WO2020151074A1

WO2020151074A1 - Broadband circularly-polarized millimeter wave multi-feed multi-beam lens antenna

Info

Publication number: WO2020151074A1
Application number: PCT/CN2019/079180
Authority: WO
Inventors: 蒋之浩; 张彦; 洪伟
Original assignee: 东南大学
Priority date: 2019-01-23
Filing date: 2019-03-22
Publication date: 2020-07-30
Also published as: CN109742556A; CN109742556B

Abstract

Disclosed is a broadband circularly-polarized millimeter wave multi-feed multi-beam lens antenna. The antenna comprises one multi-port broadband circularly-polarized planar feed antenna array (1) and one planar lens (2); a plane of the multi-port broadband circularly-polarized planar feed antenna array (1) is provided parallel to the plane of the planar lens (2), and a signal of the multi-port broadband circularly-polarized planar feed antenna array (1) is output or received by means of the planar lens (2). The planar lens (2) has a plurality of phase-shifted distributed focal points which consist of completely identical anisotropic unit structures (5) in a periodic arrangement. The anisotropic unit structures (5) consist of an upper metal patch (5a), a middle metal patch (5b), and a lower metal patch (5c). The antenna can realize multi-feed multi-beam characteristics, and has wide application prospects in wireless communications and satellite communications.

Description

Broadband circular polarization millimeter wave multi-feed source multi-beam lens antenna

Technical field

The invention belongs to the field of electronic devices for wireless communication systems, and specifically relates to a broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna, which has multiple input ports, and when each input port is excited, it can produce an independent point of difference Directional circularly polarized high-gain beams, therefore, this antenna can achieve circularly polarized multi-beams in a frequency band close to 20% bandwidth to cover a certain area, and can be applied to fifth-generation mobile communications, satellite communications, and millimeter wave points For multipoint communications and other fields.

Background technique

A multi-beam antenna is an electromagnetic wave radiation device that can generate multiple independent beams, and is widely used in a variety of wireless communication systems. Among them, the passive multi-beam antenna is low-cost and light, and it is a low-cost multi-beam solution. Passive multi-beam antennas can be realized by beamforming circuit networks, reflective surfaces, and lenses. They contain multiple independent input ports. When each port is excited, a pre-designed direction is generated. High gain beam. Multiple ports of this type of multi-beam antenna correspond to multiple radiation beams respectively, so as to achieve coverage of a certain angle area. Passive multi-beam antennas based on beamforming circuit networks mostly use Butler matrix, Blass matrix, or Nolen matrix, which has a narrow bandwidth and is difficult to expand to two-dimensional beam coverage. And when the number of beams to be formed is large, the volume and complexity of the circuit will increase sharply, and will bring significant loss. The passive multi-beam antenna based on the reflecting surface needs to avoid the feed antenna group from blocking the outgoing beam generated by the reflecting surface, which increases the complexity of the design and affects the overall performance of the antenna. In addition, reflector antennas are particularly sensitive to phase errors caused by surface roughness. Therefore, a passive multi-beam antenna based on a lens, especially a flat lens, has become a solution that can provide broadband two-dimensional multi-beam coverage. Although the traditional lens-based multi-beam antenna has good performance, the lens is bulky and heavy, while the flat-lens multi-beam antenna based on the flat printed structure can basically only work in a single-line polarization, with narrow bandwidth and fluctuating beam gain It still cannot meet the needs of many applications.

The present invention provides a broadband circularly polarized millimeter wave multi-feed source multi-beam lens antenna. The structure is composed of a set of broadband circularly polarized planar feed antennas and a planar lens. The planar lens is periodically arranged by identical sub-wavelength units. This multi-feed, multi-beam lens antenna can generate stable circularly polarized multi-beams within 18% of the frequency band, each port corresponds to a beam, the -3dB coverage is ±33 degrees, and the beam gain fluctuation is less than 1.5dB. Compared with the existing multi-feed multi-beam lens antenna, the present invention has the advantages of circular polarization, wide working bandwidth, wide scanning range, small beam gain fluctuation, etc., and is important in the future fifth-generation mobile communications, satellite communications and other fields. Prospects.

