CN204103047U - A kind of millimeter-wave near-field mechanical focusing dual reflector antenna - Google Patents

Abstract

The utility model discloses a millimeter-wave near-field mechanical focusing double reflector antenna, which comprises a main reflector, a secondary reflector, and a feed source, and the wave beam emitted by the feed source is reflected by the secondary reflector to the main reflector Then shoot out; the sub-reflector can move back and forth, up and down, left and right or rotate or rotate on the moving mechanism; the curved surface shape of the main reflector is a rotating paraboloid, and the center point of the main reflector is located at the intersection of the central axis of the secondary surface and the axis of the radiation beam place. The utility model has simple structure and mature processing, which improves the axial power density and the range of action distance in the near-field area of the antenna, and at the same time can simply and quickly adjust the position of the maximum power density in a larger area, that is, under the same input power condition, the maximum power density of the axis Significantly improved and position adjustable over a larger area; increases the range to reach the effective power threshold.

Description

A millimeter-wave near-field mechanically adjustable dual-reflector antenna

technical field

The utility model relates to the technical field of millimeter-wave antennas, in particular to a millimeter-wave double-reflection-surface shaped antenna whose radiation beams can be focused in a near-field area.

Background technique

The dual-reflector antenna consists of three parts: the main reflector, the sub-reflector and the feed, including Cassegrain, Gregory and ring-focus antennas. Compared with other antennas, it has the characteristics of low sidelobe, low cross polarization, and high gain. It has been widely used in precision tracking and measurement radars in missile ranges since the 1960s. Such as the AN/FPQ-6 radar and Qudex radar in the United States, and the JLA-1 in France. At the same time, compared with the centimeter wave band, the feeder system working in the millimeter wave frequency band has a large loss. In order to shorten the feeder line of the feed source, a general high-power millimeter wave system uses a double reflector antenna with the feed source behind the antenna as the radiation system.

Large-aperture antennas have strong diffraction coherence in the near-field region (Fresnel region), and there are many Fresnel peaks in the beam distribution along the axis, as shown in Figure 1. In recent years, in the application fields of millimeter-wave short-range communication, millimeter-wave human body imaging, millimeter-wave wireless energy transmission, and millimeter-wave plasma heating in the ITER plan, more and more millimeter-wave antenna applications are focused on the Fresnel of the antenna. At the same time, they all hope to obtain greater axial power density under the same power source. However, the high-power millimeter-wave antennas that have been developed abroad all adopt the non-focused radiation mode with the focus at infinity, which makes the maximum axial power density (that is, the last Fresnel peak) of the mouth-surface radiation field in the near-field area relatively low. The range of distances to reach the effective power threshold is small.

The document with the application number (2014102572537) discloses a near-field beam-focusing millimeter-wave double-reflector antenna, which improves the power density on the near-field axis and increases the range of near-field action distance, but in practical applications, When the application environment parameters change and the position of the maximum power density point needs to be adjusted or the distance range to reach the effective power threshold needs to be wider, it is necessary to move the system as a whole, or replace a new antenna system or add another antenna system, which greatly increases the System cost and implementation difficulty, such as in the process of biomedicine and plasma heating, it is necessary to move or rotate the position of the maximum power density of the millimeter wave heated according to the actual physiological characteristics and the test distribution of plasma temperature to achieve the best effect. However, using the original fixed-focus focusing method requires adding an antenna system or adopting a very complicated mechanical structure to realize the overall movement of the whole system, which is extremely costly and technically difficult. At present, in millimeter-wave near-field antennas, non-focusing antennas are used, and the position of the maximum power density is difficult to adjust. Therefore, a millimeter-wave focusing antenna system that can easily adjust the position of the focus point is needed.

