CN109818158B - Broadband SIW back-cavity slot antenna array adopting L-shaped slot units - Google Patents

Abstract

The invention discloses a broadband substrate integrated waveguide (SIW) cavity-backed slot antenna array using an L-shaped slot unit, comprising a parallel-fed power division network and several SIW cavity-backed slot antenna units. The antenna unit is mainly composed of The SIW rectangular resonator is composed of two pairs of L-shaped slot pairs that are rotationally symmetrical with respect to the center of the resonator cavity, and the two L-shaped slots of the L-shaped slot pair are placed face to face. By designing the positions of metallized through holes and metallized blind holes, each antenna unit forms a rectangular SIW isolation cavity with one long side open in the dielectric adhesive layer, which significantly reduces the electromagnetic field leaked in the adhesive layer to the direction of the antenna array. Figure and gain effects. The antenna array realized by the invention has the characteristics of wide pattern bandwidth, flat in-band gain, narrow beams on both azimuth and elevation planes, and low cross-polarization level.

Description

A Broadband SIW Cavity-Backed Slot Antenna Array Using L-shaped Slot Elements

technical field

The invention relates to a broadband cavity-backed slot antenna array based on a substrate integrated waveguide (Substrate Integrated Waveguide, SIW) technology and adopts a novel L-shaped slot unit, and belongs to the field of antenna technology.

Background technique

With the increasing demand for driving safety and autonomous driving, the application prospect of millimeter-wave vehicle radar is very broad. Antenna array is the key component of millimeter-wave vehicle-mounted radar system, and its performance directly affects the detection distance, detection angle, anti-interference ability and resolution of the radar system.

In recent years, the industry's research on millimeter-wave vehicle radar has become more and more in-depth, and the antenna array of its radar system has also begun to develop in the direction of multi-function, broadband, and high gain. However, because the millimeter-wave vehicle radar system is relatively strict in various indicators of its antenna array, and is limited by factors such as processing accuracy, many methods to improve antenna performance are not practical. Therefore, millimeter-wave vehicle radar has a large demand for antenna arrays that are easy to plane integration, wideband, narrow beam, and low cross-polarization level.

SUMMARY OF THE INVENTION

Purpose of the invention: Aiming at the problems and deficiencies in the existing 79GHz millimeter-wave vehicle-mounted radar antenna technology, the present invention adopts the substrate integrated waveguide technology to provide a broadband antenna array that can cover the entire 76-81GHz millimeter-wave vehicle-mounted radar frequency band. The antenna array has the advantages of wideband, flat in-band gain, and low cross-polarization level.

Technical scheme: In order to realize the above-mentioned purpose of the invention, the present invention adopts the following technical scheme:

A broadband SIW cavity-backed slot antenna array using an L-shaped slot unit, including a parallel-fed power division network and a plurality of SIW cavity-backed slot antenna units; the SIW cavity-backed slot antenna unit is composed of upper and lower dielectric substrates through an adhesive layer. It is formed by bonding, including the upper SIW cavity-backed slot radiation layer and the lower SIW feed layer; the L-shaped slot is arranged on the upper surface of the upper dielectric substrate where the SIW resonant cavity is located, and the antenna unit is arranged on the upper surface of the lower dielectric substrate through the The SIW cavity-backed slot antenna unit is provided with two pairs of L-shaped slot pairs that are rotationally symmetric with respect to the center of the SIW resonant cavity. There are blind vias nearby for improved impedance matching.

In a preferred embodiment, the SIW resonator operates in the TE ₂₁₀ mode, the two sides of the center of the SIW resonator will get equal-amplitude and opposite electric fields, and the electric fields on the two excited L-shaped slot pairs are equal in magnitude and in phase.

In a preferred embodiment, the antenna array is provided with metallized vias penetrating from the top copper layer to the bottom copper layer, and the metallized vias not only constitute part of the SIW feeding structure of the lower layer, but also form part of the SIW feed structure of the lower layer. A rectangular SIW isolation cavity with one long side open is formed in it.

In a preferred embodiment, when the antenna array is arrayed in the y-direction, the same column of elements in the x-direction of the antenna is 180° rotationally symmetric about the center of the array, wherein the y-direction is the length direction of the L-shaped slot, and the x-direction is the L-shaped slot width. direction.

