Magnetoelectric dipole array

Abstract

The invention discloses a magnetoelectric dipole array, and solves the problems that in the prior art, the height is large, conformal design of an antenna and a platform is inconvenient, and cross polarization is poor. Wherein the magnetoelectric dipole comprises a feed balun, a half-wave vibrator and a vibrator arm. The half-wave oscillator is a horizontally-arranged metal patch and is connected with a floor through an oscillator arm to form an annular current path. The feed balun is used for exciting the magnetoelectric dipole and comprises a horizontal part, a first vertical part and a second vertical part. The horizontal part and the metal patch are in the same plane, and a first vertical part and a second vertical part are arranged on the sides, right facing the floor, of the two ends of the horizontal part respectively. The first vertical part is connected with a feed port on the floor, and the second vertical part is not in contact with the floor. According to the invention, the magnetoelectric dipole array elements are applied to the planar tight coupling array, so that the low profile and polarization isolation of the antenna are ensured.

Description

Technical Field

[0001] This application relates to the field of electronic science and technology, and particularly to a magnetoelectric dipole array. Background Art

[0002] Phased array antennas have advantages such as fast beam scanning, integrated beamforming, and adaptive anti-jamming capabilities, and are widely used in airborne radars. With the enrichment of the application scenarios of airborne radars, higher requirements are put forward for the multi-band, multi-functional, and miniaturization of antenna systems. Therefore, the problems of insufficient matching bandwidth, limited scanning range, and large profile height of array antennas are becoming increasingly prominent. In addition, reducing the antenna height can prevent the antenna from having an adverse impact on the aerodynamics and radar cross-section of the platform, which is an important factor to be considered in the design process.

[0003] In traditional wideband wide-scan arrays, Vivaldi antennas and end-fire dipoles are vertical structures and usually have a large height, which makes the conformal design of the antenna with the platform more difficult. In a dual-polarized electric dipole array, in order to increase the coupling capacitance between array elements to cancel the inductive component in the input impedance at low frequencies, adjacent array elements need to be tightly coupled together. Such a structure also increases the mutual coupling between horizontal polarization and vertical polarization, resulting in the deterioration of the cross-polarization index of the array. At the same time, the operating bandwidth of traditional magnetoelectric dipoles is not sufficient to cover both the X and Ku bands simultaneously. Summary of the Invention

[0004] The embodiments of this application provide a magnetoelectric dipole array, which solves the problems of large height in the prior art, inconvenience in the conformal design of the antenna with the platform, and poor cross-polarization.

[0005] The embodiments of this application provide a magnetoelectric dipole array, in which the magnetoelectric dipole includes a feeding balun, a half-wave dipole, and a dipole arm. The half-wave dipole is a horizontally arranged metal patch, and forms a circular current path by connecting to the ground plane through the dipole arm. The feeding balun is used to excite the magnetoelectric dipole and includes a horizontal part, a first vertical part, and a second vertical part. The horizontal part is in the same plane as the metal patch, and the first vertical part and the second vertical part are respectively arranged at both ends facing the ground plane. The first vertical part is connected to the feeding port on the ground plane, and the second vertical part does not contact the ground plane.

[0006] Further, one of the half-wave dipoles is connected to three dipole arms.

[0007] In one of the embodiments, half-wave dipoles are respectively arranged at both ends of the feeding balun along the length direction of the horizontal part.

[0008] Preferably, the magnetoelectric dipole array of the embodiment of the present application includes a wide-angle impedance matching layer, a radiation element layer, and a metal ground. The radiation element layer includes an array composed of the magnetoelectric dipoles in any one of the embodiments. The metal ground is disposed on the lower surface of the radiation element layer.

[0009] In one embodiment, the magnetic dipoles of H polarization and V polarization in the array are orthogonally arranged at a set periodic distance.

[0010] In one embodiment, the arms of adjacent dipoles are mutually coupled through a slot capacitance.

[0011] In one embodiment, the radiation element layer includes two overlapping and bonded dielectric plates, and the horizontal part of the feeding balun is disposed on the upper surface of the upper dielectric plate. The first vertical part enters the radiation element layer from the bottom surface of the lower dielectric plate through a through hole. The second vertical part extends downward from the horizontal part through a blind hole to between the two dielectric plates.

