CN113851850B - Zero-crossing scanning leaky-wave antenna - Google Patents

Abstract

The invention discloses a zero-point scanning leaky-wave antenna, belonging to the technical field of microwave antenna design, comprising: etching periodic slots on the metal on the upper layer of a substrate integrated waveguide, and exciting even-mode SSPPs to form a low-loss transmission line; Periodic sinusoidal modulation to form a leaky wave antenna; sinusoidal slots are etched on the underlying metal of the integrated waveguide on the substrate. The present invention uses sinusoidally modulated SIW‑SSPPs transmission lines to excite infinite space harmonics, in which fast waves generate leaky wave radiation, and then breaks the symmetry of the structure through the periodic sinusoidal gaps etched on the bottom of the SIW, so that the beam follows the frequency from backward to forward To scan, that is to achieve continuous scanning across the zero point. The antenna adopts the SIW structure, which has the advantages of low loss, simple structure, and easy integration with the feed structure, and the strong binding of SSPPs to electromagnetic waves further reduces the loss.

Description

A Leaky-Wave Antenna Crossing Zero Scanning

technical field

The invention belongs to the technical field of microwave antenna design, and more specifically relates to a zero-crossing scanning leaky-wave antenna.

Background technique

The leaky wave antenna is a typical traveling wave antenna. Its radiation is the radiation generated when the electromagnetic wave propagates along the traveling wave structure, so it is called leaky wave. It is mainly divided into uniform or quasi-uniform structure leaky wave antenna and periodic structure leaky wave antenna. . Leaky wave antenna is characterized by good directional radiation ability and frequency scanning ability. Microwave circuit integrated processing has been widely used in high-resolution radar, automotive anti-collision radar, communication systems, sensors and other fields, especially in beam scanning occasions. However, the uniform structure leaky wave antenna can only realize forward scanning, that is, the beam direction scans from the side to the end with the frequency, and most of the electromagnetic energy in the side beam direction is reflected back to the feeder port, and the side scanning cannot be realized; the periodic structure leaky wave antenna Although backward and forward scanning can be realized, due to the large loss in the side-fire direction, the radiation efficiency is greatly reduced, showing the so-called "open stop band" phenomenon. How to realize continuous scanning across the zero point of the beam needs to be further studied.

Artificial surface plasmon polaritons (Spoof Surface Plasmon Polaritons, SSPPs) are artificially generated surface waves that propagate along the surface of metal media. The SSPPs transmission line is connected by periodic unit structures, which can support the efficient propagation of SSPPs, and has strong electromagnetic field confinement ability and adjustable dispersion characteristics. Compared with microstrip lines, coplanar waveguides, and slot lines, planar SSPPs transmission lines have a natural periodic structure, so they are more suitable for periodic leaky wave antennas. By periodically modulating the planar SSPPs transmission line, the harmonics satisfying the conditions can be radiated out to form a leaky wave antenna. According to the symmetric characteristics of the excited electromagnetic field, SSPPs can be divided into odd-mode (odd-symmetric electric field) and even-mode (even-symmetric electric field). Due to the phase cancellation of odd-mode, electromagnetic waves are difficult to radiate, and even-mode SSPPs are usually used to implement leaky wave antennas. However, like the leaky-wave antenna with the periodic structure mentioned above, there is a phenomenon of "opening the stop band", that is, the beam cannot be continuously scanned across the zero point from backward to forward.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention proposes a zero-crossing leaky-wave antenna, which mainly aims at the problem of opening the stop band phenomenon in the planar leaky-wave antenna, and adopts the sinusoidally modulated SSPPs transmission line to produce the leaky-wave effect, A periodical sinusoidal gap is opened on the bottom surface of the SIW-SSPPs leaky wave antenna to break the symmetry of the original structure, realize asymmetric characteristics, eliminate the phenomenon of opening the stop band, and realize cross-zero scanning.

