CN105789908A - Novel cylindrical surface luneberg lens antenna capable of realizing circular polarization or bi-circular polarization - Google Patents

Abstract

The invention discloses a novel circular polarization or double circular polarization cylindrical luneberg lens antenna. The main structure of the present invention comprises a linearly polarized feed antenna 1 attached to the peripheral surface of the cylindrical lens and the polarization direction is at an angle of 45° to the axial direction of the lens (when realizing double circular polarization, it should be replaced with a double linear pole feed) and a dielectric plate waveguide lens 2 with a certain rotationally symmetrical cross-sectional shape to meet the required refractive index and produce a 90° phase difference between the horizontally polarized TE0 wave and the vertically polarized TM0 wave. The present invention has the structural feature of rotational symmetry, so the present invention can also be applied to the usage scenario of multi-beam scanning in azimuth plane. At this time, it is only necessary to arrange the arc-shaped feed array along the circumference of the cylindrical dielectric plate waveguide lens, and adjust the spacing between the arc-shaped feed array elements according to the beam width generated by a single feed, so as to realize uninterrupted beam scanning in the azimuth plane. The invention has simple structure, mature and stable processing technology, and is especially suitable for the millimeter wave frequency band. Based on the basic structure of the present invention, other specific implementations of the present invention can be formed by rationally changing the type of the linearly polarized feed source, the shape of the lens section and the size of the antenna.

Description

A New Cylindrical Lunberg Lens Antenna with Circular Polarization or Dual Circular Polarization

technical field

The invention belongs to the technical field of antennas, and relates to a cylindrical Lunberg lens antenna, specifically a cylindrical Lunberg lens antenna based on a dielectric plate waveguide that can realize circular polarization or double circular polarization, and is suitable for millimeter wave frequency bands Scenarios for multi-beam directional communication and beam scanning.

Background technique

With the prosperity of the mobile Internet industry, the rise of the concept of the Internet of Things, and the rapid development of technologies such as satellite communication technology, navigation technology, and radar anti-interference, from the analysis of spectrum resources, the traditional low-frequency spectrum resources have been exhausted and cannot meet the needs of communication capacity. needs, it is necessary to expand high-band applications. At the same time, compared with the linearly polarized antenna, the circularly polarized antenna can receive linearly polarized waves in any polarization direction, and when used as a transmitting antenna, the circularly polarized waves radiated by the circularly polarized antenna can be detected by the linearly polarized waves Polarized antennas are accepted. Circularly polarized waves can also reduce the influence of multipath effects between the transmitting and receiving antennas, and suppress the depolarization effect caused by the natural environment during long-distance transmission. Therefore, the circularly polarized antenna can better ensure the smooth communication link. In addition, today's various applications put forward more stringent requirements for antennas: the communication of large-capacity satellites and ground stations requires wider frequency bands and even circular polarization and dual circular polarization; multi-target tracking requires antennas with higher Gain, larger range of beam consistency and faster tracking speed; in addition, in some occasions that require multiple beams, such as microwave remote sensing and automotive anti-collision radar, low-cost and efficient multi-beam communication antennas are required. Based on the above-mentioned requirements, the present invention designs a cylindrical Lunberg lens antenna based on a dielectric plate waveguide that can realize circular polarization and dual circular polarization, and is especially suitable for multi-beam directional communication and beam scanning in the millimeter wave frequency band. scenes to be used.

The concept of Lunberg lens antenna was first proposed in the 1940s. Its basic theory is to ensure that the dielectric constant of the lens medium from the inside to the outside satisfies the law of change from 2 to 1. The wave turns into a plane wave. At the same time, the cylindrical Lunberg lens antenna is a lens antenna with a rotationally symmetrical structure, and each point on the circumferential surface of the lens can be regarded as a focal point. As long as multiple feed sources are placed on the lens surface, multi-beam coverage in a wide angle range can be achieved with good beam consistency. Therefore, there is an extremely wide application market for circular polarization and dual circular polarization in the form of a cylindrical Lunberg lens antenna.

