CN115275625A - A broadband metasurface antenna loaded with parasitic patches - Google Patents

Abstract

The invention belongs to the technical field of wireless communication, and particularly relates to a broadband super-surface antenna loaded with a parasitic patch. In order to solve the problem that the impedance bandwidth of the conventional antenna is small, the antenna comprises two dielectric plates and three metal layers. The upper layer of metal comprises 3-by-3 square metal patch arrays and 4 parasitic patches to form the super-surface radiating unit. And etching the elliptical coupling gap by the middle metal layer. The lower metal is a microstrip line feed structure. By loading four parasitic patches on the upper layer and changing the size of part of the square patches, the impedance matching of the antenna is improved, and the bandwidth of the antenna is increased. The antenna works at 4.41GHz-7.61GHz, and the relative bandwidth reaches 53.2%. The peak gain reaches 10.2dBi.

Description

A Broadband Metasurface Antenna Loaded with Parasitic Patch

technical field

The invention belongs to the technical field of wireless communication, and in particular relates to a broadband metasurface antenna loaded with parasitic patches.

Background technique

With the rapid development of wireless communication, global positioning system, satellite communication, personal communication and other communication systems put forward higher requirements for the broadband of the antenna. The broadband antenna can cover multiple frequency bands, which can reduce the number of antennas required by the communication system, thereby reducing the system weight and cost.

In recent years, many methods have been proposed to broaden the impedance bandwidth of antennas. Loading metasurfaces is an effective way to increase bandwidth, which has the advantages of low profile and multi-mode. For example, a metasurface-based low-profile broadband planar circularly polarized folded transmit array antenna achieves a peak gain of up to 10.1dBi and a 3dB gain bandwidth of 22% (Jin Yang, ShangTong Chen, Mao Chen, Jun Chen Ke, Ming Zheng Chen , Cheng Zhang, Rui Yang, Xin Li, Qiang Cheng, and Tie Jun Cui. Folded Transmitarray Antenna with CircularPolarization Based on Metasurface. IEEE Transactions on Antennas and Propagation, 2021, 69(2):806). A metasurface-based low-profile broadband mode-diversity antenna with isolation better than 38dB while maintaining 20.24% of the operating bandwidth (Jianfeng Liu, Zibin Weng, Zhi-Qiang Zhang, Yonghui Qiu, Yi-Xuan Zhang, and Yong- Chang Jiao. A Wideband Pattern Diversity Antenna with a Low Profile Based on Metasurface. IEEE Antennas and Wireless Propagation Letters, 2021, 20(3):303), but the realized impedance bandwidth is small.

In view of this, it is necessary to propose a broadband metasurface antenna with a simple structure to meet the development needs of wireless communication.

Contents of the invention

The object of the present invention is to provide a broadband metasurface antenna loaded with parasitic patches, which has good broadband impedance characteristics, simple antenna structure and easy processing.

In order to achieve the above object, the present invention adopts the following technical solutions:

A broadband metasurface antenna loaded with parasitic patches, comprising an upper metal layer, a first dielectric layer, an intermediate metal layer, a second dielectric layer, and a lower metal layer arranged sequentially from top to bottom;

The upper metal layer is composed of two sets of square metal patches and a set of parasitic patches. The first set of square metal patches includes five square metal patches distributed in a cross shape. The second set of square metal patches The chip includes four square metal patches, the four square metal patches are respectively located in the vacancies of the five square metal patches distributed in a cross shape, and together with the five square metal patches form a 3*3 super In the surface unit, the group of parasitic patches includes four parasitic patches, which are respectively located around the 3*3 metasurface unit and adjacent to the first group of square metal patches; the center of the middle metal layer is etched with The elliptical coupling slot, the lower metal layer is a microstrip feeder.

Further, the upper metal layer is located at the center of the first dielectric layer.

Further, the size of the first group of square metal patches and the second group of square metal patches are different.

Further, the microstrip feeder is a T-shaped microstrip feeder.

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

By loading four parasitic patches on the upper layer, a new resonance frequency appears near 6 GHz, and the resonance point can be merged with the original resonance point of the antenna through parameter adjustment. Therefore, the impedance bandwidth of the parasitic patch antenna proposed by the present invention is relatively wide.

By changing the size of part of the square patch, the impedance matching of the antenna is improved. The realized antenna achieves an impedance bandwidth of 53.2% (|S ₁₁ |≤-10dB).

The elliptical slot is located in the center of the middle metal layer, and acts as a coupling feed to the upper metasurface unit. Compared with the rectangular coupling slot, it can better improve the overall impedance matching of the antenna, thereby achieving a wider impedance bandwidth.

