A method for arraying elements of a conformal array antenna

Abstract

This invention discloses a method for arraying elements of a conformal array antenna, relating to the field of conformal phased array antenna technology. The method includes the following steps: element spacing design; using dual-polarized symmetrical array elements for the linear units; designing the spherical conformal antenna array as M layers; and generating an isotropic omnidirectional radiation pattern in the upper hemisphere by feeding all elements in the spherical conformal antenna array with equal amplitude and in-phase power. This method provides a simple and regular array manifold design for large spherical phased array antenna applications, and also provides a method for generating an isotropic omnidirectional radiation pattern in the upper hemisphere under equal amplitude and in-phase feeding of elements. The conformal array antenna features full spatial coverage, wide beam pattern uniformity with small gain fluctuations, high equivalent omnidirectional radiated power, and flexible control over radiation direction and bandwidth.

Description

Technical Field

[0001] This invention relates to the field of conformal phased array antenna technology, specifically to a method for arranging the array elements of a conformal array antenna. Background Technology

[0002] An antenna is a transducer that transforms guided waves propagating on a transmission line into electromagnetic waves propagating in an unbounded medium (usually free space), or vice versa. It's a component in wireless equipment used to transmit or receive electromagnetic waves. Engineering systems such as radio communication, broadcasting, television, radar, navigation, electronic countermeasures, remote sensing, and radio astronomy—anything that uses electromagnetic waves to transmit information—rely on antennas. Furthermore, antennas are also needed for non-signal energy radiation in the transmission of energy using electromagnetic waves. Generally, antennas are reversible, meaning the same antenna can be used as both a transmitting and receiving antenna. The fundamental characteristic parameters of the same antenna are identical whether it's used for transmitting or receiving. This is the reciprocity theorem of antennas.

[0003] In the current technology, with the development of the phased array field, forming a flat and uniform ultra-wide beam omnidirectional pattern across the entire spatial domain is an important issue facing the phased array field. Conformal array antennas have the characteristics of covering the entire spatial domain, uniform wide beam pattern with small gain fluctuation, high equivalent omnidirectional radiation power, and flexible control of radiation direction and beamwidth. Moreover, they have the advantages of high system fault tolerance and easy monitoring and maintenance, making them a good choice for a combination of omnidirectional and ultra-wide beam pattern. In view of this, we propose an array element arrangement method for conformal array antennas. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for arranging array elements of a conformal array antenna, which solves the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for arranging the elements of a conformal array antenna, the method comprising the following steps:

[0006] S1, element spacing according to Left-right design;

[0007] S2. The antenna element adopts a dual-polarization symmetrical array to achieve two rotation directions of circular polarization pattern;

[0008] S3, the spherical conformal antenna array is designed with M layers;

[0009] S4. By feeding all elements in the spherical conformal antenna array with equal amplitude and phase, an isotropic omnidirectional radiation pattern in the upper hemisphere is generated. Feeding some adjacent elements with equal amplitude and phase can generate ultra-wide beam patterns with multiple angular pointing and multiple angular coverage ranges.

[0010] The array element arrangement is designed according to the following principles:

[0011] T1. Based on the size of the sphere, starting from the first array element at the zenith, considering the condition that the array element spacing d is satisfied, the number of layers that need to be designed can cover the upper hemisphere. Determine the number and angle of array element replication along the meridian of 1 / 4 of the sphere, and at the same time determine the starting unit position of each layer of array.

[0012] T2. The primary principle of each layer of array is to approximate the unit spacing d after completing one circle of latitude layer. After determining the unit spacing d1 and the number of units N1 for each layer, the array of that layer starts with one unit and performs a rotational copy along the Z-axis with a rotation angle of 360° / N1 to obtain the rotational copy position of the second unit.

[0013] T3, based on the two principles in T1 and T2, can serve as the design basis for all given frequency bands, different array element designs, and different sizes of spherical conformal arrays.

[0014] Optionally, the antenna layout manifold along the 1 / 4 spherical meridian in T1 is arranged as follows: based on a single array element at the zenith, it is rotated and replicated along the X-axis or Y-axis, with a rotation angle of 90° / M.