Based on the advantages of the above-mentioned cylindrical Lunberg lens antenna, professional researchers have carried out extensive research on it, and developed various forms of cylindrical Lunberg lens antenna. Patent CN102176538 proposes a multi-beam dielectric column antenna to realize multi-beam in azimuth plane, its main structure includes dielectric column lens, parallel metal plate waveguide structure and feed antenna; patent CN101587990 proposes a column antenna based on artificial metamaterials Shaped lens antenna, the antenna uses artificial metamaterials to simulate the refractive index of the standard Lunberg lens for electromagnetic waves; patent CN102122762 designs a millimeter-wave 360° omnidirectional scanning dielectric cylindrical lens antenna, the antenna is covered by three 120° beams The Cylindrical Lunberg lens antenna is formed by crossing the array along the axial direction. The main structure of the lens antenna unit is a dielectric cylindrical lens, a parallel metal plate waveguide structure and a feed source; patent CN102130381 proposes a partially dielectrically symmetrical filled cylindrical lens antenna. The antenna is based on the transmission law of the TE wave in the parallel plate waveguide, and the required refractive index distribution is achieved by partially filling the medium; Olivier Lafond et al. designed a paper entitled "An Active Reconfigurable Antenna at 60 GHz Based on Plate Inhomogeneous Lens and Feeders" in IEEE TRANSACTIONSONANTENNASANDPROPAGATION, VOL.61, NO.4, APRIL2013 The layered cylindrical Lunberg lens antenna is based on the medium equivalent theory, and the required Lunberg lens refractive index is obtained by changing the equivalent dielectric constant of the filling medium in the parallel plate waveguide. To sum up, the existing cylindrical Lunberg lens antennas are generally based on the parallel plate waveguide structure, and the structure itself determines that this kind of cylindrical Lunberg lens antenna is a linearly polarized antenna. However, in many practical engineering application scenarios such as satellite communication, "communication in motion" communication, anti-multipath interference communication in complex environments, etc., circularly polarized electromagnetic wave signals are usually required. In these usage scenarios that require circularly polarized signals, if a traditional linearly polarized Lunberg lens antenna is used, a circularly polarized radome needs to be added outside the antenna. After loading the circularly polarized radome, it not only increases the difficulty of antenna processing, but also brings a series of problems such as complex antenna structure, increased loss, and reduced antenna efficiency.

In view of the phenomenon that the cylindrical Lunberg lens antennas involved in the published patents and papers are mostly linearly polarized, the present invention proposes a new type of circularly polarized or double circularly polarized cylindrical Lunberg lens based on a dielectric plate waveguide Antenna, the cylindrical Lunberg lens antenna can achieve circular polarization or dual circular polarization by using a linearly polarized feed. The invention has simple structure, mature and stable processing technology, and is especially suitable for the millimeter wave frequency band.

Contents of the invention

In view of the above-mentioned technical background and use requirements, the present invention designs a novel circularly polarized and double circularly polarized cylindrical Lunberg lens antenna. The novel circular polarization and dual circular polarization cylindrical Lunberg lens antennas of the present invention are designed based on the dielectric plate waveguide structure. In the dielectric plate waveguide, the transmission characteristics of the TE wave and TM wave of the even mode are shown in formula (1) and formula (2):

$\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; v</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; T</span>}\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; v</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; K</span>}\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; p</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ \mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Where h is the propagation constant of the electromagnetic wave along the normal direction of the waveguide of the dielectric plate, β is the transmission of the electromagnetic wave along the waveguide of the dielectric plate, and P is the attenuation constant of the waveguide boundary of the dielectric plate.

Since the dielectric plate waveguide is a pure dielectric structure, compared with the parallel plate waveguide, the dielectric plate waveguide can realize the simultaneous transmission of TEO and TMO waves. Based on the transmission characteristics of the dielectric plate waveguide, a linearly polarized feed antenna is used, the polarization direction of which is at an angle of 45° to the axial direction of the cylindrical dielectric plate lens, and equal-amplitude TEO waves are simultaneously excited in the dielectric plate lens and TMO waves. It can be seen from equations (1) and (2) that the propagation constants of TEO wave and TMO wave in the dielectric plate waveguide are different. By changing the thickness distribution and size of the dielectric plate lens, the refraction required for beam focusing can be achieved. At the same time, the TEO wave and the TMO wave have a 90° phase difference when they exit the dielectric plate lens. The cylindrical Lunberg lens antenna of the present invention realizes circular polarization according to the above-mentioned principle. When it is necessary to achieve dual circular polarization, it is only necessary to replace the above linearly polarized feed with a dual linearly polarized feed, the two polarization directions are perpendicular to each other, and are clamped at 45° to the axial direction of the cylindrical dielectric plate lens horn.

