A broadband waveguide slot array antenna

Abstract

The application discloses a broadband waveguide slot array antenna, which comprises a first metal plate, a second metal plate, a third metal plate and a fourth metal plate which are stacked in sequence, and a radiation port is formed on the first metal plate and the second metal plate; the radiation port longitudinally penetrates the first metal plate and the second metal plate and is in a wide-side symmetrical oblique slot structure; a pair of radiation waveguides and a pair of coupling longitudinal slots which are in communication with each other are formed by longitudinally slotting the middle part of the third metal plate; a coupling waveguide and a waveguide matching structure which are in communication with each other are formed by longitudinally slotting the middle part of the fourth metal plate; the radiation port, the radiation waveguide, the coupling longitudinal slot, the coupling waveguide and the waveguide matching structure are in communication with each other in sequence, and a radiation channel is formed. Through the structure, the coupling between antennas can be reduced, the isolation and the antenna gain are improved, the antenna bandwidth is effectively widened, the influence of the processing error of the radiation slot and the contact slot between the metal plates on the antenna radiation is reduced, and the antenna is easy to process and install.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waveguide slot antenna, and particularly relates to a wideband waveguide slot array antenna. BACKGROUND

[0002] The waveguide slot antenna refers to a kind of aperture antenna with a slot on the wall of waveguide pipe or cavity resonator, and electromagnetic wave is radiated to the outside space through the slot. It is light in weight, simple in processing, easy to realize low sidelobe, and can meet the engineering requirements of high reliability, and is widely used in the field of radar. At present, the waveguide slot antenna is mostly realized by opening a slot on the standard rectangular metal waveguide or ridge metal waveguide.

[0003] In radar wireless communication, the radar communication frequency is higher, and the channel capacity is larger, so the working frequency of the antenna is higher, the bandwidth is wider, the size of the antenna becomes smaller, the structure is more complex, and the processing requirement of the antenna is higher. At present, the radiation slot of the slot antenna is mostly in the form of thin single-layer waveguide pipe, and the processing precision requirement is relatively high. When the processing error deviation is large or there is a gap between the plates during installation, the characteristics of the antenna will be greatly affected. The reason is that the rectangular waveguide used in the radiation waveguide is a four-sided closed metal structure, and the metal plates are fixed by screws during installation. Thus, there will inevitably be a gap between the plates, and the size of the gap will greatly affect the performance of the rectangular waveguide. SUMMARY

[0004] In view of the above defects of the prior art, the purpose of the present application is to provide a waveguide slot antenna structure, which can reduce the influence of the radiation slot processing error and the contact gap between the metal plates on the performance of the antenna.

[0005] To achieve the above-mentioned purpose, the present application provides a wideband waveguide slot array antenna, which comprises a first metal plate, a second metal plate, a third metal plate and a fourth metal plate stacked in sequence, a radiation port longitudinally passing through the first metal plate and the second metal plate is formed by longitudinally slotting the middle part of the first metal plate and the second metal plate; a pair of radiation waveguides and a pair of coupling longitudinal slots in communication with each other are formed by longitudinally slotting the middle part of the third metal plate; a coupling waveguide and a waveguide matching structure in communication with each other are formed by longitudinally slotting the middle part of the fourth metal plate; the radiation port, the radiation waveguide, the coupling longitudinal slot, the coupling waveguide and the waveguide matching structure are in communication with each other in sequence, forming a radiation channel; the length direction of the radiation waveguide is perpendicular to the length direction of the coupling waveguide.

[0006] Further, the radiation port adopts a wide-side symmetrical slanting slot structure, which comprises a wide-side radiation longitudinal slot formed by longitudinally slotting the middle part of the first metal plate, and a first wide-side slanting longitudinal slot and a second wide-side slanting longitudinal slot which are in communication with each other and are formed by longitudinally slotting the middle part of the second metal plate; the wide-side radiation longitudinal slot comprises 2*N slots arranged in an array, the first wide-side slanting longitudinal slot and the second wide-side slanting longitudinal slot each comprise 2*N slots, and the 2*N slots of the wide-side radiation longitudinal slot and the 2*N slots of the first wide-side slanting longitudinal slot and the second wide-side slanting longitudinal slot are combined one by one to form 2*N longitudinal radiation slots, and the centers of the three layers of slots of the longitudinal radiation slots are on a straight line; the center line spacing between the two rows of slots is 1 / 2λ, and the center spacing between the N slots of each row is 1 / 2λ, wherein λ is the wavelength of the waveguide radiation.

[0007] Further, the length and width of the slots of the first wide-side slanting longitudinal slot are slightly greater than the length and width of the slots of the wide-side radiation longitudinal slot and the second wide-side slanting longitudinal slot.