[0012] In one embodiment, the magnetic dipoles of H polarization and V polarization included in the array are of a set number. The edge of the array is loaded with short-circuited virtual array elements.

[0013] In one embodiment, the wide-angle impedance matching layer is a WAIM layer. The WAIM layer is composed of metal patches arranged periodically in the E plane and the H plane.

[0014] In one embodiment, through holes are periodically provided in the metal ground and the wide-angle impedance matching layer. The through holes are aligned with the holes in the ring structure formed by the H-polarized and V-polarized magnetic dipoles on the same horizontal plane.

[0015] The above technical solutions comprehensively adopted in the embodiments of the present application can achieve the following beneficial effects: The present application applies magnetoelectric dipole array elements to a planar tightly coupled array. While ensuring the low profile of the antenna, it realizes a wide-angle scan of ±60° for both H / V polarizations in the X and Ku dual frequency bands of the array. At the same time, by using the superposition of electric dipole sources and magnetic dipole sources, ultra-low cross polarization is achieved. Description of the Drawings

[0016] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation to the present application. In the drawings: Figure 1 Schematic diagram of a prior art vivaldi antenna; Figure 2 Schematic diagram of a prior art end-fire dipole array; Figure 3-1Schematic top view of the prior art PUMA array; Figure 3-2 Schematic horizontal cross-section of the prior art PUMA array; Figure 4 Structural diagram of a magnetoelectric dipole provided by an embodiment of the present application; Figure 5 Structural diagram of a dual-band dual-polarization tightly coupled magnetoelectric dipole array provided by an embodiment of the present application; Figure 6 Schematic diagram of the arrangement of the magnetoelectric dipole array provided by an embodiment of the present application; Figure 7 Schematic diagram of a finite-size array provided by an embodiment of the present application; Figure 8 Schematic diagram of the WAIM layer based on a high-impedance surface provided by an embodiment of the present application; Figure 9-1 Schematic diagram of the active standing wave ratio when the beam is directed normal provided by an embodiment of the present application; Figure 9-2 Schematic diagram of the active standing wave ratio when the beam is scanned in the D plane provided by an embodiment of the present application; Figure 9-3 Schematic diagram of the active standing wave ratio when the beam is scanned in the E plane provided by an embodiment of the present application; Figure 9-4 Schematic diagram of the active standing wave ratio when the beam is scanned in the H plane provided by an embodiment of the present application; Figure 10-1 8 GHz, H-plane radiation pattern of the 5×5 array provided by an embodiment of the present application; Figure 10-2 8 GHz, E-plane radiation pattern of the 5×5 array provided by an embodiment of the present application; Figure 10-3 13 GHz, H-plane radiation pattern of the 5×5 array provided by an embodiment of the present application; Figure 10-4 13 GHz, E-plane radiation pattern of the 5×5 array provided by an embodiment of the present application; Figure 10-5 18 GHz, H-plane radiation pattern of the 5×5 array provided by an embodiment of the present application; Figure 10-6 18 GHz, E-plane radiation pattern of the 5×5 array provided by an embodiment of the present application. Detailed implementation manners

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments of this application and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts belong to the scope of protection of this application.

[0018] Currently, the most common wideband scanning array is the Vivaldi antenna and its variants. As an exponentially tapered non-resonant traveling-wave antenna, the Vivaldi antenna has characteristics such as a wide operating frequency band, high gain, and simple structure. As Figure 1 shown in the all-metal Vivaldi antenna, after forming an 8×8 dual-polarized array, it can achieve a 30° beam scan in the frequency range of 2 - 18 GHz.

[0019] Another approach to ultra-wideband (UWB) array design is to design a tightly-coupled dipole array (TCDA), which originated from the concept of the infinite current sheet array (CSA) proposed by Wheeler. Based on the CSA theory, by introducing capacitive coupling between the dipoles to cancel the influence of the inductance introduced by the metal ground, such an array can achieve a working bandwidth of more than 4:1.