The most prominent innovation of the present invention is that the use of the dielectric plate waveguide can support the transmission characteristics of TEO and TMO wave coexistence, and by adjusting the thickness distribution and size of the appropriate dielectric plate waveguide lens, the 45° linearly polarized feed source is excited ingeniously. The horizontally polarized TEO wave and the vertically polarized TMO wave realize the conversion from the cylindrical wave to the plane wave while generating a 90° phase difference between them, thereby realizing circular polarization.

Another outstanding innovation of the present invention is that it only needs to replace the feed source of the above-mentioned circularly polarized Lunberg lens antenna with a dual-polarized feed source, and the double circular pole can be realized without changing the lens part of the dielectric plate. It can effectively improve the reusability of the design.

Since the novel circularly polarized and dual circularly polarized cylindrical Lunberg lens antennas of the present invention have structural characteristics of rotational symmetry, the present invention can also be applied to the use scenario of multi-beam scanning in azimuth plane. At this time, it is only necessary to arrange the arc-shaped feed array along the circumference of the cylindrical dielectric plate waveguide lens, and adjust the spacing between the arc-shaped feed array elements according to the beam width generated by a single feed, so as to realize uninterrupted beam scanning in the azimuth plane.

At the same time, the waveguide lens part of the dielectric plate in the present invention can be machined entirely by turning and milling a cylindrical dielectric plate into a certain rotationally symmetrical cross-sectional shape, which has the advantage of simple processing. Since the cylindrical Lunberg lens of the present invention has a pure dielectric structure, the metal parallel plate of the traditional cylindrical Lunberg lens antenna is removed, so the present invention realizes the light weight of the antenna.

The embodiment of the present invention is that the electromagnetic wave radiated by the 45° linearly polarized feed or the double 45° linearly polarized feed enters the dielectric plate waveguide lens, using the transmission characteristics of the dielectric plate waveguide, when the electromagnetic wave passes through the lens, a narrow beam is formed At the same time, realize circular polarization or double circular polarization.

Description of drawings

Fig. 1 is in the specific embodiment, the three-dimensional structural diagram of the novel cylindrical Lunberg lens antenna of the present invention;

Fig. 2 is in the specific embodiment, the side view of the novel cylindrical Lunberg lens antenna of the present invention;

Fig. 3 is in the specific embodiment, the top view of the novel cylindrical Lunberg lens antenna of the present invention;

Fig. 4 is in the specific embodiment, the cylindrical Lunberg lens antenna azimuth plane circular polarization radiation pattern of the present invention;

Fig. 5 is the specific embodiment, the axial ratio near the circularly polarized main lobe of the azimuth plane of the cylindrical Lunberg lens antenna of the present invention;

Fig. 6 is a radiation pattern diagram of the double circularly polarized azimuth plane of the cylindrical Lunberg lens antenna of the present invention in a specific embodiment.

specific implementation plan

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the implementation methods and accompanying drawings.

Referring to Fig. 1, Fig. 2 and Fig. 3, novel circular polarization of the present invention and double circularly polarized cylindrical surface Lunberian lens antenna comprise and be attached to the peripheral surface of cylindrical lens and the polarization direction and lens axis are 45 ° included angles The linearly polarized feed antenna 1 (when realizing dual circular polarization, it should be replaced with a dual linearly polarized feed) and in order to meet the required refractive index and make the horizontally polarized TEO wave and the vertically polarized TMO wave generate a 90° A phase difference dielectric plate waveguide lens 2 with a certain rotationally symmetrical cross-sectional shape. According to the propagation characteristics of electromagnetic waves in the dielectric plate waveguide, the refractive index of the horizontally polarized TEO wave and the vertically polarized TMO wave in the dielectric plate waveguide is related to the thickness of the dielectric plate waveguide, and the two are in the same thickness of the dielectric plate waveguide The refractive index in is different. Therefore, the thickness distribution and radius of the cylindrical dielectric plate lens 2 can be determined according to the required refractive index of the Lunberg lens and the conditions for realizing a 90° phase difference between the TEO wave and the TMO wave when exiting the dielectric plate lens. In terms of material selection of the cylindrical dielectric plate lens 2, the dielectric plate material should follow the principle of low electromagnetic loss and stable dielectric constant, and at the same time in order to ensure the machinability of the dielectric plate lens 2, the dielectric constant should not be too high, otherwise it will be damaged. As a result, the thickness of the lens of the dielectric plate is too small, which is difficult to process. In the present invention, the plate of the dielectric plate lens 2 is designed as a cross-linked polystyrene plate with a relative permittivity of 2.56.