[0015] Optionally, T2 further includes: the second unit should then rotate along the sphere based on the copied position, with a rotation angle of 360° / N1, and so on. The third unit of the layer completes the layout by performing the above operation based on the second unit. The above principle can complete the layout manifold of all units in the layer.

[0016] Optionally, the λ min It is calculated from the highest frequency point of the broadband unit, and θ is taken as 60°.

[0017] Optionally, S1 further includes: for a given operating frequency band and maximum scanning angle θ, the element spacing to ensure no grating lobes appear at the maximum scanning angle, based on phased array antenna theory, is given by the following formula:

[0018] Optionally, the antenna element is right-hand circularly polarized, with the propagation direction along the positive z-axis, and the circularly polarized wave is propagated along... direction and Description of the two linear polarization components in the direction:

[0019]

[0020] ω is the angular frequency, t is time, and z is the electromagnetic wave propagation distance.

[0021] Optionally, the antenna element is rotated counterclockwise by τ around the z-axis, and after rotation, the circularly polarized wave is used... This indicates a coordinate rotation diagram. and The relationship is as follows:

[0022]

[0023]

[0024]

[0025] The circularly polarized wave E1 of the rotated antenna element can be expressed as:

[0026]

[0027] If the second array element is rotated 180° and placed opposite the other two array elements, the superposition of the electric fields pointing to (0°, 0°) of the two array elements can be expressed as:

[0028]

[0029] Optionally, rotating the antenna element radiating right-hand circularly polarized waves counterclockwise around the z-axis by an angle τ is equivalent to adding a phase shift -τ to the antenna element feed. When τ is π, E+E1 cancel each other out to 0.

[0030] This invention provides a method for arranging the elements of a conformal array antenna. It has the following beneficial effects:

[0031] 1. The array element arrangement method of this conformal array antenna provides a simple and regular array manifold design for the application of large spherical phased array antennas. At the same time, it provides a method for forming an isotropic omnidirectional radiation pattern in the upper hemisphere under equal amplitude and in-phase feeding of array elements for large spherical phased array antennas. The conformal array antenna has the characteristics of covering the entire space domain, uniform wide beam pattern with small gain fluctuation, high equivalent omnidirectional radiation power, and flexible control of radiation direction and beamwidth. It solves the problem of zero depth of gain in the zenith direction of traditional spherical and cylindrical arrays.

[0032] 2. The array element arrangement method of this conformal array antenna provides a method for forming an ultra-wide beam pattern with an isotropic omnidirectional radiation pattern in the upper hemisphere and multiple angular pointing and coverage ranges for large conformal phased array antennas, with a gain fluctuation of 2dB in the upper hemisphere omnidirectional radiation pattern. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the element distribution of the spherical phased array antenna of the present invention;

[0034] Figure 2 This is a three-dimensional schematic diagram of the spherical phased array antenna of the present invention;

[0035] Figure 3 This is a top view schematic diagram of the spherical phased array antenna of the present invention;

[0036] Figure 4 This is a schematic diagram of the array element rotation of the present invention;

[0037] Figure 5 This is a schematic diagram of a directional wide beam generated by equal-amplitude and in-phase feeding of some adjacent array elements in an embodiment of the present invention;

[0038] Figure 6 This is a 3D radiation pattern of a directional wide beam within the angle range selection area of ​​the present invention;

[0039] Figure 7 This is a 2D radiation pattern of a directional wide beam within the angle range selection area of ​​the present invention;

[0040] Figure 8 This is a schematic diagram of the gain fluctuation in the omnidirectional radiation pattern simulation of the array antenna of the present invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Please see Figures 1-8 This invention provides a technical solution: a method for arranging the elements of a conformal array antenna, comprising the following steps:

[0043] S1, element spacing according to Left and right design, λ min Calculated from the highest frequency point of the broadband unit, θ is taken as 60°;

[0044] For a given operating frequency band and maximum scanning angle θ, the element spacing to ensure no grating lobes appear at the maximum scanning angle, according to phased array antenna theory, is given by the following formula:

[0045]

[0046] Viewed from the top, this design can be approximated as laying a planar array with equal element spacing on the upper hemisphere. Since the elements surrounding each element are equally spaced and arranged at a small angle on the upper hemisphere, a nearly isotropic radiation pattern is formed, solving the problem of zero depth gain in the zenith direction of traditional spherical and cylindrical arrays. Viewed from the side, this design can be understood as follows: this conformal array is no longer simply a traditional conformal array design where each layer of elements is merely rotated and copied along the Z-axis. Instead, each element, while being rotated and copied along the Z-axis, also rotates along the line connecting to the center of the sphere. The angle of rotation is equal to the rotational copying angle of that layer based on one element copied to the target location.