Summary of the invention

Technical problem: The purpose of the present invention is to provide a broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna, which has the characteristics of broadband, circular polarization, and small gain fluctuation, and can efficiently realize broadband circularly polarized multi-beam coverage.

Technical Solution: The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna of the present invention includes a multi-port broadband circularly polarized planar feed antenna array and a planar lens; multi-port broadband circularly polarized planar feed The plane of the source antenna array is arranged parallel to the plane of the plane lens, and the signal of the multi-port broadband circularly polarized plane feed antenna array is output or received through the plane lens.

The multi-port broadband circularly polarized planar feed antenna array is composed of a plurality of broadband circularly polarized planar feed antenna units; the broadband circularly polarized planar feed antenna unit is located on the plane of the multi-port broadband circularly polarized planar feed antenna array on.

Each broadband circularly polarized planar feed antenna element is surrounded by a metal isolation through hole array.

Each broadband circularly polarized planar feed antenna unit includes an anisotropic impedance surface antenna cladding on the top layer, a plane cut corner patch antenna on the middle layer, and a substrate integrated waveguide on the bottom layer.

The plane cut-angle patch antenna and the substrate integrated waveguide are connected by a metal feeding column or a feeding slot.

The substrate integrated waveguide is connected to an external device or circuit through a coplanar waveguide structure.

The plane lens is composed of completely the same anisotropic unit structure arranged in a period, and the period is not more than 1/2 wavelength.

The anisotropic unit structure is composed of an upper layer metal patch, a middle layer metal patch and a lower layer metal patch.

The phase shift of the plane lens has multiple focal points.

The multi-port broadband circularly polarized planar feed antenna array is located at the focal plane of the planar lens.

Beneficial effects: The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna proposed by the present invention has the following advantages:

(1) Circular polarization multi-feed source and multi-beam can be realized. By adopting a circularly polarized planar feed antenna array, each feed antenna has an independent input port and radiates left-handed circularly polarized waves. In addition, the anisotropic unit structure of the lens is designed to make the left-hand circular The polarized incident wave is converted into a right-handed circularly polarized transmitted wave, and it carries a phase delay proportional to the horizontal rotation angle of the basic unit structure, and then converts the wide-beam left-handed circularly polarized wave emitted by the feed antenna into a high The gain is right-handed circularly polarized directional beam, and the beams corresponding to different input ports point to different directions, and the mutual interference is very low.

(2) It has broadband characteristics. This is due to the adoption of a broadband planar feed antenna, which uses an anisotropic impedance surface antenna cladding and a planar cut-angle patch antenna, which is a laminated double resonant structure, which can greatly broaden the impedance bandwidth and axial ratio bandwidth of the planar feed antenna. At the same time, the transmission phase of the circularly polarized wave produced by the anisotropic unit structure of the plane lens is completely controlled by the geometric phase generated by the rotating anisotropic unit structure, so the phase shift does not change with the change of frequency, so it is necessary to expand the axial ratio bandwidth It helps a lot.

(3) It has the characteristics of high beam gain flatness. By adjusting the electromagnetic response of the anisotropic unit structure of the plane lens with frequency, the fluctuation of the antenna gain with the frequency can be reduced. In addition, by using a flat lens with a multi-focus phase distribution, the gain difference between the edge beam and the center beam can be reduced. The simultaneous application of these two technologies can significantly improve the flatness of the beam gain in the frequency domain and the angular domain.

(5) It has the characteristics of lightness, high integration and low cost. This is because both the planar lens and the planar feed antenna use a medium substrate with sub-wavelength thickness, which can be fabricated by traditional printed circuit board technology, and is easy to integrate, so that the total cross-section of the multi-beam antenna is less than 3 wavelengths.

Description of the drawings

Figure 1 shows a three-dimensional schematic diagram of the multi-feed multi-beam lens antenna of the present invention.