[0008] Further, the radiation waveguide is a groove gap ridge waveguide, and metal ridges are formed on the two short sides of the groove gap ridge waveguide, and the height of the metal ridges is lower than the depth of the cavity of the groove gap ridge waveguide.

[0009] Further, a plurality of metal pins arranged in an array are formed on the upper surface of the third metal plate outside the radiation waveguide.

[0010] Further, the coupling longitudinal slot is a slanting longitudinal slot, and the length direction of the slot of the coupling longitudinal slot and the length direction of the radiation waveguide form a certain inclination angle.

[0011] Further, the coupling waveguide is a groove gap waveguide, and the length direction of the coupling waveguide is perpendicular to the length direction of the radiation waveguide, and the width of the coupling waveguide is adapted to the coupling longitudinal slot, and the longitudinal projection of the coupling longitudinal slot falls within the coupling waveguide.

[0012] Further, a plurality of metal pins arranged in an array are formed on the upper surface of the fourth metal plate outside the coupling waveguide.

[0013] Further, the waveguide matching structure is composed of three layers of rectangular waveguides, and the inner layer waveguide is in communication with the coupling waveguide; the three layers of rectangular waveguides of the waveguide matching structure are in a structure of gradually reducing from outside to inside.

[0014] Further, a first installation gap is arranged between the second metal plate and the third metal plate, and a second installation gap is arranged between the third metal plate and the fourth metal plate, and the gap range of the first installation gap and the second installation gap is 0-0.05mm.

[0015] The present application has the following beneficial effects:

[0016] (1) Compared with the traditional waveguide radiation slot antenna, the antenna of the application reduces the radiation slot processing error and the influence of the metal plate contact slot on the antenna radiation, is easy to process and install, has good popularization value and application prospect;

[0017] (2) The radiation waveguide and the coupling waveguide adopt the slot gap waveguide structure, which can reduce the coupling between antennas, improve the isolation and the antenna gain;

[0018] (3) The multi-layer matching structure can effectively expand the antenna bandwidth. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structure development view of an embodiment of the wideband waveguide slot array antenna of the application;

[0020] Figure 2 is an antenna section view;

[0021] Figure 3 is an antenna local enlarged view;

[0022] Figure 4 is an L1 layer top view of the antenna;

[0023] Figure 5 is an L2 layer top view of the antenna;

[0024] Figure 6 is an L3 layer top view of the antenna;

[0025] Figure 7 is an L4 layer top view of the antenna;

[0026] Figure 8 is an antenna radiation pattern of an antenna sample;

[0027] Figure 9 is an antenna matching impedance diagram of an antenna sample;

[0028] Figure 10 is a frequency-standing wave ratio diagram obtained by modeling simulation of an antenna sample.

[0029] Wherein: L1 is a first metal plate; L2 is a second metal plate; L3 is a third metal plate; L4 is a fourth metal plate; 11 is a wide edge radiation longitudinal slot; 12 is a first wide edge inclined longitudinal slot; 13 is a second wide edge inclined longitudinal slot; 2 is a radiation waveguide; 21 is a metal ridge; 3 is a coupling waveguide; 4 is a coupling longitudinal slot; 5 is a waveguide matching structure; 61 is a first installation gap; 62 is a second installation gap; 7 is a first pin array; 8 is a second pin array. DETAILED DESCRIPTION

[0030] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0031] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, this invention provides an embodiment of a broadband waveguide slot antenna. The broadband waveguide slot antenna includes a first metal plate L1, a second metal plate L2, a third metal plate L3, and a fourth metal plate L4 stacked sequentially.

[0033] A longitudinal slot is formed in the first metal plate L1 and the second metal plate L2 to create a radiation port 1. The radiation port 1 extends longitudinally through the first metal plate L1 and the second metal plate L2, and has a wide-sided symmetrical oblique slit structure. The radiation port 1 is used to transmit or receive signals.

[0034] The specific structure of the radiation port 1 includes: a wide-sided radiating longitudinal slit 11 formed by longitudinally slotting a first metal plate L1, and two levels of wide-sided inclined longitudinal slits formed by longitudinally slotting a second metal plate L2: a first wide-sided inclined longitudinal slit 12 opening on the upper surface and a second wide-sided inclined longitudinal slit 13 opening on the lower surface. In this embodiment, the wide-sided radiating longitudinal slit 11 includes 2*N slits arranged in an array, and the first wide-sided inclined longitudinal slit 12 and the second wide-sided inclined longitudinal slit 13 each include 2*N slits, which are combined one-to-one with the 2*N slits of the wide-sided radiating longitudinal slit 11 to form 2*N longitudinal radiating slits. The centers of the three layers of slits in the longitudinal radiating slits are on a straight line. In the wide-sided radiating longitudinal slit 11, the center-line distance between two rows of slits is 1 / 2λ, and the center-line distance between the N slits in each row is 1 / 2λ, where λ is the waveguide radiation wavelength. The length and width of the first wide-side inclined longitudinal slit 12 are slightly larger than the length and width of the wide-side radial longitudinal slit 11 and the second wide-side inclined longitudinal slit 13, thus confining the radiated energy within the wide-side radial longitudinal slit 11. The current distribution of the power supply can be adjusted by changing the inclination angle of the first wide-side inclined longitudinal slit 12 and the second wide-side inclined longitudinal slit 13.