To achieve the above object, the present invention provides a zero-crossing leaky-wave antenna, comprising: etching periodic slots on the upper metal of the substrate integrated waveguide to excite even-mode SSPPs to form a low-loss transmission line; performing periodic sine wave on the periodic slots Modulate to form a leaky wave antenna; etch a sinusoidal slot on the metal of the substrate integrated waveguide.

Among them, two rows of periodical slots are etched on the metal on the upper layer of the integrated waveguide on the substrate.

其中，w为两排金属通孔的间距。In some optional implementations, the diameter and period of the periodic slots of each row of substrate-integrated waveguides satisfy: d<p<2d, p/λ _c <0.1, p/λ _c >0.05, where d is the slot , p is the repetition period of the slit, λ _c is the cut-off wavelength of the equivalent rectangular waveguide of the substrate-integrated waveguide; the width of the equivalent rectangular waveguide of the substrate-integrated waveguide is:

Among them, w is the distance between two rows of metal vias.

In some optional implementations, the periodic sinusoidal modulation of the periodic slots is the modulation of the length of the periodic slots.

In some optional implementations, the sinusoidal slots etched on the lower metal of the substrate integrated waveguide are slots etched on the metal plate at the bottom of the SIW distributed along a sinusoid.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. The innovative sine-modulated SIW-SSPPs leaky-wave antenna of the present invention etches periodic sinusoidal gaps on the ground to achieve asymmetrical characteristics, so that the antenna beam can be continuously scanned across the zero point from the back to the front, and can be applied to broadband radiation Beam scanning antenna design;

2. The antenna proposed by the present invention has a simple structure, is easy to process, and can be directly integrated with a feed network and a planar microwave circuit.

Description of drawings

Fig. 1 is a front view of a zero-crossing scanning leaky-wave antenna provided by an embodiment of the present invention;

Fig. 2 is a back view of a zero-crossing scanning leaky-wave antenna provided by an embodiment of the present invention;

FIG. 3 is an S parameter diagram provided by an embodiment of the present invention;

Fig. 4 is a scanning direction diagram provided by an embodiment of the present invention;

Fig. 5 is a three-dimensional scanning direction diagram provided by an embodiment of the present invention;

Fig. 6 is a radiation efficiency diagram provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Embodiment one

As shown in Figure 1, a leaky-wave antenna with cross-zero scanning etches periodic slots on the upper metal of the substrate integrated waveguide to excite even-mode SSPPs to form a low-loss transmission line; periodic sinusoidal modulation is performed on the periodic slots to form a leaky-wave antenna ; Etching sinusoidal slots on the underlying metal of the integrated waveguide on the substrate.

In this embodiment, the substrate-integrated waveguide is composed of a dielectric substrate covered with metal plates up and down and two rows of periodic metal through holes (ie, periodic slots). In order to be equivalent to a metal waveguide, so that electromagnetic waves can propagate in a nearly closed environment without leakage, the diameter and period of the metal through-hole of the substrate-integrated waveguide should satisfy the following relationship:

d<p<2d (1)

p/ _λc <0.1 (2)

p/ _λc >0.05 (3)

Equation (1) ensures the mutual independence between the metal vias, and at the same time ensures that the electromagnetic wave propagates in the medium without energy leakage; Equation (2) ensures that the distance between the metal vias will not cause the stop band effect; Equation (3) ensures the mechanical strength of the substrate-integrated waveguide and avoids excessively dense metal vias. Among them, d is the diameter of the metal via, p is the repetition period of the metal via, and λ _c is the cut-off wavelength of the rectangular waveguide equivalent to the integrated waveguide on the substrate. The formula for calculating the width of a rectangular waveguide equivalent to a substrate-integrated waveguide is:

λ _c can be calculated by W _eff . Among them, w is the distance between two rows of metal vias.

Periodic slits are obtained by etching metal slits on the upper metal of the SIW, and are used to transmit SSPPs modes. The length, width and spacing of the slits determine the upper limit cut-off frequency of electromagnetic waves transmitted.

The above sinusoidal modulation is a modulation of the length of the periodic slot.