In a preferred embodiment, the antenna array is a 2×4 antenna array, and 8 SIW cavity-backed slot antenna units are fed through a parallel-fed one-to-eight power division network.

Beneficial effects: Compared with the existing 79GHz millimeter wave vehicle radar antenna array, the present invention has the following advantages:

1) The full-parallel feed method is adopted, so that the antenna array can have stable pattern characteristics in the wide frequency band of 75-82GHz, and the in-band gain fluctuation is less than 1dB, covering the entire 76-81GHz millimeter-wave vehicle radar frequency band.

2) For the multi-layer slot-coupled feeding array antenna located in the millimeter-wave frequency band, by cleverly designing the positions of metallized vias and blind holes, a rectangular SIW isolation cavity with one long side open on one side is formed in the dielectric adhesive layer. The influence of the electromagnetic field leaked in the adhesive layer on the antenna array pattern and gain is significantly reduced.

3) The L-shaped slot pair of the antenna unit is placed in a rotationally symmetrical manner, and is placed in a mirror-symmetrical manner about the center of the array when forming an array, which can offset the electric field in the cross-polarization direction at the corner of the L-shaped slot and obtain a lower cross-polarization level.

4) The antenna array is a plane structure, which is easy to be integrated on the circuit board.

Description of drawings

Fig. 1 is the overall structure model diagram of the antenna array in the present invention;

2 is a side view of an antenna array in the present invention;

3 is a model diagram of the upper dielectric substrate of the antenna array in the present invention;

4 is a model diagram of an antenna array adhesive layer in the present invention;

FIG. 5 is a model diagram of the lower dielectric substrate of the antenna array in the present invention;

In Figure 1-5: 1-L-shaped slot 1; 2-matching blind hole; 3-SIW resonant cavity; 4-feed point; 5-metal ground; 6-SIW transfer WR10 test structure; 7-metallized through hole; 8-metallized blind hole; 9-adhesive layer; 10-upper dielectric substrate; 11-lower dielectric substrate 11; 12-parallel-fed one-to-eight power division network;

Fig. 6 is the result diagram of antenna array simulation and test standing wave parameter in the present invention;

Fig. 7 is the result diagram of antenna array simulation and test gain in the present invention;

FIG. 8 is an E-plane simulation and test pattern of the antenna array at 76 GHz in the present invention;

Fig. 9 is the H-plane simulation and test pattern of the antenna array at 76GHz in the present invention;

FIG. 10 is an E-plane simulation and test pattern of the antenna array at 79GHz in the present invention;

11 is the H-plane simulation and test pattern of the antenna array at 79GHz in the present invention;

Fig. 12 is the E-plane simulation and test pattern of the antenna array at 81GHz in the present invention;

FIG. 13 is an H-plane simulation and test pattern of the antenna array at 81 GHz in the present invention.

Detailed ways

Below in conjunction with specific embodiments, the present invention will be further illustrated, and it should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The modifications all fall within the scope defined by the appended claims of this application.

The embodiment of the present invention discloses a broadband substrate integrated waveguide cavity-backed slot antenna array using L-shaped slot units, which mainly includes several SIW cavity-backed slot antenna units and a parallel-feed power division network. The end of the power division network is connected to the SIW switch. Connect to the WR10 test structure. The SIW cavity-backed slot antenna unit is a double-layer structure, including the upper SIW cavity-backed slot radiating layer and the lower SIW feeding layer; the L-shaped slot is arranged on the upper surface of the upper dielectric substrate where the SIW resonator is located, and the antenna unit is arranged on the lower SIW through the The coupling slot on the surface is fed, and the antenna can be processed by a printed circuit board (Printed Circuit Board, PCB) process. Specifically, in the embodiment of the present invention, the detailed structural design and test results of the present invention are described in detail by using a 2×4 antenna array structure.

