CN214797741U

CN214797741U - Broadband wide-angle scanning open waveguide phased array antenna

Info

Publication number: CN214797741U
Application number: CN202120507707.7U
Authority: CN
Inventors: 梁修业; 关放; 黄浩; 张喆; 曾建平; 刘晓晗; 资剑
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2021-11-19
Anticipated expiration: 2031-03-10

Abstract

The utility model belongs to the technical field of the antenna, specifically be an opening waveguide phased array antenna of wide angle scanning of broadband. The array is formed by arranging rectangular open waveguide antenna units in a regular triangular grid. And a surface modulation structure is loaded at the array aperture and comprises a pyramid-shaped medium convex structure and a conical metal side wall. The pyramid-shaped medium bulge is used as an impedance gradual change structure and is used for realizing wide-angle scanning impedance matching; the tapered metal side wall is used as an electromagnetic band gap structure and is used for generating a surface wave band gap and inhibiting a scanning blind spot in a working frequency band. The array can realize the scanning of the main plane more than +/-65 degrees within 40 percent of the working bandwidth, and has compact structure and high reliability.

Description

Broadband wide-angle scanning open waveguide phased array antenna

Technical Field

The utility model belongs to the technical field of the antenna, concretely relates to opening waveguide phased array antenna.

Background

The metal waveguide antenna has a simple structure, low loss, high gain, high reliability, large power capacity, convenient processing and other excellent characteristics, so that the metal waveguide antenna is widely applied to the fields of radar, communication, radio astronomy and the like. The waveguide antenna may be used as a high-gain fixed beam array antenna by forming a slot array antenna by slotting a metal side wall thereof, or may be used to form a frequency sweep in one dimension or a phase sweep by a plurality of waveguides side by side. However, the slot antenna has a narrow operating bandwidth due to its strong resonance characteristic, and in addition, it is difficult to form two-dimensional phase control scanning.

Phased array antennas have found widespread use in military and civilian applications in recent years due to their high data rates, fast and accurate beam agility, and other advantages. Unlike the slotting of the waveguide side walls, the two-dimensional phased array antenna can be formed by arranging the open waveguides two-dimensionally. However, when the waveguides are formed into an array, the characteristics of the antenna are greatly different from those of a single antenna due to the mutual coupling effect. On one hand, the mutual coupling can cause the active impedance to change greatly when the array is scanned at a large angle, which causes the impedance mismatch of the input port and seriously affects the radiation efficiency. On the other hand, due to the existence of the surface wave mode at the interface of the waveguide, the frocky mode and the surface wave mode are strongly coupled under a specific angle, so that a scanning blind spot is caused, which is represented by complete mismatch of the impedance of the antenna port, and the active reflection coefficient is close to 1. Over the years, many approaches have been tried to improve the broadband wide angle scanning capability of waveguide arrays, such as the use of metal matching films, dielectric plug loading, wide angle impedance matching layers, and the like. These methods can only achieve wide-angle impedance matching of the array within a narrow bandwidth, wherein the use of the dielectric coating further aggravates the surface wave effect of high frequency, so that the scanning blind spot moves to low frequency, thereby affecting the scanning performance of the array.

SUMMERY OF THE UTILITY MODEL

In order to solve the deficiencies of the prior art, the utility model provides a wide angle scanning open waveguide phased array antenna of broadband of surface structure modulation can solve array wide angle scanning impedance mismatch problem and the scanning blind spot problem that arouses by the surface wave simultaneously.

The utility model provides a wide angle scanning open waveguide phased array antenna of broadband, M N's two-dimensional array (M, N equal or unequal) that is arranged by a plurality of rectangle open waveguide antenna units in regular triangle grid form; the array main body adopts a metal structure, and a dielectric material is filled in the array main body. The basic shape of the antenna unit is a rectangular cylinder which is composed of three sections, and the antenna unit comprises the following components in sequence from top to bottom: the surface modulation structure, the rectangular waveguide with the medium filling speed and the feed network. The antenna elements are excited to feed at the bottom through coaxial connectors, and the bottom of the array is fixed by a metal floor.