Fig. 4 is the azimuthal far-field radiation pattern of main polarization and cross polarization when the novel cylindrical Lunberg lens antenna of the present invention realizes right-handed circular polarization. The HFSS simulation results show that the half-power beamwidth in the azimuth plane is 3.8°. In the main radiation direction, the cross-polarization level is greater than 25dB.

Fig. 5 describes the axial ratio near the main lobe when the novel cylindrical Lunberg lens antenna of the present invention realizes right-handed circular polarization. It can be seen that the axial ratio is less than 3dB within the half-power beam width of 3.8°.

FIG. 6 shows the far-field radiation patterns in the azimuth plane of two circular polarizations when the novel cylindrical Lunberg lens antenna of the present invention realizes dual circular polarizations. The HFSS simulation results show that the half-power beamwidth in the azimuth plane is 4.3°. In the main radiation direction, the cross-polarization level is greater than 16dB.

The above is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless specifically stated, can be replaced by other equivalent or alternative features with similar purposes; all the disclosed features, or All method or process steps may be performed in any manner, except for mutually exclusive features and/or steps.

Claims (5)

1. Based on a new type of circular polarization and double circular polarization cylindrical Lunberg lens antenna, including a linear polarization feed 1 and a dielectric plate waveguide lens 2. It is characterized in that the linearly polarized feed source 1 is attached to the circumferential surface of the cylindrical dielectric plate waveguide lens 2, and the dielectric plate waveguide lens 2 is a rotationally symmetrical structure with a certain cross-sectional shape. The thickness distribution and radius of the cylindrical dielectric plate lens 2 can be determined according to the required refractive index of the Lunberg lens and the conditions for realizing a 90° phase difference between the TE0 wave and the TM0 wave when exiting the dielectric plate lens. In terms of material selection of the cylindrical dielectric plate lens 2, the dielectric plate material should follow the principle of low electromagnetic loss and stable dielectric constant, and at the same time in order to ensure the machinability of the dielectric plate lens 2, the dielectric constant should not be too high, otherwise it will be damaged. As a result, the thickness of the lens of the dielectric plate is too small, which is difficult to process. 2. Novel circular polarization as claimed in claim 1 and double circular polarization cylindrical surface Lunberian lens antenna, it is characterized in that, the polarization direction of linearly polarized feed source 1 and the normal direction of dielectric plate waveguide lens 2 are 45° ° Angle. 3. The novel circular polarization and double circular polarization cylindrical Luneberg lens antenna as claimed in claim 1 and claim 2, characterized in that, in order to realize double circular polarization, the linearly polarized feed source 1 can be replaced by a dual The two polarization directions of the linearly polarized feed are perpendicular to each other and form an included angle of 45° with the normal direction of the dielectric plate waveguide lens 2 . 4. Novel circular polarization as claimed in claim 1 and double circular polarization cylindrical surface Luneberg lens antenna, it is characterized in that, according to the transmission characteristic of dielectric plate waveguide internal wave, the required refractive index of Luneburg lens and order horizontal pole According to the requirement of 90° phase difference between the polarized TE0 wave and the vertically polarized TM0 wave, the radial thickness distribution of the dielectric plate waveguide lens 2 presents a deformed frustoconical distribution. 5. Novel circular polarization and dual circular polarization cylindrical Lunberg lens antennas as claimed in claim 1, claim 2 and claim 3, characterized in that only arcs need to be arranged along the circumference of the cylindrical dielectric plate waveguide lens For the feed array, according to the beam width generated by a single feed, adjust the spacing between arc feed array elements to realize azimuth beam scanning.