As shown in Figure 1, the SIW cavity-backed slot antenna array has 4 array elements in the x direction and 2 array elements in the y direction, a total of 8 array elements. The structural model of the SIW cavity-backed slot antenna array mainly includes: L-shaped slot 1 and matching blind hole 2 on SIW resonant cavity 3; feed point 4; metal ground 5; SIW transfer WR10 test structure 6; metallized through hole 7; metallized blind hole 8; adhesive layer 9; The upper layer dielectric substrate 10 ; the lower layer dielectric substrate 11 ;

The SIW cavity-backed slot antenna unit is composed of two layers of Rogers RO3003 sheets with a thickness of h ₁ =h ₃ =0.508mm, and the upper and lower dielectric substrates are bonded together by an adhesive layer of Rogers 4450B, the thickness of which is h ₂ =0.09 mm. The lower dielectric substrate 11 of the antenna unit is a feeding layer, which feeds the radiating structure of the upper antenna through a transverse slot opened on the upper surface of the copper layer. The upper dielectric substrate 10 is the SIW cavity-backed slot radiation layer, and the left half of the SIW resonator 3 is a pair of L-shaped slots 1 placed face to face. Two pairs of rotationally symmetric L-shaped slot pairs were obtained. In order to feed the two L-shaped slot pairs at the same time, the length and width of the SIW resonator 3 should be reasonably optimized to make it work in the TE ₂₁₀ mode, so that the left and right sides of the center of the SIW cavity 3 will get equal amplitude and opposite Electric field, the electric fields on the two excited L-shaped slit pairs are equal in amplitude and in phase, forming an edge-emitting pattern.

By optimizing and matching the position parameters X _m and Y _m of the blind hole 2 , the impedance matching of the antenna unit can be improved, and at the same time, the in-phase excitation of the four L-shaped slots can be ensured. At the same time, a small longitudinal slot is introduced at one end of each transverse slot. By adjusting the length t of the longitudinal slot, the impedance matching of the antenna unit can be significantly improved.

3 to 5 are schematic diagrams of the structure model of each layer of the antenna array, wherein the length of the L-shaped slot 1 is L _s1 and the width is W _s1 ; the length of the SIW resonant cavity 3 is L _c and the width is W _c ; The radius of the hole 7 and the metallized blind hole 8 is d, and the distance between the holes is p; the length of the upper dielectric substrate 10 is L _up and the width is W _up ; the distance between the antenna elements in the x direction is D _ex , and the distance in the y direction is D ex . is _{Dey; the length of the SIW isolation cavity formed by the metallized through hole 7 in the adhesive layer 9 is Lisc ;} the length of the coupling slot is L _s2 , the width is W _s2 , and the distance from the short-circuit end is D _s2 ; SIW right-angle corner matching hole The distances from the right angle in the x and y directions are D _vx and D _vy respectively; D _m1 and D _m2 are the distances between the matching hole and the sidewall of the SIW; d ₂ is the diameter of the center matching metallized blind hole; L _d and W _d are the length and width of the underlying dielectric substrate 11, respectively.

By punching the metallized through holes 7 near the metallized blind holes 8 used to form the SIW resonant cavity 3 to form two “king”-shaped metallized through-hole arrays, the electromagnetic leakage from the adhesive layer 9 can be significantly reduced The effect of energy on the pattern of an antenna array. It can be seen from FIG. 3 to FIG. 5 that the metallized through hole 7 penetrates from the top copper layer to the bottom copper layer without destroying the SIW structure of the upper and lower layers, which not only constitutes the parallel-fed type of the lower dielectric substrate 11 1/8. The power division network 12 also forms eight rectangular SIW isolation cavities with one long side open in the adhesive layer 9. Due to the existence of the equivalent electric wall, the coupling gap of a unit in the array leaks through the adhesive layer 9. The energy will be completely isolated from the coupling gap of the surrounding units, and the leaked electromagnetic energy will be transmitted in opposite directions, so that the leaked electromagnetic energy will cancel each other in the y direction and will not affect the gain and far-field direction of the antenna array. graph properties. In addition, when the antenna array is arrayed in the y-direction, a column of elements in the x-direction of the antenna is replicated 180° rotationally symmetrically about the center of the array, which can cancel the electric field in the y-direction at the corner of the L-shaped slot and reduce the cross-polarization level. .

The antenna size is optimized by electromagnetic simulation software, and the antenna size parameters are shown in Tables 1 to 4. The meaning of each parameter has been explained above.