The array in the utility model adopts regular triangle grid arrangement, which means that in the array, in the same row direction, the antenna units are arranged in sequence; the central axes of the adjacent three antenna units are distributed in a regular triangle between the two adjacent rows, and the positions of the antenna units in the two rows are flush; as shown in fig. 5. The arrangement mode of the array antenna can increase the aperture of the waveguide as much as possible and reduce the cut-off frequency of the waveguide without introducing grating lobes;

in the rectangular waveguide, the dielectric filling block is made of a low-loss dielectric material with the dielectric constant larger than 1;

the utility model discloses in, rectangle opening waveguide antenna is singleThe element is a single-wire polarized working antenna, and the main mode is TE₁₀Mode(s).

The utility model discloses in, the surface modulation structure, for the utility model discloses a core contains protruding structure of pyramid type medium and triangle-shaped metal lateral wall. Here, the pyramid-shaped dielectric protrusion structure is actually a quadrangular pyramid, and the bottom of the quadrangular pyramid is a rectangle matched with the rectangular waveguide; the metal side wall on one side of the wide side of the quadrangular pyramid is two isosceles triangles (the bottom side of the isosceles triangle is 1/2 of the length of the wide side of the quadrangular pyramid) which are arranged in parallel in the same structure, and the metal side wall on one side of the narrow side of the quadrangular pyramid is an isosceles triangle (the bottom side of the isosceles triangle is the same as the length of the narrow side of the quadrangular pyramid).

In the surface modulation structure, the height of the pyramid-type dielectric convex structure and the height of the triangular metal side wall are about the same and are about half wavelength of the central frequency.

The pyramid-shaped medium bulge is used as an impedance gradual change structure and is used for realizing wide-angle scanning impedance matching; the triangular metal side wall is used as an electromagnetic band gap structure and is used for generating a surface wave band gap and inhibiting a scanning blind spot in a working frequency band. The height of the pyramid-shaped dielectric raised structures and the triangular metal sidewalls is critical, and the array can achieve optimal performance when the heights are about the same and are about half the wavelength of the center frequency.

The utility model discloses in, feed network contains coaxial input section, mode conversion section and impedance transformation section triplex. The coaxial input section can be realized by a standard SMP coaxial connector; the mode conversion section comprises a round coaxial line inner conductor, a square coaxial line inner conductor and a ridge adaptation section and is used for realizing the conversion from a TEM mode in the round coaxial line to a TEM mode in the square coaxial line and further realizing the conversion to TE through the ridge adaptation section₁₀Smooth transition of the mode; the impedance matching section is realized by a four-stage Chebyshev impedance transformer.

The utility model discloses in, each section of antenna element is interconnect structure, and simple structure is compact, does benefit to extensive arrangement.

The utility model discloses in, medium filling structure and the protruding structure of pyramid type medium among the rectangular waveguide can make integration medium filling block, fill inside the waveguide through the spacing mode of physics. For assembly convenience, the square coaxial line and the ridge adapting section are both air, and are not actually filled with a dielectric material as the filling dielectric material.

The utility model discloses in, metal floor is used for reflecting the electromagnetic wave, reduces the backward radiation, avoids the influence each other of rear end electron device and front end array antenna.

The utility model provides an opening waveguide array can not appear the scanning blind spot in whole anticipated operating frequency to the realization surpasss 65 perfect scanning impedance matching. TE of the entire desired operating band slave waveguide unit₁₀Cut-off frequency to the frequency at which the array grating lobes appear. The structure of the antenna including the feed network is adjusted and optimized integrally through electromagnetic simulation software, and the final array can achieve 40% of working bandwidth and scan on the main plane at +/-65 degrees. By means of the surface modulation structure, the array achieves excellent wide-band wide-angle scanning performance, and is compact in structure and high in reliability.