[0020] TCDA arrays can be roughly divided into two types: end-fire dipole arrays and planar dipole arrays. By interconnecting a balun with vertically mounted end-fire dipoles, balanced feeding of the two arms of the dipole can be achieved, thus ensuring the radiation performance of the antenna array. As Figure 2 shown, the antenna unit can achieve a ±45° one-dimensional scan after arraying, with an octave bandwidth of 7.35:1. The end-fire dipole array realizes balanced feeding through a balun and can achieve a ±45° one-dimensional scan within an octave bandwidth of 7.35:1. This design broadens the working bandwidth through capacitive coupling.

[0021] In addition to the end-fire dipole array, a modular planar ultra-wideband antenna (PUMA) array can achieve a more compact topology. As shown, the dual-polarized PUMA array has a working bandwidth of 3:1 and a scanning angle of up to ±45°. As Figure 3-1 shown Figure 3-2As shown, the array consists of three dielectric plates. The H- and V-polarized dipoles are printed on the top and bottom of the substrate 2 (the middle layer), respectively. The metallized vias for implementing the feeder line and shorting posts pass through the substrate 3 (the bottom layer) and are connected to the two arms of the dipole. The substrate 1 is placed above the radiating element to improve the impedance matching performance of the array and expand the scanning range of the antenna. The dual-polarized PUMA array consists of three dielectric plates. The H-polarized and V-polarized dipoles are printed on the top and bottom of the middle layer, respectively, and are connected to the feeder line through metallized vias. The array can achieve a scan of ±45° within a 3:1 operating bandwidth.

[0022] The following will, in conjunction with the accompanying drawings, detail the technical solutions provided by the embodiments of the present application.

[0023] Figure 4 A magnetoelectric dipole structure diagram provided by an embodiment of the present application includes a feeding balun 410 ( Figure 5 marked), a half-wave dipole 420, and a dipole arm 430.

[0024] The half-wave dipole is a horizontally arranged metal patch, and forms a circular current path by connecting to the ground plane through the dipole arm.

[0025] The feeding balun is used to excite the magnetoelectric dipole and includes a horizontal part 410-2, a first vertical part 410-1, and a second vertical part 410-3.

[0026] The horizontal part is in the same plane as the metal patch, and the first vertical part and the second vertical part are respectively arranged at both ends facing the ground plane side. The first vertical part is connected to the feeding port on the ground plane, and the second vertical part does not contact the ground plane.

[0027] Further, one half-wave dipole is connected to three dipole arms.

[0028] In one embodiment, half-wave dipoles are respectively arranged at both ends of the feeding balun along the length direction of the horizontal part.

[0029] For example, the horizontally placed metal patch forms a traditional half-wave dipole. The three grounding vias connected to the dipole arm and the ground plane form a circular current path, forming an equivalent magnetic fluid. The feeding balun composed of a microstrip line, a via, and a blind via is used to excite the magnetoelectric dipole, and the feeding port on the ground plane can be directly interconnected with an SSMP.

[0030] For another example, Figure 4 in which r1 = 0.4 mm, r2 = 0.6 mm, r3 = 0.2 mm, r4 = 0.2 mm, h1 = 5.25 mm, and h2 = 1.524 mm.

[0031] Figure 5A structural diagram of a dual-band and dual-polarized tightly coupled magnetoelectric dipole array provided by an embodiment of the present application, including a wide-angle impedance matching layer 510, a radiation element layer 520, and a metal ground (not shown in the figure).

[0032] The radiation element layer includes an array composed of magnetoelectric dipoles according to any one of the embodiments of the first aspect. The metal ground is disposed on the lower surface of the radiation element layer.

[0033] In one embodiment, the radiation element layer includes two overlapping and bonded dielectric plates, and the horizontal portion of the feeding balun is disposed on the upper surface of the upper dielectric plate 520-1. The first vertical portion enters the radiation element layer from the ground of the lower dielectric plate 520-2 through a via hole. The second vertical portion extends downward from the horizontal portion through a blind hole to between the two dielectric plates.

[0034] For example, the dual-polarized magnetoelectric dipole array is composed of a radiation element 520 and a wide-angle impedance matching (WAIM) layer 510, and altogether includes three layers of RO6002 dielectric plates, with a relative permittivity ε r = 2.92. The three layers of PCBs are bonded by prepregs. Each layer of the board has a thickness of 1.524 mm, and each layer of the prepreg has a thickness of 0.202 mm. The total height of the antenna is about 0.1327*λ L， λ L is the wavelength of electromagnetic waves in free space at the lowest frequency (8 GHz). As Figure 5 shown, from top to bottom, the first layer of PCB is a wide-angle matching layer based on the nature of the high-impedance surface; the second and third layers are the oscillators, oscillator arms, and feeding baluns of the magnetoelectric dipoles, and the feeding balun is composed of short-circuit vias, feeding through holes (i.e., the first vertical portion), horizontal microstrip lines (i.e., the horizontal portion), and blind holes (i.e., the second vertical portion).