[0035] The third metal plate L3 has a pair of radiating waveguides 2 and a pair of coupling longitudinal slots 4 formed by slotting in the middle part of the third metal plate L3. Preferably, the radiating waveguides 2 adopt a slot-gap ridge waveguide structure, and a pair of metal ridges 21 of the slot-gap ridge waveguide are arranged on the short sides of the cavity of the radiating waveguide 2, and the height of the metal ridges 21 is lower than the depth of the cavity of the slot-gap ridge waveguide. The pair of radiating waveguides 2 correspond to a pair of second wide-side inclined longitudinal slots 13 in the radiation port 1. By adjusting the length, width and height of the metal ridges of the slot-gap ridge waveguide and the radiating slot, the resonant frequency can be changed. On the outside of the radiating waveguides 2, a plurality of rectangular metal pins arranged in an array are formed on the upper surface of the third metal plate L3, which are defined as a first pin array 7. The main function of the first pin array 7 is to suppress electromagnetic signals outside the working frequency band, enhance the radiation performance, reduce the coupling between antenna elements, and improve the isolation. In the embodiment, the length, width and height of the metal pins in the second pin array 8 are 0.5mm*0.5mm*0.6mm, and by adjusting the size and spacing of the metal pins in the second pin array 8, the range of the working frequency can be adjusted. The upper surface of the metal pins is 0.02mm lower than the upper surface of the metal plate L3. The coupling longitudinal slots 4 are inclined longitudinal slots, and a pair of coupling longitudinal slots 4 respectively communicate with the waveguide cavities of a pair of radiating waveguides 2 and form a certain inclination angle with the length direction of the radiating waveguides 2, which are used for impedance matching and energy coupling. As for the position relationship between each radiating waveguide 2 and the coupling longitudinal slot 4 in the horizontal direction, those skilled in the art should know that the centers of the two are coincident.

[0036] The fourth metal plate L4 is provided with a coupling waveguide 3 and a waveguide matching structure 5 formed by slotting the middle part of the fourth metal plate L4. In the embodiment, the coupling waveguide 3 is a slot gap waveguide structure, the length direction of which is perpendicular to the length direction of the radiating waveguide 2, and the width of which is adapted to the coupling longitudinal slot 4. After assembly, the coupling longitudinal slot 4 and the coupling waveguide 3 are in cavity communication. The resonant frequency can be changed by adjusting the length and width of the cavity of the coupling waveguide 3. On the upper surface of the fourth metal plate L4, a plurality of rectangular metal pins arranged in an array are formed outside the coupling waveguide 3, which are defined as a second pin array 8. The second pin array 8 and the first pin array 7 are processed in the same way and have the same function, which are used to suppress electromagnetic signals outside the working frequency band, enhance the radiation performance, reduce the coupling between antenna elements, and improve the isolation. In the embodiment, the length, width and height of the metal pins in the second pin array 8 are 0.5mm*0.5mm*0.6mm. By adjusting the size and spacing of the metal pins in the second pin array 8, the working frequency range can be adjusted. Generally, the first pin array 7 and the second pin array 8 can use metal pins of the same size and the same array spacing. The waveguide matching structure 5 is composed of three layers of rectangular waveguides, which are used for impedance matching and signal transmission. Generally, the length and width of the cross section of the three layers of rectangular waveguides decrease from the outside to the inside. As for the horizontal position relationship between the coupling waveguide 3 and the waveguide matching structure 5, those skilled in the art should know that the centers of the two are coincident.

[0037] In the structure, the fourth metal plate L4 is the bottom plate, and its thickness is greater than those of the other three metal plates, and the first metal plate L1 is the thinnest.

[0038] In the antenna, the slot current distribution of the coupling longitudinal slot 4 and the radiating port 1 can be selected according to the actual antenna requirements.

[0039] In assembly, the four plates are fixed by bolts. A first installation gap 61 can be left between the second metal plate L2 and the third metal plate L3 during processing, and a second installation gap 62 can be left between the third metal plate L3 and the fourth metal plate L4 during processing, as shown in Figure 3 The gap range of the first installation gap 61 and the second installation gap 62 can be controlled to be less than or equal to 0.05mm. In such a structure gap, the antenna performance will not be substantially affected.