Drawings

Fig. 1 is an oblique view of the structure of an open waveguide antenna unit.

Fig. 2 is a broadside side view of an open waveguide antenna element structure.

Fig. 3 is a side view of a narrow side of an open waveguide antenna element structure.

Fig. 4 is a structural view of a dielectric filling block.

FIG. 5 is a schematic view of an 11 × 11 array structure.

FIG. 6 is a standing wave pattern for the E-plane under periodic boundary conditions.

Fig. 7 is a standing wave pattern of the H-plane under periodic boundary conditions.

Fig. 8 is a 10GHz scanning pattern for the E-plane of the 11 x 11 array.

Fig. 9 is a 10GHz scanning pattern of the 11 x 11 array H-plane.

Reference numbers in the figures: the transformer comprises a round coaxial line 1, a round coaxial line inner conductor 2, a square coaxial line 3, a square coaxial line inner conductor 4, a ridge adapting section 5, a four-step Chebyshev converter 6, a waveguide inner medium filling block 7, a wide-edge tapered metal side wall 8, a narrow-edge tapered metal side wall 9, a pyramid-shaped medium convex structure 10, a waveguide narrow-edge side wall 11, a matching groove 12, a metal floor 13 and a waveguide wide-edge side wall 14.

Detailed Description

Fig. 1 shows a block diagram of a unit of an open waveguide array antenna. The antenna is composed of two materials, the outer wall of the waveguide, the inner conductor 2 of the round coaxial line, the inner conductor 4 of the square coaxial line, the ridge adapting section 5 and the four-step Chebyshev converter 6 are all metal structures, and the medium filling block 7 in the waveguide and the pyramid-shaped medium protruding structure 10 are made of polytetrafluoroethylene materials with the dielectric constant of 2.2. And the metal structure and the medium structure are processed by a numerical control machine. In practical use, each antenna unit is excited by the SMP coaxial connector, electromagnetic energy is converted into a TE mode in the rectangular waveguide through the round coaxial line 1, the square coaxial line 3, the ridge adapting section 5 and the four-order Chebyshev converter 6 in sequence, and the TE mode radiates outwards through the waveguide port. The excitation phase of each waveguide element can be adjusted at the input so that the array as a whole can achieve beam scanning.

Because the array is arranged in a regular triangular grid, the

triangular metal parts

8 and 9 are difficult to be integrally processed and molded with the waveguide array. In a desired working frequency band of 8 GHz to 12 GHz, the thickness of the narrow side wall of the waveguide is only about 0.6 mm to 1 mm, and the height of the conical

metal side walls

8 and 9 is consistent with that of the pyramid-shaped dielectric convex structure 10 and is about 14 mm. The whole array is processed in a manner of processing in blocks and splicing and molding. The processing parts mainly comprise a metal floor 13, an integrated internal metal block (comprising a square coaxial line inner conductor 4, a ridge adapting section 5 and a four-step Chebyshev converter 6), an integrated medium filling block (comprising a waveguide inner medium filling block 7 and a pyramid type medium protruding structure 10), a waveguide narrow side wall metal sheet (comprising a narrow side tapered metal side wall 9 and a waveguide narrow side wall 11) and a waveguide wide side wall metal sheet 14.

As shown in fig. 2 and 3, two triangular metal sidewalls 8 are included on the broad side of the waveguide and one triangular metal sidewall 9 is included on the narrow side of the waveguide. The narrow-side tapered metal side wall 9 and the waveguide narrow-side wall 11 shown in fig. 3 are integrally processed metal sheet structures, and the waveguide wide-side wall metal sheet 14 shown in fig. 5 is an entire row of sheet metal structures. The narrow-side metal sheet structures (9 and 11) are limited among the multiple rows of wide-side wall metal sheets 14 through grooves, and the wide-side wall metal sheets 14 are fixed on the metal floor 13 through screws.