[0035] In one embodiment, the magnetic dipoles of H polarization and V polarization in the array are orthogonally arranged at a set periodic distance.

[0036] In one embodiment, the arms of adjacent dipoles are mutually coupled through gap capacitors.

[0037] In order to further broaden the matching bandwidth of the magnetoelectric dipole, a tightly coupled system is adopted in the array design.

[0038] As Figure 4 and Figure 5 shown, the magnetoelectric dipole array is composed of half-wave oscillators, oscillator arms, and feeding baluns. Through the tight coupling design, the arms of adjacent dipoles are mutually coupled through gap capacitors, further broadening the operating bandwidth. As Figure 6 shown, the magnetic dipoles of two polarizations (H polarization and V polarization) have a periodic pitch P = λH / 2 orthogonal arrangement, λ H is the wavelength of electromagnetic waves in free space at the highest frequency (18 GHz). The arms of adjacent dipoles are mutually coupled through slot capacitors to cancel out the inductive component introduced by the metal ground plane in the input impedance at low frequencies.

[0039] In the array, an equivalent resonant cavity will be formed around the arranged metallized vias and the metal ground. At resonance, it will cause scanning blind spots in the antenna. In order to reduce the equivalent dielectric constant in the cavity and shift the resonant frequency outside the operating frequency band, holes need to be periodically drilled in the metal ground and the dielectric substrate (i.e., the wide-angle impedance matching layer), and the radius of the hole is R0 = 2.7 mm.

[0040] For another example, Figure 6 in it, l1 = 4.6 mm, l2 = 2 mm, l3 = 2.2 mm, ls = 0.2 mm.

[0041] Such as Figure 6 shown, the magnetic dipoles of H polarization and V polarization are orthogonally arranged at a periodic distance, and can achieve a low standing wave ratio and wide-angle scanning in the frequency range of 8 - 18 GHz.

[0042] In one of the embodiments, the number of magnetic dipoles of H polarization and V polarization included in the array is set. The edge of the array is loaded with short-circuited virtual array elements.

[0043] In practical applications, the antenna array will not be infinite. In an array with a finite size, the reflection of electromagnetic waves at the edge of the array will cause a truncation effect, deteriorating the antenna standing wave and radiation pattern. As Figure 7 shown, one is an array composed of 5 × 5 array elements. In this design, short-circuited virtual array elements are loaded around the finite-sized array, which can effectively eliminate the truncation effect.

[0044] In one of the embodiments, the wide-angle impedance matching layer is a WAIM layer. The WAIM layer is composed of metal patches periodically arranged in the E-plane and H-plane.

[0045] In one of the embodiments, the metal ground and the wide-angle impedance matching layer are periodically provided with through holes. The through holes are opposite to the holes in the ring structure surrounded by the magnetic dipoles of H polarization and V polarization on the same horizontal plane.

[0046] The active impedance of the array antenna varies with the scanning angle θ, that is, it is multiplied by cosθ in the E-plane and multiplied by 1 / cosθ in the H-plane. This impedance variation leads to input impedance mismatch of the beam during large-angle scanning. To alleviate this phenomenon, a dielectric substrate is usually placed above the antenna aperture, and the refraction of electromagnetic waves by the dielectric reduces the impedance variation with the scanning angle. However, the surface of a planar conductor with a thin dielectric layer supports the propagation of surface waves, which causes energy to be coupled back to the antenna port instead of radiating forward, thus creating blind spots during large-angle scanning. Therefore, the dielectric layer used for wide-angle matching of the array is usually very thick. To overcome the scanning blind spots caused by surface waves and reduce the height of the antenna aperture, this application adopts a wide-angle impedance matching layer (WAIM layer) based on a high-impedance surface. Figure 8 FIG. is a schematic diagram of the WAIM layer provided by an embodiment of this application. It consists of metal patches periodically arranged in the E-plane and H-plane. The distributed capacitance and inductance of the periodic structure confine the electromagnetic field to form a high-impedance surface, thereby suppressing surface waves.

