CN110504547B

CN110504547B - Series-fed waveguide slot frequency scanning antenna with large scanning angle in limited bandwidth

Info

Publication number: CN110504547B
Application number: CN201910673117.9A
Authority: CN
Inventors: 杨明磊; 胡晓宇; 陈思思
Original assignee: Xian Cetc Xidian University Radar Technology Collaborative Innovation Research Institute Co Ltd
Current assignee: Xian Cetc Xidian University Radar Technology Collaborative Innovation Research Institute Co Ltd
Priority date: 2019-07-24
Filing date: 2019-07-24
Publication date: 2021-02-02
Anticipated expiration: 2039-07-24
Also published as: CN110504547A

Abstract

A series-fed waveguide slot frequency scanning antenna with a large scanning angle in a limited bandwidth comprises a waveguide slow wave structure, a slot plate and a horn structure, wherein the waveguide slow wave structure consists of a linear waveguide section and an elbow connected with the linear waveguide section, the elbow is a 180-degree elbow, and the elbow is provided with different chamfers; the horn structure consists of horn mouths and partition plates, wherein N +1 partition plates corresponding to N gaps are arranged between the horn mouths, and each partition plate is respectively positioned above the centers of adjacent gaps in the gap plates and integrated with the horn mouths; energy is input from one end of the waveguide slow wave structure and is radiated to the free space through the horn structure, and the other end of the waveguide slow wave structure is connected with the matched load. The loss is reduced by optimizing the waveguide slow wave structure and the horn structure. The working frequency band is 15.7 GHz-17.2 GHz, and the azimuth scanning angle can reach-65-45 degrees. The invention can be applied to different wave bands such as microwave and millimeter wave and the like by zooming the structural parameters.

Description

Series-fed waveguide slot frequency scanning antenna with large scanning angle in limited bandwidth

Technical Field

The invention belongs to the technical field of microwave antennas, and particularly relates to a series-fed waveguide slot frequency scanning antenna with a large scanning angle in a limited bandwidth, which belongs to the technical field of waveguide slot antennas and can be used in the field of wireless communication such as radar satellites.

Background

The requirement that the radar antenna lobe can be quickly and flexibly scanned cannot be realized only by mechanical movement of the antenna, so that an electric scanning antenna technology is introduced into the field of radars. The current antenna electric scanning technology mainly comprises phase scanning, frequency scanning, time delay scanning, electronic feed switch scanning and the like. Of which phase scanning and frequency scanning are more applied. The feeding phase of each unit in the antenna array is directly controlled by a phase shifter to realize beam scanning, so that a common phased array antenna is formed. When the number of phased array units is large, the whole system is complex and the manufacturing cost is high. The phase relation among the antenna units is changed by changing the working frequency of the antenna, and the change of the lobe direction can also be realized, namely, the frequency scanning antenna is formed.

The frequency scanning antenna is usually a linear array or an area array structure composed of waveguide slots or microstrip patches. The waveguide slot antenna can radiate energy by slotting on the waveguide and can be divided into a traveling wave type slot array and a standing wave type slot array. When the working frequency of the standing wave type slot array is changed, the performance is sharply reduced, and the standing wave type slot array cannot be used as a frequency scanning antenna. When the working frequency of the traveling wave type slot array is changed, phase differences exist among the slot radiation waves, and the equiphase surfaces of the antenna array are changed, so that the beam direction of the antenna can be adjusted by changing the frequency. However, the beam scanning angle of the antenna in a narrow frequency band is small, and wide-angle beam scanning of the antenna in a narrow frequency band cannot be achieved. And when the number of antenna array elements is large, reflected waves are superposed in phase at a central frequency point, and the loss at the central frequency point is huge, so that the antenna is unavailable.

For example, a frequency scanning antenna is proposed in a patent of 'low-loss frequency scanning antenna planar array based on a hybrid feed structure within a limited bandwidth' (application number: CN201811256266.7, publication number: CN109193152A) by yaokai radar technology limited company, and the frequency scanning array is composed of a plurality of parallel sub-arrays, including a double-layer microstrip patch array, a metal floor, an E-plane curved waveguide, a waveguide slot and microstrip line electromagnetic coupling feed structure, a waveguide power divider, and a 180-degree elbow. By adopting a plurality of parallel sub-arrays, the waveguide slow wave line structure coupled by narrow-edge gaps is used as a feeder line and is applied to the array through a hybrid coupling feed structure. The scanning angle is-30.5-29.5 degrees in the required working bandwidth. The scanning range is small and the feed structure is complex.