[0040] Experimental results:

[0041] In the example, a three-dimensional high-frequency electromagnetic field simulation software HFSS tool is used to model and simulate according to the above antenna structure, the thickness of each metal plate, the structure size of each waveguide structure and slot, and finally the following simulation data are obtained.

[0042] From Figure 8The antenna radiation pattern shown can be seen that the antenna gain is close to 15dB, and the sidelobe is greater than 20dB.

[0043] From Figure 9 The antenna matching impedance diagram, Figure 10 The frequency-voltage standing wave ratio (VSWR) test diagram can be seen that the antenna sample has a VSWR less than 1.5 at 75.5GHz-78.5GHz, a VSWR less than 1.2 at 76.0GHz-78.0GHz, realizes a matching of 3GHz bandwidth, and meets the demand of automobile radar for wide bandwidth.

[0044] The product structure form description and simulation data can be obtained that the wideband waveguide radiating slot antenna has the following beneficial effects:

[0045] (1) Compared with the traditional waveguide radiating slot antenna, the antenna reduces the influence of the radiating slot machining error and the metal plate contact slot on the antenna radiation, is easy to process and install, has good popularization value and application prospect;

[0046] (2) The slot gap waveguide structure of the radiating waveguide and the coupling waveguide can reduce the coupling between the antennas, improve the isolation and the antenna gain;

[0047] (3) The multi-layer matching structure can effectively expand the antenna bandwidth.

[0048] Although the present application is specifically shown and introduced in combination with the preferred embodiments, it should be understood by those skilled in the art that various changes can be made in form and details without departing from the spirit and scope of the present application defined in the appended claims, and all such changes are within the protection scope of the present application.

Claims

1. A wideband waveguide slot array antenna, characterized by, The first metal plate, the second metal plate, the third metal plate and the fourth metal plate are stacked in sequence, The first metal plate and the second metal plate are longitudinally slotted in the middle part to form a radiation port longitudinally penetrating the first metal plate and the second metal plate; The radiation port adopts a wide-side symmetrical slanting slot structure, comprising a wide-side radiation longitudinal slot formed by longitudinally slotting a middle part of the first metal plate, and a first wide-side slanting longitudinal slot and a second wide-side slanting longitudinal slot in communication with each other and formed by longitudinally slotting a middle part of the second metal plate; the wide-side radiation longitudinal slot comprises 2 N slots arranged in an array, and the first wide-side slanting longitudinal slot and the second wide-side slanting longitudinal slot each comprise 2 N slots, which are combined with the 2 N slots of the wide-side radiation longitudinal slot in a one-to-one manner to form 2 N longitudinal radiation slots, and the centers of the three layers of slots of the longitudinal radiation slots are on a straight line; the center line spacing between the two rows of slots is 1 / 2λ, and the center spacing between the N slots of each row is 1 / 2λ, wherein λ is the wavelength of the waveguide radiation. The third metal plate is longitudinally slotted in the middle part to form a pair of radiation waveguides and a pair of coupling longitudinal slots in communication with each other; The radiation waveguide is a slot-gap ridge waveguide, and a metal ridge is formed on both sides of the short edge of the slot-gap ridge waveguide, and the height of the metal ridge is lower than the depth of the cavity of the slot-gap ridge waveguide; The fourth metal plate is longitudinally slotted in the middle part to form a coupling waveguide and a waveguide matching structure in communication with each other; The coupling waveguide is a slot-gap waveguide, and the length direction of the coupling waveguide is perpendicular to the length direction of the radiation waveguide, and the width of the coupling waveguide is adapted to the coupling longitudinal slot, and the longitudinal projection of the coupling longitudinal slot falls within the coupling waveguide; The waveguide matching structure is composed of three layers of rectangular waveguides, and the inner layer waveguide is in communication with the coupling waveguide; the three layers of rectangular waveguides are in a structure of gradually reducing from outside to inside; The radiation port, the radiation waveguide, the coupling longitudinal slot, the coupling waveguide and the waveguide matching structure are in communication with each other in sequence, forming a radiation channel; the length direction of the radiation waveguide is perpendicular to the length direction of the coupling waveguide; A first installation gap is arranged between the second metal plate and the third metal plate, and a second installation gap is arranged between the third metal plate and the fourth metal plate, and the gap range of the first installation gap and the second installation gap is 0-0.05mm.

2. The wide-band waveguide slot array antenna of claim 1, wherein, A plurality of metal pins are formed on the upper surface of the third metal plate outside the radiation waveguide in an array distribution.

3. The wide-band waveguide slot array antenna of claim 1, wherein, The coupling longitudinal slot is an inclined longitudinal slot, and a certain inclination is formed with the length direction of the radiation waveguide.

4. The wide-band waveguide slot array antenna of claim 1, wherein, A plurality of metal pins are formed on the upper surface of the fourth metal plate outside the coupling waveguide in an array distribution.

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