[0047] For another example, as Figure 8 shown, d1 = 2mm, ds = 0.2mm.

[0048] Compared with the traditional magnetoelectric dipole array, this design introduces magnetoelectric dipole units into the tightly coupled array and uses planar slots to introduce capacitive mutual coupling between array elements, broadening the operating bandwidth of the magnetoelectric dipole array. As Figures 9-1 to 9-4 shown, when the beam points to the normal direction, in the range of 8 - 18 GHz, the active voltage standing wave ratio of the tightly coupled magnetoelectric dipole array is less than 1.92. The maximum active voltage standing wave ratio appears when the beam scans 60° in the E-plane of the beam. At this time, in the range of 8 - 18 GHz, the maximum active voltage standing wave ratio is 3.67. There are no scanning blind spots within the entire operating frequency band.

[0049] Utilizing the principle of complementary patterns of magnetic dipoles and electric dipoles, the defect of deteriorated cross polarization of the tightly coupled array is overcome. Figures 10-1 to 10-5 FIG. shows the patterns of a 5×5 array at 8 GHz, 13 GHz, and 17 GHz. The cross-polarization isolation degrees in the direction of 0° are all greater than 35 dB, which are 44 dB, 56 dB, and 36 dB respectively.

[0050] The above are only the embodiments of this application and are not used to limit this application. For those skilled in the art, various changes and modifications can be made to this application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the scope of the claims of this application.

Claims

1. A magnetoelectric dipole array, characterized in that, The magnetoelectric dipole therein includes a feeding balun, a half-wave dipole and dipole arms; The half-wave dipole is a horizontally arranged metal patch, and forms a loop current path by connecting to the ground plane through the dipole arms; The feeding balun is used to excite the magnetoelectric dipole and includes a horizontal portion, a first vertical portion and a second vertical portion; The horizontal portion is in the same plane as the metal patch, and the first vertical portion and the second vertical portion are respectively arranged at both ends facing the ground plane side; The first vertical portion is connected to the feeding port on the ground plane, and the second vertical portion does not contact the ground plane.

2. The magnetoelectric dipole array according to claim 1, characterized in that One half-wave dipole is connected to three dipole arms.

3. The magnetoelectric dipole array according to claim 1, wherein Half-wave dipoles are respectively arranged at both ends of the feeding balun along the length direction of the horizontal portion.

4. The magnetoelectric dipole array according to any one of claims 1 to 3, characterized in that, It includes a wide-angle impedance matching layer, a radiation element layer and a metal ground; The radiation element layer includes an array composed of the magnetoelectric dipoles; The metal ground is arranged on the lower surface of the radiation element layer.

5. The magnetoelectric dipole array according to claim 4, wherein, In the array, the magnetic dipoles of H polarization and V polarization are orthogonally arranged at a set periodic distance.

6. The magnetoelectric dipole array according to claim 4, wherein The arms of adjacent dipoles are mutually coupled through gap capacitors.

7. The electric dipole array according to claim 4, wherein The radiation element layer includes two overlapping and bonded dielectric plates, and the horizontal portion of the feeding balun is arranged on the upper surface of the upper dielectric plate; The first vertical portion enters the radiation element layer from the bottom surface of the lower dielectric plate through a through hole; The second vertical portion extends downward from the horizontal portion through a blind hole to between the two dielectric plates.

8. The magnetoelectric dipole array according to claim 4, wherein The number of magnetic dipoles of H polarization and V polarization included in the array is a set number; Virtual elements with short circuits are loaded at the edge of the array.

9. The magnetoelectric dipole array according to claim 4, wherein The wide-angle impedance matching layer is a WAIM layer; The WAIM layer is composed of metal patches periodically arranged in the E plane and the H plane.

10. The magnetoelectric dipole array according to claim 4, characterized in that, Non-metal through holes are periodically arranged in the metal ground and the wide-angle impedance matching layer; The through holes are opposite to the holes in the ring structure surrounded by the magnetic dipoles of H polarization and V polarization in the same horizontal plane.

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