For example, Nanjing university of science and engineering in the patent of its application entitled "a large-angle hybrid feed frequency scanning antenna based on standard rectangular waveguide" (application No. CN201711328624.6, published as CN108155462A) proposes a frequency scanning antenna, which comprises a standard rectangular waveguide slow wave line, a lower layer microstrip, a middle foam layer and an upper layer microstrip which are arranged in sequence from top to bottom, wherein the standard rectangular waveguide slow wave line comprises a straight waveguide section and an elbow connecting the straight waveguide section, and a slit is arranged at the center of the straight waveguide section. The scanning angle range of the main beam of the antenna is-46.3-45.5 degrees. The antenna adopts the micro-strip layer, the foam layer and the dielectric plate to realize large-angle scanning of the waveguide slot antenna, and the structure is complex.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a series-fed waveguide slot frequency scanning antenna with a large scanning angle in a limited bandwidth, which is used for solving the technical problems of small scanning angle and complex structure of the frequency scanning antenna.

In order to achieve the purpose, the series-fed waveguide slot frequency scanning antenna with a large scanning angle in a limited bandwidth comprises a waveguide slow wave structure, a slot plate and a horn structure, wherein the waveguide slow wave structure consists of a linear waveguide section and an elbow connected with the linear waveguide section, the elbow is a 180-degree elbow, and the elbow is provided with different chamfers; the gap plate covers the waveguide slow wave structure, N gaps are arranged at the positions corresponding to the centers of the linear waveguide sections, the horn structure consists of horn mouths and partition plates, N +1 partition plates corresponding to the N gaps are arranged between the horn mouths, and each partition plate is respectively positioned above the centers of the adjacent gaps in the gap plate and integrated with the horn mouth; the horn structures are symmetrically distributed about the Z axis.

Further, the height of the partition is represented by h1, the thickness is represented by hou, wherein h1 is 49.5 mm-50.5 mm, and hou is 2.5 mm-2.7 mm.

Further, the chamfer radius of the elbow connecting the linear waveguide section changes along with the change of the deflection angle of the slit, and the chamfer radius is represented as R, wherein R is 7.3 mm-7.85 mm.

Compared with the prior art, the invention has the following advantages:

1. the horn structure adopted by the invention consists of horn mouths and partition plates, wherein N +1 partition plates corresponding to N gaps are arranged between the horn mouths, and each partition plate is respectively positioned above the centers of adjacent gaps in the gap plates and is integrated with the horn mouths; the horn structure is only used for making up the defects of the waveguide gap frequency scanning antenna with the slow wave structure, the technical problem that the waveguide gap frequency scanning antenna in the prior art is complex in structure is solved, and a series feed mode is adopted, so that the feed structure is simple.

2. The horn structure adopted by the invention consists of the horn mouths and the partition plates, wherein N +1 partition plates corresponding to N gaps are arranged between the horn mouths, and the partition plates are respectively positioned above the centers of adjacent gaps in the gap plates and are integrated with the horn mouths, so that mutual coupling among the gap units is reduced, the electrical parameters of the antenna are kept smooth in the whole frequency band, and wide-angle scanning under the condition of limited relative bandwidth is realized.

3. According to the invention, the chamfer radius of the elbow connecting the linear waveguide section is optimized, and the elbows with different chamfer radii are used according to different slit deflection angles, so that the return loss of the antenna at the central frequency point is reduced, and the standing-wave ratio of the antenna at the central frequency point is reduced.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of a waveguide slow wave structure of the present invention;

FIG. 3 is a top view of the horn configuration of the present invention;

FIG. 4 is a front view of the horn configuration of the present invention;

FIG. 5 is a graph of the simulation results of return loss S11 of the present invention;

FIG. 6 is a graph of standing wave ratio VSWR simulation results of the present invention;

FIG. 7 is a graph of the radiation efficiency simulation results of the present invention;

FIG. 8 is the E-plane directional diagram of the present invention at the frequency points of 15.7GHz, 16.5GHz and 17.2 GHz;