Figure 2 is a top view of the top metal structure of the broadband circularly polarized planar feed antenna unit,

Figure 3 is a top view of the middle metal structure of the broadband circularly polarized planar feed antenna unit,

Figure 4 is a top view of the underlying metal structure of the broadband circularly polarized planar feed antenna unit,

Fig. 5 is a three-dimensional schematic diagram of the anisotropic unit structure of a plane lens,

In the figure, there are: multi-port broadband circularly polarized planar feed antenna array 1, planar lens 2, broadband circularly polarized planar feed antenna unit 3, anisotropic impedance surface antenna coating 3a, planar cut-off patch antenna 3b, Substrate integrated waveguide 3c, metal feed pillar 3d, coplanar waveguide structure 3e, metal isolation through hole array 4, anisotropic unit structure 5, upper metal patch 4a, middle metal patch 4b, and lower metal patch 4c.

Figure 6 shows the measured reflection coefficient versus frequency curve of the five input ports of the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna;

Figure 7 shows the measured port mutual coupling between different input ports of the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna with frequency;

Figure 8 shows the measured left-hand circular polarization and right-hand circular polarization normalized pattern when the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna excites five input ports respectively, (a) 24GHz, ( b) 26GHz, (c) 28GHz;

Figure 9 shows the simulated and measured gain versus frequency curves when the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna excites five input ports respectively.

detailed description

The multi-port broadband circularly polarized planar feed antenna array is located near the focal plane of the planar lens, and the vertical distance between the planar feed antenna array and the planar lens is F, and the diameter of the planar lens is D, where 0.3≤F/D≤ 0.6.

The multi-port broadband circularly polarized planar feed antenna array is composed of a plurality of broadband circularly polarized planar feed antenna units, and each broadband circularly polarized planar feed antenna unit is surrounded by an array of metal isolation through holes.

The broadband circularly polarized planar feed antenna unit includes an anisotropic impedance surface antenna cladding layer on the top layer, a plane cut corner patch antenna on the middle layer, and a substrate integrated waveguide on the bottom layer.

The plane cut-angle patch antenna located in the middle layer of the feed antenna unit is connected to the substrate integrated waveguide by a metal feed column or feed slot, and the substrate integrated waveguide is connected to an external device or circuit through a coplanar waveguide structure.

The plane lens is composed of identical anisotropic unit structures arranged in cycles, and the unit period is not greater than 1/2 wavelength.

The structure and size of the upper metal patch and the lower metal patch of the anisotropic unit structure of the plane planar lens are completely the same, and are composed of an elliptical patch with an I-shaped groove in the middle.

The middle metal patch of the anisotropic unit structure of the plane lens includes an elliptical patch with an "I"-shaped groove in the middle.

The upper metal patch, middle metal patch, and lower metal patch of the basic unit structure of the flat lens have the same horizontal rotation angle.

The thickness of the first layer of dielectric substrate and the second layer of dielectric substrate of the plane lens are the same and less than 1/3 of the wavelength.

The horizontal rotation angles of all the units of the plane lens are in a certain distribution, and the phase distribution has two or more focal points.

The present invention will be further described below in conjunction with the drawings.

The broadband circularly polarized millimeter wave multi-feed source and multi-beam lens antenna of the present invention adopts a circularly polarized planar antenna array as the feed source of the planar lens. Each feed antenna radiates left-handed circularly polarized waves and has its own independent input port. The feed antenna includes an anisotropic impedance surface antenna cladding on the top layer, a plane cut-angle patch antenna on the middle layer, and a substrate integrated waveguide on the bottom layer. The plane cut-angle patch antenna and the substrate integrated waveguide consist of one The metal feed posts are connected, and the substrate integrated waveguide is connected to an external device or circuit through a coplanar waveguide structure. The anisotropic impedance surface antenna coating on the top layer of the feed antenna is composed of N (2≤N≤6) separate patches. The side length of each patch is in the range of 0.2～0.4 wavelength. The shift is 180°/N. Therefore, when N patches are capacitively coupled, two orthogonal standing wave resonance modes similar to traditional patch antennas can be generated in the required frequency band, thereby achieving circular polarization radiation. At the same time, the plane cut-angle patch antenna located in the middle layer of the feed antenna can also provide narrowband circularly polarized radiation. The combined use of these two narrowband circularly polarized structures can greatly broaden the impedance bandwidth and axial ratio bandwidth of the planar feed antenna. The gain of the feed antenna unit is about 9dBic. In addition, by adding a metal isolation through hole array around the planar feed antenna unit, the mutual coupling between the units caused by surface waves can be effectively suppressed, and the isolation between the multiple input ports of the multi-beam antenna can be improved.

