the desired elliptical polarization is right-handed Beneficial effects

[0037] The arbitrary elliptical polarization programmable array antenna technology proposed by the present invention has the following beneficial effects:

[0038] 1) It can realize the transceiver of arbitrary elliptical polarization electromagnetic waves at low cost, can make full use of the polarization dimension of electromagnetic waves, and is not limited to linear polarization or circular polarization, supporting more flexible polarization matching requirements;

[0039] 2) By dynamically adjusting the polarization mode, this technology can effectively reduce the polarization mismatch loss in signal transmission and suppress multipath fading and interference;

[0040] 3) The traditional implementation of arbitrary elliptical polarization relies on dual-polarized antennas / dual-channel designs, resulting in an increase in the volume and cost of the equipment. The present invention realizes arbitrary elliptical polarization on the premise of one antenna and one radio frequency channel, and the programmable array technology significantly simplifies the hardware structure and reduces the cost through a single-channel combined with reconfigurable unit design. Description of the drawings

[0041] Figure 1Unit position arrangement of the 300-element planar array.

[0042] Figure 2 It is the main polarization distribution and cross-polarization distribution obtained when the ellipticity of the desired elliptical polarization is 0.3 and the orientation of the major axis of the ellipse is 30°.

[0043] Figure 3 It is the polarization state distribution and excitation phase configuration of the obtained 300-element planar array.

[0044] Figure 4 It is the main polarization pattern and cross-polarization pattern of the array synthesis. Detailed implementation manner

[0045] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further details the present invention with reference to specific embodiments and the appended Figures 1-4 ,.

[0046] Step 1. Select a multi-line polarization reconfigurable element antenna, construct a planar array and determine other relevant parameters. Here, we select an element antenna which is a 7-line polarization reconfigurable element antenna with a polarization state distributed in rotational symmetry. The element pattern is the same as the analytical dipole expression, and it is arranged in a plane, as Figure 1 shown.

[0047] Step 2. Decompose the desired elliptical polarization into the superposition of the major axis component and the minor axis component of the ellipse. Assume that the ellipticity of the desired polarization is 0.3 and the orientation of the major axis of the ellipse is 30°. Figure 2 Shown is the desired elliptical polarization and the distribution of its corresponding main polarization and cross-polarization components in space.

[0048] Step 3. Adopt the proposed element polarization state selection and excitation phase configuration method to calculate the required element polarization states and excitation phases; Figure 3 Shown is the polarization state and excitation phase distribution obtained by the 300-element array when the desired polarization is the above-mentioned elliptical polarization and the beam pointing is (0°, 0°). Figure 4 They are the main polarization and cross-polarization beams of the obtained array.

[0049] Step 4. Process the array and design a DC bias network to electronically control the polarization state of the elements. Together with a control chip such as an FPGA or a single-chip microcomputer, an array antenna with arbitrary elliptical polarization programmability can be realized.

[0050] The specific embodiments described above further elaborate on the object, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of the present invention.

Claims

1. A method for constructing an arbitrary elliptical polarization programmable array antenna, characterized in that The steps include the following: S1: Establish an array model: construct a multi-line polarization reconfigurable planar antenna array and determine other relevant parameters, including the number of reconfigurable polarizations of antenna element discreteness, element pattern, element antenna structure, number of array elements, and array layout; S2: Decompose the desired elliptical polarization into the superposition of the major axis component and the minor axis component of the ellipse according to the user's expectation; S3: Adopt the proposed method for selecting the polarization state of the array element and configuring the excitation phase to calculate the required polarization state and excitation phase of the element; S4: Process the array antenna, design the DC bias network and phase shifter network, and then cooperate with the field programmable gate array FPGA or single-chip microcomputer control chip to electrically control the polarization state and excitation phase of the array element in real time.

2. The method for constructing an arbitrarily polarized electromagnetic wave generator according to claim 1, wherein: The element antenna used in the array arrangement in step S1 is a multi-line polarization reconfigurable antenna with a rotationally symmetric distribution of polarization states, and the array form is a planar array.

3. The method for constructing an arbitrarily polarized electromagnetic wave generator according to claim 1, wherein: In step S2 shown, for the desired elliptical polarization given by the user, use to represent, where e L and e S are the unit vectors in the directions of the major axis and minor axis of the desired elliptical polarization respectively, A L , A S are the amplitudes of the desired elliptical polarization in the directions of e L and e S respectively, and are the phases of the desired elliptical polarization in the directions of e L and e S respectively. Among them, and the difference between them satisfies the following equation:

4. The construction method of an arbitrarily polarized electromagnetic wave generator according to claim 1, characterized in that: When the desired polarization in step S3 is a general elliptical polarization, the specific steps are as follows: S3.1 When performing polarization selection, first calculate the values of the radiation field vectors of the element in different polarization states projected onto the major axis direction and the minor axis direction of the desired elliptical polarization: Among them, E n (θ0, φ0; m) is the radiation field vector of the nth unit in the m polarization state in the (θ0, φ0) direction. According to Proj L (m) and Proj S (m), the polarization states are sorted from large to small values. The polarization states ranked in the top two for Proj L (m) are denoted as m L1 and m L2 . The polarization states ranked in the top two for Proj S (m) are denoted as m S1 and m S2 . Let N L1 array elements be in the m L1 state, N L2 array elements be in the m L2 state, N S1 array elements be in the m S1 state, N S2 array elements be in the m S2 state; S3.2 N L1 , N L2 , N S1 and N S2 The values of are calculated from the following system of equations: N L1 +N L2 +N S1 +N S2 = N(6) where, N is the total number of array elements, and N is calculated and obtained. L1 , N L2 , N S1 and N S2 After that, randomly assign the polarization state distribution of the array configuration units, only ensuring that the number of array elements in the polarization states of m L1 , m L2 , m S1 , m S2 are respectively the calculated N L1 , N L2 , N S1 and N S2 That's all. S3.3 According to the beam direction and the obtained element polarization state distribution, configure the excitation phase for the array element according to the following equation: wherein, λ is the wavelength, is the array element position vector, is the beam pointing vector.

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