Utility model content

The purpose of the utility model is to improve the antenna radiation near-field axis power density and simply and quickly adjust the maximum power density position, increase the range of the near-field action area, and provide a millimeter-wave near-field mechanically adjustable double-reflector antenna. By shaping the curved surfaces of the main and sub-reflectors of the dual-reflector antenna, the beam fed by the feed can produce a focusable field amplitude distribution and phase distribution on the main surface of the antenna, and through the relative position of the antenna sub-surface The small adjustment of the main surface can realize the change of the amplitude and phase distribution of the main surface. The beam radiated by the main surface and the surface field is focused to the design area in the near field, which improves the axial power density in the near field area, and realizes a wide range of changes in the position of the focus point through the small adjustment of the position of the antenna subsurface, which solves the problem of the current millimeter wave In some applications in the near field, the maximum value of the axial power density is low, the position of the maximum power density is extremely difficult to adjust, and the range of the area where the effective power threshold is reached is relatively small.

A millimeter-wave near-field mechanical focusing double reflector antenna, including a main reflector, a secondary reflector and a feed source, the beam emitted by the feed source is reflected by the secondary reflector to the main reflector and then emitted; the main reflector The curved surface shape of the reflective surface is a paraboloid of revolution, and the center point of the main reflective surface is located at the intersection of the central axis of the secondary surface and the axis of the radiation beam; On the exit axis of the feed source; the feed source is arranged near the real focus of the sub-reflector; the focus of the main reflector is close to another real focus of the antenna sub-surface hyperboloid; the main reflector, the sub-reflector The surface and the feed source are set on the same support, and the feed source and the main reflector are fixed on the support to keep the position unchanged; the support is provided with a movement mechanism, and the secondary reflection surface is arranged on the movement mechanism, and the secondary reflection surface can be placed on the movement mechanism Move up and down, up and down, left and right, or rotate.

Further, the main reflective surface is a circular symmetrical structure or an elliptical symmetrical structure.

Further, both the main reflective surface and the secondary reflective surface are conductive surfaces.

Further, the conductive surface is a fully conductive metal structure; or is a non-metallic material, and the surface of the non-metallic material is coated with a metal layer or conductive paint.

A millimeter-wave near-field mechanically adjustable double-reflector antenna, including a main reflector, a sub-reflector, a sub-reflector movement mechanism and a feed source, and the beam emitted by the feed source is reflected by the sub-reflector to the main reflector Re-emit; the curved surface shape of the main reflector is a paraboloid of revolution, and the center point of the main reflector is located at the intersection of the secondary surface exit central axis and the radiation beam axis; the curved surface of the secondary reflector is an ellipsoid, and the secondary reflector is a circle Symmetrical structure, the center of the circle is located on the output axis of the feed source; the feed source is arranged near the real focus of the secondary reflection surface; the focus of the main reflection surface is close to the other focus of the ellipsoid of the antenna secondary surface.

The auxiliary reflecting surface moving mechanism in the utility model is used for bearing, moving driving, and positioning the antenna auxiliary reflecting surface. Its support structure can be mechanical structures such as guide rails and support rods; its motion drive can be electromagnetic devices, motor-driven gears, hinges, screws, etc., hydraulic pressure, high-pressure gas, vacuum adsorption and other mechanical drives, and its step accuracy depends on the actual application Sure. The material of the motion mechanism is not limited, and may be metal, non-metal and other materials.

In the utility model, the whole antenna system is divided into two types, one is a Cassegrain antenna, and the other is a Gregorian antenna. The curved surface of the secondary reflector is a hyperboloid of rotation, and the feed is placed on the real focus of the hyperboloid, then the entire antenna system is a Cassegrain antenna. The focus of the paraboloid of the main reflector is the other real focus of the hyperboloid of the secondary reflector Coincident; the surface of the sub-reflector is an ellipsoid, and the antenna feed is set on one focus of the ellipsoid, then the antenna system is a Gregorian antenna, and the focus of the parabola of the main reflector coincides with the other focus of the ellipsoid of the antenna reflection sub-surface . When the axis of the radiation beam is parallel to the normal of the antenna surface, the main reflector has a circular symmetric structure; when the axis of the radiation beam has a certain angle with the normal of the antenna surface, the main reflector has an elliptical symmetric structure. The central point of the main reflecting surface is located at the intersection of the central axis of the secondary surface exiting and the axis of the radiation beam.