The integrated dielectric filling block shown in fig. 4 comprises a waveguide inner dielectric filling block 7 and a pyramid-shaped dielectric convex structure 10, and a matching groove 12 is formed in the bottom of the integrated dielectric filling block and used for matching with the four-step chebyshev converter 6. For convenient processing, the matching groove 12 and the four-step chebyshev converter 6 are chamfered.

Fig. 1 shows an integrated inner metal block comprising a square coaxial line inner conductor 4, a ridge adapting section 5, and a four-step chebyshev transformer 6. After the integrated internal metal block and the integrated medium filling block are assembled together, the integrated internal metal block and the integrated medium filling block are physically limited in the waveguide.

Fig. 6 is a standing wave diagram of the E-plane under the periodic boundary condition, and it can be known that the standing wave of the antenna is less than 2.3 in the 65 ° scanning range of the E-plane in the whole operating frequency band (8 GHz to 12 GHz).

Fig. 7 is a standing wave diagram of the H-plane under the periodic boundary condition, and it can be known that the standing wave of the antenna is less than 2.0 in the 65 ° H-plane scanning range of the whole operating frequency band (8 GHz to 12 GHz).

Fig. 8 and 9 are beam scanning patterns of the 11 x 11 array at center frequency 10GHz for the E-plane and H-plane, respectively, showing that the array can scan up to 65 °.

Claims

1. A broadband wide-angle scanning open waveguide phased array antenna is characterized in that an M multiplied by N two-dimensional array is formed by arranging a plurality of rectangular open waveguide antenna units in a regular triangular grid mode; the basic shape of the antenna unit is a rectangular cylinder, which is composed of three sections, and the antenna unit sequentially comprises the following components from top to bottom: the surface modulation structure, the rectangular waveguide with fast medium filling and the feed network are adopted; the antenna unit is excited and fed at the bottom through a coaxial connector, and the bottom of the array is fixed by a metal floor;

the array is arranged in a regular triangle grid manner, and the meaning is that in the array, in the same row direction, antenna units are sequentially extended and arranged; the central axes of the adjacent three antenna units are distributed in a regular triangle between the two adjacent rows, and the positions of the antenna units in the two rows are flush;

the rectangular opening waveguide antenna unit is a single-wire polarization working antenna, and the main mode is TE₁₀Mode(s).

2. The broadband wide angle scanning aperture waveguide phased array antenna of claim 1, wherein the surface modulation structure comprises a pyramid-type dielectric bump structure and triangular metal sidewalls; here, the pyramid-shaped dielectric protrusion structure is a quadrangular pyramid, and the bottom of the quadrangular pyramid is a rectangle matched with the rectangular waveguide; the metal side wall on one side of the wide side of the quadrangular pyramid is two isosceles triangles which are in the same structure and are arranged in parallel, and the metal side wall on one side of the narrow side of the quadrangular pyramid is one isosceles triangle;

the height of the pyramid-shaped dielectric convex structure is the same as that of the triangular metal side wall, and the pyramid-shaped dielectric convex structure is half wavelength of the central frequency.

3. The wideband wide angle scanning aperture waveguide phased array antenna of claim 2, wherein the feed network comprises three sections, a coaxial input section, a mode conversion section, and an impedance transformation section; the coaxial input section is realized by a standard SMP coaxial connector; the mode conversion section comprises a round coaxial line inner conductor, a square coaxial line inner conductor and a ridge adaptation section and is used for realizing the conversion from a TEM mode in the round coaxial line to a TEM mode in the square coaxial line and further realizing the conversion to TE through the ridge adaptation section₁₀Smooth transition of the mode; the impedance matching section is realized by a four-stage Chebyshev impedance transformer.

4. The broadband wide-angle scanning open waveguide phased array antenna according to claim 3, wherein the dielectric filling structure and the pyramid-shaped dielectric protrusion structure in the rectangular waveguide are made into an integrated dielectric filling block and filled in the waveguide in a physical limiting manner; the square coaxial line and the ridge adapting section are both air.