Antenna parameter values corresponding to the model in Table 1 and Fig. 2

parameter Value (mm) parameter Value (mm) h₁ 0.508 h₃ 0.508 h₂ 0.09

Antenna parameter values corresponding to the model in Table 2 and Fig. 3

parameter Value (mm) parameter Value (mm) L_s1 1.65 D_ex 5.5 W_s1 0.25 D_ey 3.15 t 0.245 d 0.3 X_m 0.17 p 0.5 Y_m 0.34 L_up 24.18 L_c 4.59 W_up 8.25 W_c 2.15

Table 3 Antenna parameter values corresponding to the model in Fig. 4

parameter Value (mm) parameter Value (mm) L_up 24.18 L_isc 5.5 W_up 8.25

The corresponding antenna parameter values in the model shown in Table 4 and Fig. 5

parameter Value (mm) parameter Value (mm) L_s2 1.18 D_vy 0.6 W_s2 0.28 D_m2 0.53 D_s2 1.33 d₂ 0.4 D_m1 0.65 L_d 48.77 D_vx 0.6 W_d 40

The test results are shown in Figure 6 to Figure 13. Fig. 6 is the simulation and test standing wave parameters of the antenna array in the present invention; Fig. 7 is the simulation and test gain of the antenna array in the present invention; Fig. 8 is the E-plane simulation and test pattern of the antenna array in the present invention at 76GHz; Fig. 9 It is the H-plane simulation and test pattern of the antenna array in the present invention at 76GHz; Figure 10 is the E-plane simulation and test pattern of the antenna array in the present invention at 79GHz; Figure 11 is the H-plane simulation of the antenna array in the present invention at 79GHz and test pattern; Figure 12 is an E-plane simulation and test pattern of the antenna array at 81GHz in the present invention; Figure 13 is an H-plane simulation and test pattern of the antenna array at 81GHz in the present invention. It can be seen from the measured results that the designed broadband SIW cavity-backed slot antenna array achieves a -10dB impedance bandwidth of 75-82GHz, and achieves a gain of 16dBi and a cross-polarization level of -30.3dB at the center frequency of 79GHz.

Claims (4)

1. a broadband SIW cavity-backed slot antenna array that adopts L-shaped slot unit, it is characterized in that: comprise and feed type power division network and some SIW cavity-backed slot antenna units; Described SIW cavity-backed slot antenna unit is composed of upper and lower layers. The dielectric substrate is formed by bonding the adhesive layer, including the upper SIW cavity back cavity slot radiation layer and the lower SIW feeding layer; the L-shaped slot is set on the upper surface of the upper dielectric substrate where the SIW resonant cavity is located, and the antenna unit is arranged on the The coupling slot on the upper surface of the lower dielectric substrate is fed; the SIW cavity-backed slot antenna unit is provided with two pairs of L-shaped slot pairs that are rotationally symmetrical relative to the center of the SIW resonant cavity, and the two L-shaped slot pairs of the L-shaped slot pair are placed face to face, each For the L-shaped slot, there are blind holes near the slot for improving impedance matching; the antenna array is provided with metallized vias penetrating from the top copper layer to the bottom copper layer, and the metallized vias both constitute part of the lower layer. In the SIW feeding structure, a rectangular SIW isolation cavity with one long side open on one side is formed in the adhesive layer. 2. The broadband SIW cavity-backed slot antenna array using L-shaped slot unit according to claim 1, it is characterized in that: SIW resonator works in TE ₂₁₀ mode, and both sides of the center of SIW resonator can obtain equal-amplitude opposite Electric field, the electric field on the excited two pairs of L-shaped slits is equal in magnitude and in phase. 3. The broadband SIW cavity-backed slot antenna array using L-shaped slot unit according to claim 1, it is characterized in that: when the antenna array is arrayed in the y direction, the same row unit in the x direction of the antenna is rotated about the center of the array by 180° Symmetric replication, where the y direction is the length direction of the L-shaped slit, and the x direction is the width direction of the L-shaped slit. 4. The broadband SIW cavity-backed slot antenna array adopting L-shaped slot unit according to claim 1, is characterized in that: the antenna array is a 2×4 antenna array, and 8 SIW cavity-backed slot antenna units are divided by parallel feeding It is fed by an octagonal network.

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