In the utility model, the curved surface shapes of the main reflective surface and the secondary reflective surface are precisely shaped, wherein the shaped shape of the secondary reflective surface controls the amplitude distribution of the surface field of the main surface, and the shaped shape of the main reflective surface controls the main surface. Phase distribution of the oral surface field. The main reflective surface and the secondary reflective surface are conductive metal surfaces, which can be made of all metals such as aluminum and copper or non-metallic materials, and then the surface is coated, electroplated with a metal layer or conductive paint.

The millimeter-wave double-reflector antenna with near-field beam focusing of the utility model works in the millimeter-wave band, and its working principle is: the input millimeter-wave signal enters the double-reflector antenna system through the radiation of the feed source; the millimeter distribution of the radiation from the feed source After being reflected by the sub-reflector, it illuminates the main reflector. The shape-forming structure of the sub-reflector controls and adjusts the amplitude distribution of the millimeter-wave beam input by the feed source (Antenna Engineering Handbook, edited by Lin Changlu, p610); reflected by the sub-reflector The formed millimeter-wave distribution is reflected by the main reflector to form the distribution of the main antenna aperture in Figure 1. The shaped structure of the main reflector has different optical path lengths for the input millimeter-wave beams. After being reflected by the main reflector, the in-phase beam on the antenna surface forms a concave phase distribution on the antenna surface (that is, the beam axis is 0°, and the phase angle increases with the distance from the center); the amplitude and phase distribution of the antenna surface are close to the antenna A focused beam spot is formed in the field area, and the axial power density in the focused beam spot area is increased, and the distance range to reach the effective power threshold is increased. When the mechanical movement mechanism fine-tunes the position of the sub-reflector, the amplitude and phase of the beam reflected by the sub-reflector will change, and then the phase distribution of the main reflector surface and the position of the concave center point of the phase distribution will change. The self-amplification effect eventually leads to a large-scale change in the near-field focus position of the antenna.

In summary, due to the adoption of the above technical solution, the beneficial effects of the utility model are:

The existing millimeter-wave near-field antennas are non-focusing antennas, the maximum value of the axial power density is relatively low, the area where the effective power threshold is reached is relatively small, and the position of the maximum power density can be adjusted by replacing or moving the system. High, slow time, large space requirements, and difficult technical implementation. The utility model can effectively solve this difficult problem by simply adding a pair of reflecting surface movement mechanisms on the basis of the focused shaped double reflecting surface antenna. At the same time, the rapid adjustment of the maximum power density in a larger area can be realized through the small adjustment of the position of the antenna sub-reflector. In this way, compared with the existing maximum power density adjustment structure, the structure is simple, the processing is mature, fast, and the space requirement is small. low cost. That is to say, in the case of the same input power, the maximum power density of the axis is greatly improved and its position can be adjusted in a larger area, which increases the range of reaching the effective power threshold.

Description of drawings

The utility model will be explained by way of example and with reference to the accompanying drawings, wherein:

Figure 1 is a distribution diagram of the near-field axis of the existing antenna system;

Figure 2 is a schematic diagram of the composition of the utility model millimeter-wave near-field mechanical focusing double-reflector antenna system;

Fig. 3 is a diagram of the Cassegrain type near-field mechanical focusing double reflector antenna of the present invention;

Fig. 4 is the electric field distribution diagram of the near-field beam profile of the utility model;

Fig. 5 is a power density distribution diagram of the near-field beam axis of the utility model;

Figure 6 is the FEKO simulation beam characteristics (electric field distribution);

Fig. 7 is a diagram of the relationship between the focus point and the moving distance of the secondary surface position;

In the figure: 1 is the feed source, 2 is the sub-reflector, 2` is the moving sub-reflector, 3 is the main reflector, 4 is the surface field of the main reflector, 5 is the radiation beam, and 6 is the shaped main reflector , 7 is a shaped sub-reflective surface, 8 is a focusing beam spot.

Detailed ways

All features disclosed in this specification, or steps in all methods or processes disclosed, may be combined in any manner, except for mutually exclusive features and/or steps.

As shown in Figure 2, the system schematic diagram of the double reflector antenna described in the present invention, the near-field beam focusing millimeter wave antenna system is composed of three main components: the feed source, the secondary reflector and the main reflector, the feed source passes through After being reflected by the secondary reflector, it is reflected from the main reflector. The surface field distribution of the main reflector is perpendicular to the outgoing direction of the feed source, and the axis of the radiation beam of the surface field can form any angle with the axis of the feed source.