[0047] Since the elements of traditional spherical and cylindrical phased array antennas are not on the same plane and have different polarization directions, the non-co-polarization problem of the spherical phased array antenna elements needs to be considered. When the electric field vectors of the far-field electromagnetic waves emitted by different elements have the same polarization direction, polarization matching occurs, and the electric field vectors are in a superposition state, which is the optimal transmission state. However, traditional spherical array antennas suffer from non-co-polarization, causing the electric field vectors in the zenith direction to cancel each other out, resulting in a degraded antenna performance. The purpose of this design is to solve the problem of polarization cancellation in the zenith direction of the radiation pattern of traditional spherical and cylindrical arrays.

[0048] To understand the effect of this design using electromagnetic field theory, consider two rotating replica positions located at a certain layer with a Z-axis angle of 180°.

[0049] The antenna element is right-hand circularly polarized, and the propagation direction is the positive z-axis. This circularly polarized wave can be used along... direction and Description of the two linear polarization components in the direction:

[0050]

[0051] In the formula, ω is the angular frequency, t is the time, and z is the electromagnetic wave propagation distance.

[0052] Rotate the antenna element counterclockwise by τ around the z-axis. After rotation, the circularly polarized wave is used... express.

[0053] Coordinate rotation diagram and The relationship is as follows:

[0054]

[0055]

[0056]

[0057] The circularly polarized wave E1 of the rotated antenna element can be expressed as:

[0058]

[0059] If the second array element is rotated 180° and placed opposite the other two array elements, the superposition of the electric fields pointing to (0°, 0°) of the two array elements can be expressed as:

[0060]

[0061] As can be seen from the formula, rotating the antenna element radiating right-hand circularly polarized waves counterclockwise around the z-axis by an angle τ is equivalent to adding a phase shift of -τ to the antenna element feed. When τ takes the value of π (i.e., the second element at the 180° rotation position), according to Euler's formula, E+E1 cancel each other out to 0.

[0062] The design aims to avoid the effects of polarization cancellation caused by the alignment (180° phase difference in rotation replication) of two array elements. This can be achieved by compensating the second array element with a corresponding rotation angle (180°) using a phase compensation method. The unit physical rotation method proposed in this design can avoid polarization cancellation by rotating the unit around the axis connected to the center of the sphere by 180° (that is, the rotation angle is equal to the rotation replication angle of the layer based on one array element to the target position, which is generally τ angle). There is no need to configure different phases for different units. This can also improve the zenith pit of the radiation pattern by achieving equal amplitude and phase feeding for all array elements.

[0063] S2. The antenna element adopts a dual-polarized symmetrical array, which can realize two rotation directions of circular polarization pattern.

[0064] S3, the spherical conformal antenna array is designed with M layers;

[0065] The above-mentioned array element arrangement follows the array arrangement principle, which is as follows for each layer:

[0066] T1. Based on the spherical size, starting from the first array element at the zenith, how many layers (M) are needed to cover the upper hemisphere while satisfying the element spacing d? This determines the number and angle of array element replication along the quarter-spherical meridian, and also determines the starting element position of each layer (latitude). The antenna layout manifold along the quarter-spherical meridian is arranged according to the following principle: starting from one array element at the zenith, it is rotated and replicated along the X-axis or Y-axis at a rotation angle of 90° / M. This completes the array layout along the quarter-spherical meridian, and also determines the starting element position of each layer.

[0067] T2. The primary principle for arranging each layer (latitude) is that after completing one circle of latitude layer, the unit spacing should be approximately d. Since the diameter of the circle varies in each layer, it is not required to precisely maintain the unit spacing d; the absolute value of the positive or negative difference of the spacing d should be taken as the smallest. Specifically, the arrangement method for each layer is as follows: after determining the unit spacing d1 and the number of units N1 for that layer, the arrangement starts with one unit and performs a rotational replication along the Z-axis at a rotation angle of 360° / N1. This yields the rotational replication position of the second unit. The second unit should then rotate along the sphere from this replication position, also at a rotation angle of 360° / N1. This process continues for the third unit in the layer, completing the layout by performing the same operations on the second unit. These principles can complete the layout manifold for all units in that layer.