For the flat lens design, by designing the anisotropic unit structure of the flat lens, it converts the left-handed circularly polarized incident wave into the right-handed circularly polarized transmitted wave, and then carries a horizontal rotation angle proportional to the basic unit structure The phase delay then converts the wide-beam left-handed circularly polarized wave emitted by the planar feed antenna into a high-gain right-handed circularly polarized directional beam, and the beams corresponding to different input ports point to different directions, and the mutual interference is very low. The center of the feed antenna array is on the same line as the center axis of the plane lens, the distance between the two is F, the diameter of the plane lens is D, and the value of F/D should be between 0.3 and 0.6. 0.38. The plane lens is composed of completely the same anisotropic unit structure arranged in a periodic combination, the period is 1/3 wavelength, and each unit rotates a certain angle around the central axis of the unit on the horizontal plane. The anisotropic unit structure of the plane lens is composed of three metal layers. Between the three metal layers are two dielectric substrates with the same thickness. The thickness of each dielectric substrate is controlled at 1/6 wavelength. Among them, the structure and size of the upper metal patch and the lower metal patch are exactly the same, and the three-layer metal patch is composed of an oval patch with an "I"-shaped slot in the middle. By optimizing the size of the three-layer metal patch of the anisotropic unit structure of the lens and the thickness of the dielectric substrate, impedance matching can be achieved with the free space, ensuring a high transmission amplitude. What is important is that since the basic unit of the transmission array is smaller than the wavelength and thinner, its electromagnetic response is basically the same within the range of 0-40° incident angle. In addition, by optimizing the frequency response of the anisotropic unit structure of the plane lens, the left-handed incident wave can be converted into a right-handed transmission wave within a bandwidth of about 20%, and accompanied by a transmission that is completely determined by the horizontal rotation angle of the basic unit structure The phase shift, and the transmission amplitude is higher than 70%.

Combining this broadband planar circularly polarized feed antenna with a broadband planar lens can obtain a broadband circularly polarized high gain beam. In addition, by optimizing the horizontal rotation angle distribution of all units in the plane lens to have two focal points, the gain difference between the edge beam and the center beam can be reduced. The simultaneous application of the multifocal lens phase distribution and broadband feed antenna/broadband lens technologies can significantly improve the flatness of the beam gain in the frequency domain and the angular domain.

Figure 1 shows a three-dimensional schematic diagram of the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna. Figures 2, 3, and 4 show the top layer, The metal structure of the middle and bottom layers is intended. Figure 5 shows a three-dimensional schematic diagram of the anisotropic unit structure of the flat lens.

Fig. 6 shows the curve of the measured reflection coefficient of the five input ports of the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna with frequency. It can be seen that the reflection coefficient of the five ports is less than -12dB in the range of 24-29GHz, and even less than -15dB at most frequencies, indicating that the impedance matching of each port is very good.

Figure 7 shows the measured port mutual coupling between different input ports of the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna with frequency. It can be seen that the mutual coupling between adjacent ports is less than -20dB in the 24-29GHz range, and the mutual coupling between non-adjacent units is less than -23dB in the 24-29GHz range, indicating the isolation between different ports well.

Fig. 8 shows the measured 24 GHz, 26 GHz, and 28 GHz left-hand circular polarization and right-hand circular polarization normalized patterns when the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna excites five input ports respectively. It can be seen that the five ports correspond to five highly directional right-handed circularly polarized beams, and each beam points in a different direction. The beam direction and shape remain stable throughout the frequency band, and the -3dB coverage range is ±33 degrees; in addition, , The gain of the right-handed circularly polarized wave is very low, indicating that the cross polarization is very good.