In this facility example, a set of near-field beam-focusing millimeter-wave antennas with an aperture of 342.4 mm is designed, which is a Cassegrain antenna. Figure 3 is the longitudinal section of the antenna system (y=0), as shown in Figure 3: the focused beam exits in the horizontal direction; the feeder enters the Gaussian beam, the equivalent phase center is at (0,0,0), and the power is 1W; The field amplitude distribution of the main surface of the antenna is a parabolic distribution. The antenna is a rotating paraboloid with a diameter of 0.91m; the secondary surface is a rotating hyperboloid with a circular symmetrical structure and a diameter of 0.063m; the antenna system is made of aluminum.

Figure 4 shows the obtained near-field beam profile electric field distribution (unit V/m), and the beam is well focused in the near-field area. Figure 5 shows the corresponding axial power density distribution (W/cm ² ), where the star line corresponds to the axial power density distribution of the focused field with a focal point of 2.66m, and the smooth line corresponds to the axial power density of an unfocused field with a focal point of 3000000m distributed. As shown in Figure 5, the maximum value of the power density is 0.0037W/cm ² when not focusing; the maximum value after focusing is 0.1113W/cm ² ; when 0.04 W/cm ² is used as the action threshold, the effective effect of the focusing antenna The range is 2.08m~3.88m, and the non-focus antenna has no effective range.

Figure 6 shows the simulation results of the designed focused beam antenna in FEKO software. Since the space to be simulated is too large relative to the radiation wavelength, the physical optics method is used for simulation. It can be seen from the figure that the near-field region of the radiation beam is well focused, and its axial power density distribution is consistent with Figure 4 and Figure 5.

In order to realize the adjustment of the focus point, the position of the feed source and the main surface of the antenna is fixed in the FEKO software, and the sub-surface of the antenna is moved back and forth along the angle of -28.5° with the outgoing direction of the millimeter wave to obtain the relationship between the focus point of the beam and the moving distance of the sub-surface As shown in Figure 7, the position of the secondary surface at 0 mm is the position of the secondary surface shown in Figure 6 . It can be seen from Figure 7 that the moving range of the secondary surface is -16mm~45mm, and the moving distance of the focus point is about 3m.

The utility model is not limited to the aforementioned specific embodiments. The utility model extends to any new feature or any new combination disclosed in this specification, as well as the steps of any new method or process or any new combination disclosed. the

Claims (4)

1. a millimeter-wave near-field mechanical focusing dual reflector antenna, comprises primary reflection surface, subreflector and feed, and the wave beam that described feed is launched reflexes to after primary reflection surface through subreflector and penetrates; The curve form of described primary reflection surface is the paraboloid of revolution, and the central point of primary reflection surface is positioned at minor face outgoing central axis and radiation beam crossing point of axes place; Described subreflector curved surface is the hyperboloid of revolution, and subreflector is circle symmetrical structure, and the center of circle is positioned on described feed outgoing axis; Described feed is arranged near the real focus of subreflector; The focus of described primary reflection surface is close with antenna minor face another real focus bi-curved; Described feed axis becomes with primary reflection surface radiation beam axis spends angle arbitrarily; It is characterized in that described primary reflection surface, subreflector and feed arrange on same support, it is constant that feed and primary reflection surface are fixed on holding position on support; Described support is provided with motion, and subreflector is arranged on motion, subreflector can on motion before and after, up and down, to move left and right or in rotary moving or rotate.

2. a kind of millimeter-wave near-field mechanical focusing dual reflector antenna according to claim 1, is characterized by described primary reflection surface for justifying symmetrical structure or being ellipsometry structure.

3. a kind of millimeter-wave near-field mechanical focusing dual reflector antenna according to claim 1, is characterized by described primary reflection surface and subreflector is conducting surface.

4. a kind of millimeter-wave near-field mechanical focusing dual reflector antenna according to claim 3, it is characterized by described conducting surface is full conductive metal structure; Or be nonmetallic materials, the coating of its non-metal material surface, electroplated metal layer or conductive paint.