[0068] T3. The above two principles can serve as the design basis for all given frequency bands, different array element designs, and different sizes of spherical conformal arrays.

[0069] S4. By feeding all elements in a spherical conformal antenna array with equal amplitude and phase, an isotropic omnidirectional radiation pattern in the upper hemisphere (i.e., phi range 0°-360°, theta range 0°-90°) can be generated. Feeding some adjacent elements with equal amplitude and phase can generate ultra-wide beam patterns with multiple angular pointing and multiple angular coverage ranges.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for arranging the elements of a conformal array antenna, characterized in that: The array arrangement method includes the following steps: S1, element spacing according to Left-right design; S2. The antenna element adopts a dual-polarization symmetrical array to achieve two rotation directions of circular polarization pattern; S3, the spherical conformal antenna array is designed with M layers; S4. By feeding all elements in the spherical conformal antenna array with equal amplitude and phase, an isotropic omnidirectional radiation pattern in the upper hemisphere is generated. Feeding some adjacent elements with equal amplitude and phase can generate ultra-wide beam patterns with multiple angular pointing and multiple angular coverage ranges. The array element arrangement is designed according to the following principles: T1. Based on the size of the sphere, starting from the first array element at the zenith, considering the condition that the array element spacing d is satisfied, the number of layers that need to be designed can cover the upper hemisphere. Determine the number and angle of array element replication along the meridian of 1 / 4 of the sphere, and at the same time determine the starting unit position of each layer of array. T2. The primary principle of each layer of array is to approximate the unit spacing d after completing one circle of latitude layer. After determining the unit spacing d1 and the number of units N1 for each layer, the array of that layer starts with one unit and performs a rotational copy along the Z-axis with a rotation angle of 360° / N1 to obtain the rotational copy position of the second unit. T3. The two principles in T1 and T2 can serve as the design basis for all given frequency bands, different array element designs, and different sizes of spherical conformal arrays. The Calculated from the highest frequency point of the broadband unit, and Take 60°.

2. The array element arrangement method for a conformal array antenna according to claim 1, characterized in that: The antenna layout manifold along the 1 / 4 spherical meridian in T1 is arranged as follows: based on a single element at the zenith, it is rotated and replicated along the X-axis or Y-axis at a rotation angle of 90° / M.

3. The array element arrangement method for a conformal array antenna according to claim 1, characterized in that: The T2 further includes: the second unit should then rotate along the sphere based on the copied position, with a rotation angle of 360° / N1, and so on. The third unit of the layer completes the layout by performing the above operation based on the second unit. The above principle can complete the layout manifold of all units in the layer.

4. The array element arrangement method for a conformal array antenna according to claim 1, characterized in that: S1 further includes: for a given operating frequency band and maximum scanning angle According to phased array antenna theory, the element spacing to ensure that no grating lobes appear at the maximum scanning angle is given by the following formula: .

5. The array element arrangement method for a conformal array antenna according to claim 1, characterized in that: The antenna element is right-hand circularly polarized, with the propagation direction being the positive z-axis. The circularly polarized wave is propagated along... direction and Description of the two linear polarization components in the direction: The Where t is the angular frequency, z is the time, and z is the electromagnetic wave propagation distance. The amplitude of the electric field strength is... It is the wave vector.

6. The array element arrangement method for a conformal array antenna according to claim 5, characterized in that: Rotate the antenna element counterclockwise around the z-axis After rotation, the circularly polarized wave is used This indicates a coordinate rotation diagram. and The relationship is as follows: Circularly polarized wave of the rotated antenna element It can be represented as: If the second array element is rotated 180° and placed opposite the other two array elements, the superposition of the electric fields pointing to (0°, 0°) of the two array elements can be expressed as: .

7. The array element arrangement method for a conformal array antenna according to claim 6, characterized in that: The antenna element radiating right-hand circularly polarized waves rotates counterclockwise around the z-axis. The angle is equivalent to adding a phase shift to the antenna element feed. , Pick hour They cancel each other out, resulting in 0.

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