The above-mentioned sinusoidal slots are slots etched on the metal plate on the bottom surface of the SIW and distributed according to a sinusoidal curve.

The cross-zero point scanning leaky wave antenna provided by the present invention performs leaky wave radiation through the fast wave in the infinite space harmonic excited by the sinusoidal modulated SIW-SSPPs transmission line, and then breaks the symmetry of the structure through the periodic sinusoidal gap etched on the bottom surface of the SIW , so that the beam scans from backward to forward with the frequency, that is, to realize continuous scanning across the zero point. The antenna adopts the SIW structure, which has the advantages of low loss, simple structure, and easy integration with the feed structure, and the strong binding of SSPPs to electromagnetic waves further reduces the loss.

Embodiment two

This example takes the design of Ku-band cross-zero scanning leaky-wave antenna as an example to illustrate.

As shown in Figures 1 and 2, the zero-crossing scanning leaky-wave antenna structure provided by the present invention is mainly composed of a substrate integrated waveguide (SIW), a sinusoidally modulated periodic slot structure and a sinusoidal slot. The SSPPs mode is generated by the metal etching periodic gap on the upper layer of the SIW, and the amplitude of the gap is sinusoidally modulated to excite the infinite space mode, and the fast wave component in it produces a leaky wave. The metal etching sinusoidal gap on the bottom surface of SIW breaks the symmetry.

TE₁₀模式的截止频率为：

由S₁₁和S₂₁曲线可看出，13GHz至16GHz频段内，天线的S₁₁和S₂₁均较低，表明能量大部分被辐射。Figure 3 shows the S ₁₁ and S ₂₁ curves of the antenna. From formula (4), the equivalent width of the SIW structure can be obtained as

The cutoff frequency for TE ₁₀ mode is:

It can be seen from the S ₁₁ and S ₂₁ curves that in the 13GHz to 16GHz frequency band, the S ₁₁ and S ₂₁ of the antenna are relatively low, indicating that most of the energy is radiated.

Figure 4 and Figure 5 are the two-dimensional pattern and the three-dimensional pattern in the 14.8GHz-16.3GHz frequency band respectively. It can be seen that the present invention realizes continuous scanning across the zero point from backward to forward, the beam gain is from 4.56dB (14.8GHz) to 7.78dB (15.7GHz), and the scanning range of -18° to 58° is 76° in total.

Figure 6 is a graph of antenna radiation efficiency. It can be seen that the radiation efficiency of the antenna remains above 70%, and in the side-fire direction, the radiation efficiency is above 80%, indicating that the antenna has a continuous scanning function across zero points.

It should be pointed out that according to the needs of implementation, each step/component described in this application can be split into more steps/components, and two or more steps/components or part of the operations of steps/components can also be combined into a new Step/component, to realize the object of the present invention.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (2)

1. A zero-crossing scanning leaky-wave antenna, comprising: the substrate integrated waveguide is composed of a dielectric substrate and two rows of periodic metal through holes, wherein the dielectric substrate is covered with metal plates up and down, periodic metal gaps are etched on the upper layer metal of the substrate integrated waveguide, periodic sine modulation is carried out on the periodic metal gaps, and a leaky-wave antenna is formed; etching gaps distributed according to a sine curve on the lower layer metal of the substrate integrated waveguide;

each row of baseThe diameter and the period of the periodic metal through hole of the chip integrated waveguide both meet the following requirements: d < p < 2d, p/lambda _c ＜0.1、p/λ _c Is greater than 0.05, wherein d is the diameter of the metal through hole, p is the repetition period of the metal through hole, and lambda _c A cut-off wavelength of a rectangular waveguide equivalent to the substrate integrated waveguide; the width of the equivalent rectangular waveguide of the substrate integrated waveguide is as follows:

wherein w is the distance between two rows of metal through holes.

2. The cross-zero scanning leaky-wave antenna as claimed in claim 1, wherein the periodic sinusoidal modulation of the periodic metal slot is a modulation of a length of the periodic metal slot.

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