Figure 9 shows the simulated and measured gain versus frequency curves when the broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna excites five input ports respectively. It can be seen that the simulation and actual measurement results are in good agreement. The axial ratio of each beam is less than 3dB within 24-29GHz, and their gain varies with frequency less than 2dB. Importantly, due to the use of a bifocal flat lens, the edge The difference between the gain of the beam and the gain of the center beam is less than 1.5dB, indicating that the beam gain of the multi-beam antenna is very flat in the frequency domain and the angular domain.

The invention provides a broadband circularly polarized millimeter wave multi-feed source multi-beam lens antenna. The antenna includes a multi-port broadband circularly polarized planar feed antenna array 1 and a planar lens 2. The multi-port broadband circularly polarized planar feed antenna array 1 is located near the focal plane of the planar lens 2. The multi-port broadband circularly polarized planar feed antenna array 1 is composed of a plurality of broadband circularly polarized planar feed antenna units 3. The broadband circularly polarized planar feed antenna unit 3 is surrounded by a metal isolation through hole array 4, each A broadband circularly polarized planar feed antenna unit 3 includes an anisotropic impedance surface antenna cladding layer 3a on the top layer, a plane cut corner patch antenna 3b on the middle layer, and a substrate integrated waveguide 3c on the bottom layer. The planar corner-cut patch antenna 3b and the substrate integrated waveguide 3c are connected by a metal feeder 3d, and the substrate integrated waveguide 3c is connected with an external device through a coplanar waveguide structure 3e. The plane lens 2 has a plurality of focal points distributed in phase shift, and is composed of exactly the same anisotropic unit structure 5 arranged in cycles. The anisotropic unit structure 5 is composed of an upper metal patch 5a, a middle metal patch 5b and a lower metal patch 5c.

In summary, the present invention provides a broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna with circular polarization, wide working bandwidth, high port isolation, wide beam coverage, low cross-polarization, and beam gain The advantages of small fluctuations have important prospects in the future 5th generation mobile communications, satellite communications and other fields.

The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

A broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna, characterized in that the antenna includes a multi-port broadband circularly polarized planar feed antenna array (1) and a plane lens (2); The plane of the polarized plane feed antenna array (1) is arranged in parallel with the plane of the plane lens (2), and the signal of the multi-port broadband circularly polarized plane feed antenna array (1) is output or received through the plane lens (2).
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, wherein the multi-port broadband circularly polarized planar feed antenna array (1) is composed of multiple broadband circularly polarized planar feeds The antenna unit (3) is composed; the broadband circularly polarized planar feed antenna unit (3) is located on the plane of the multi-port broadband circularly polarized planar feed antenna array (1).
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 2, wherein each broadband circularly polarized planar feed antenna unit (3) is surrounded by a metal isolation through-hole array (4).
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, wherein each broadband circularly polarized planar feed antenna unit (3) includes an anisotropic impedance surface antenna cover on the top layer Layer (3a), a plane cut-angle patch antenna (3b) located in the middle layer and a substrate integrated waveguide (3c) located in the bottom layer.
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, characterized in that the plane cut-angle patch antenna (3b) and the substrate integrated waveguide (3c) are formed by a metal feed column (3d) Connected, or connected by a feed slot.
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, wherein the substrate integrated waveguide (3c) is connected to an external device or circuit through a coplanar waveguide structure (3e).
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, wherein the planar lens (2) is composed of exactly the same anisotropic unit structure (5) arranged in cycles, and the period is not Greater than 1/2 wavelength.
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, wherein the anisotropic unit structure (5) consists of an upper metal patch (5a) and a middle metal patch (5b) And the lower metal patch (5c).
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 7, wherein the phase shift of the plane lens (2) is distributed with multiple focal points.
The broadband circularly polarized millimeter wave multi-feed multi-beam lens antenna according to claim 1, wherein the multi-port broadband circularly polarized planar feed antenna array (1) is located at the focal plane of the planar lens (2) .