FIG. 9 is the H-plane directional diagram of the present invention at 16.5GHz frequency point;

Detailed Description

The invention is described in further detail below with reference to the attached drawing

Example 1

With reference to fig. 1, 2, 3 and 4

A series-fed waveguide slot frequency scanning antenna with a large scanning angle in a limited bandwidth comprises a waveguide slow wave structure 1, a slot plate 2 and a horn structure 3, wherein the waveguide slow wave structure 1 consists of a linear waveguide section 1.1 and an elbow 1.2 connected with the linear waveguide section, the elbow 1.2 is an elbow of 180 degrees, and the elbow is provided with different chamfers; the gap plate 2 covers the rectangular slow wave structure 1, N gaps are arranged at the positions corresponding to the centers of the linear waveguide sections 1.1, the horn structure 3 is composed of horn mouths 3.1 and partition plates 3.2, N +1 partition plates 3.2 are arranged between the horn mouths 3.1, each partition plate 3.2 is respectively positioned above the centers of the adjacent gaps in the gap plate 2, and the horn mouths 3.1 and the partition plates 3.2 form a whole; the horn structures 3 are symmetrically distributed about the Z-axis.

In a waveguide slot frequency scanning antenna, a slow wave structure is generally used to realize large-angle scanning, but in the design of the slow wave structure frequency scanning antenna, the bandwidth, the scanning angle and the loss are in a mutually restricted relationship. The narrower the bandwidth, the longer the slow wave lines used to achieve wide angle scanning, and the corresponding losses increase.

The inventive antenna employs taylor weighting. The radiation efficiency is different due to different deflection angles of the gaps, and the radiation efficiency of each gap is subjected to Taylor distribution by adjusting the deflection angle of each gap. The slot deflection angles are different and the return loss through a 180 ° bend of the same chamfer radius is also different. Because the reflected waves of the waveguide slot frequency scanning antenna are superposed in phase at the central frequency point, the return loss at the central frequency point is very large, the efficiency is very low, and the antenna cannot be used, so that the return loss of the antenna at the central frequency point can be reduced by adjusting the chamfer radius of the 180-degree elbow according to different slot deflection angles.

The antenna radiation field is formed by combining the radiation fields of all the slot units, and the mutual coupling of the adjacent slot units can cause the performance of the antenna to be reduced, and even cause the antenna to be unusable when the frequency is changed. Through adding the baffle in loudspeaker, can reduce the mutual coupling between each gap unit, reduce the frequency change and to the influence that antenna standing wave ratio brought, make antenna standing wave ratio more level and smooth in whole frequency channel, available at full frequency channel.

The height of the partition board 3.2 is h1, the thickness is hou, wherein h1 is 49.5 mm-50.5 mm, hou is 2.5 mm-2.7 mm. In the present invention, h1 is preferably 49.7mm, and hou is preferably 2.6 mm.

The chamfer radius of the elbow 1.2 connecting the linear waveguide sections changes along with the change of the deflection angle of the slit, and the radius is expressed as R, wherein R is 7.3 mm-7.85 mm. In the present invention, R is preferably 7.7 mm.

Example 2

The height of the partition board 3.2 is h1, the thickness is hou, wherein h1 is 49.5 mm-50.5 mm, hou is 2.5 mm-2.7 mm. In the present invention, h1 is 49.5mm, and hou is preferably 2.5 mm.

The chamfer radius of the elbow 1.2 connecting the linear waveguide sections changes along with the change of the deflection angle of the slit, and the radius is expressed as R, wherein R is 7.3 mm-7.85 mm. In the invention, R is 7.3 mm.

Example 3

The height of the partition board 3.2 is h1, the thickness is hou, wherein h1 is 49.5 mm-50 mm, hou is 2.5 mm-2.7 mm. In the present invention, h1 is 50mm, and hou is preferably 2.7 mm.

The chamfer radius of the elbow 1.2 connecting the linear waveguide sections changes along with the change of the deflection angle of the slit, and the radius is expressed as R, wherein R is 7.3 mm-7.85 mm. In the invention, R is 7.85 mm.

The present invention is further described in detail in connection with simulation experiments

Refer to fig. 5, 6, 7, 8 and 9

Simulation content and analysis:

the above examples were simulated and calculated in the range of 15.7GHz to 17.2GHz using the commercial electromagnetic simulation software CST MICROWAVE STUDIO 2019.

Fig. 5 is a graph of simulation results of return loss S11 of the present invention. As shown, the abscissa is frequency in GHz and the ordinate is return loss in dB; the return loss S11< -10dB in the full frequency band is good in performance, and the return loss S11 at the central frequency point is the largest and is-10 dB.

FIG. 6 is a graph of the results of a standing wave ratio VSWR simulation of the present invention. As shown in the figure, the abscissa is frequency, the unit is GHz, and the ordinate is standing-wave ratio; the standing wave ratio VSWR <2 in the full frequency band. Except that the standing-wave ratio at the central frequency point reaches 1.9, the standing-wave ratios at the other frequency points are all less than 1.5, and the performance is good.

Fig. 7 is a graph of the simulation result of the radiation efficiency of the present invention. As shown, the abscissa is frequency in GHz and the ordinate is radiation efficiency in dB; the radiation efficiency is lower than that of other frequency points due to higher loss at the central frequency point, but the difference is not more than 1 dB; the difference of the radiation efficiency of other frequency points except the central frequency point is not more than 0.4dB, the curve is stable, and the antenna can be normally used in the full frequency band.

FIG. 8 is a simulation diagram of E-plane directions of the frequency points of 15.7GHz, 16.5GHz and 17.2 GHz. The abscissa is angle in degrees, and the ordinate is gain in dBi;

as shown in fig. 8(a), at 15.7GHz, the antenna beam is pointed at-63.3 °, the 3dB beamwidth is 4.5 °, the sidelobe level is-23.5 dB, and the gain is 26.4 dBi;

as shown in fig. 8(b), at 16.5GHz, the antenna beam is pointed at 0.8 °, the 3dB beamwidth is 2.4 °, the sidelobe level is-22.1 dB, and the gain is 30 dBi;

as shown in fig. 8(c), at 17.2GHz, the antenna beam is pointed at 46.3 °, the 3dB beamwidth is 4 °, the side lobe level is-28.2 dB, and the gain is 29 dBi.

FIG. 9 is a simulation diagram of the H-plane direction of the frequency point of 16.5GHz in the invention. As shown, the abscissa is angle in degrees and the ordinate is gain in dBi; the 3dB beamwidth is 11.6 degrees, the sidelobe level is-21.7 dB, and the gain is 30 dBi. The beam width in the elevation dimension is about 10 deg..

The antenna is designed, the working frequency range is 15.7-17.2 GHz, the horizontal scanning angle can reach 110 degrees, the 3dB beam width is 2.5 degrees at the center of a frequency band, 4.5 degrees at two ends of the frequency band, the level of a side lobe is less than-20 dB, the gain is greater than 25dBi, the scanning angle of the antenna is increased under the condition of limited relative bandwidth, and the performance is good.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A series-fed waveguide slot frequency scanning antenna with a large scanning angle in a limited bandwidth comprises a waveguide slow wave structure (1), a slot plate (2) and a horn structure (3), wherein the waveguide slow wave structure (1) consists of a linear waveguide section (1.1) and an elbow (1.2) connected with the linear waveguide section, and the elbow (1.2) is an elbow of 180 degrees; the slot plate (2) covers the waveguide slow wave structure (1), and N slots are arranged at the positions corresponding to the centers of the linear waveguide sections (1.1), and the slot plate is characterized in that the elbow (1.2) is provided with different chamfers, the chamfer radius of the elbow (1.2) is changed along with the change of the deflection angle of the slots, and the chamfer radius is represented as R, wherein R is 7.3-7.85 mm; the horn structure (3) consists of horn mouths (3.1) and partition plates (3.2), wherein N +1 partition plates (3.2) corresponding to N gaps are arranged between the horn mouths (3.1), and each partition plate (3.2) is respectively positioned above the centers of adjacent gaps in the gap plates (2) and forms a whole with the horn mouths (3.1); the horn structures (3) are symmetrically distributed around the Z axis.

2. The slot frequency scanning antenna with series fed waveguide of large scan angle in limited bandwidth as claimed in claim 1, wherein the height of the partition (3.2) is represented by h1 and the thickness is represented by hou, wherein h1 is 49.5 mm-50 mm and hou is 2.5 mm-2.7 mm.