Description of drawings

Fig. 1 is a structural representation of the present invention;

In the figure: 1-upper metal layer, 2-first dielectric layer, 3-middle metal layer, 4-second dielectric layer, 5-lower metal layer, 6-first group of square metal patches, 7-second group Square metal patch, 8-parasitic patch, 9-elliptical coupling slot, 10-microstrip feeder;

Fig. 2 is |S ₁₁ | of the broadband antenna of the present invention;

Fig. 3 is the current distribution of the broadband antenna of the present invention;

Fig. 4 is the impedance characteristic of broadband antenna of the present invention;

Fig. 5 is the influence of the width b of the first group of square metal patches of the present invention on the antenna |S ₁₁ | and impedance matching;

Fig. 6 is the influence of the width c of the second group of square metal patches on the antenna |S ₁₁ | and impedance matching according to the present invention;

Fig. 7 shows the influence of the elliptical coupling slot of the present invention on the antenna |S ₁₁ | and impedance matching;

Fig. 8 is the gain of the broadband antenna described in the present invention;

Fig. 9 is the radiation pattern of the broadband antenna according to the present invention at 4.75GHz, 6.03GHz and 7.19GHz;

Detailed ways

Example 1

As shown in Figure 1, a broadband metasurface antenna loaded with parasitic patches includes an upper metal layer 1, a first dielectric layer 2, an intermediate metal layer 3, a second dielectric layer 4, and a lower metal layer arranged in sequence from top to bottom. layer 5;

The upper metal layer 1 is composed of two groups of square metal patches and a group of parasitic patches, the first group of square metal patches 6 includes five square metal patches distributed in a cross shape, the second group of square metal patches 6 The metal patch 7 includes four square metal patches, and the four square metal patches are respectively located in the vacancies of the five square metal patches distributed in a cross shape, and together with the five square metal patches, they form a 3 *3 metasurface unit, the group of parasitic patches includes four parasitic patches 8, respectively located around the 3*3 metasurface unit and adjacent to the first group of square metal patches 6; the upper metal layer 1 is located at the center of the first dielectric layer 2. The middle metal layer 3 is etched with elliptical coupling gaps 9 , the lower metal layer 5 is a microstrip feeder 10 , and the first group of square metal patches 6 and the second group of square metal patches 7 have different sizes. The microstrip feeder 10 is a T-shaped microstrip feeder.

During specific implementation, the parameters of the antenna structure are shown in Table 1:

Table 1 Antenna structure parameters (unit: mm)

parameter a b c e f h value 55 8 8.5 0.65 0.85 twenty four parameter g k l m z w value 2.3 5 8 1.1 3.454 0.508

The two-layer dielectric plate of the antenna is made of Rogers RO4003C material with a dielectric constant of 3.55.

The square metal patch, the parasitic patch, and the middle metal layer are all metallic copper.

Figure 2 shows the frequency characteristics of the broadband metasurface antenna |S ₁₁ | loaded with parasitic patches (curve 2 in the figure), where the abscissa represents the frequency variable in GHz, and the ordinate represents the amplitude variable in dB. For the convenience of comparison, the |S ₁₁ | of the metasurface antenna without parasitic patches is also shown in the figure (curve 1 in the figure). It can be seen that for an antenna without a parasitic patch, there are three resonant frequencies f ₁ =4.8GHz, f ₂ =6.6GHz, and f ₃ =7.3GHz. The three operating frequency bands are separated from each other to form three separate frequency bands. When the parasitic patch is loaded, the impedance matching of the antenna is improved, and a new resonance frequency appears at 6GHz, and multiple frequency bands are connected together, which greatly broadens the working frequency band of the antenna. The working frequency band of the final antenna is 4.41GHz-7.61GHz, the absolute bandwidth is 3.2GHz, and the relative bandwidth is 53.2%.

Figure 3 shows the electric field distribution of the antenna at 6GHz. It can be seen from Fig. 3(a) that when no parasitic patch is loaded, the electric field is mainly concentrated on both sides of the metasurface units P1 and P2. When the parasitic patch P3 is loaded ((b) in Fig. 3), the electromagnetic waves are distributed around the metasurface units P1 and P2, and most of them are concentrated near P3. At the same time, the electromagnetic waves between P1, P2, and P3 are greatly enhanced. (P1, P2, and P3 respectively represent the first group of square metal patches, the second group of square metal patches, and parasitic patches).

Figure 4 shows the impedance characteristics of the wideband metasurface antenna loaded with parasitic patches and compares it with the results without loading the parasitic patches. In the figure, the abscissa represents the frequency variable, and the unit is GHz, and the ordinate represents impedance, and the unit is ohm. When no parasitic patch is loaded, the impedance matching of the antenna at each resonant frequency is not good. For example, at 7.3GHz, the real part of the impedance can reach 131Ω. After loading the parasitic patch, the real part of the impedance of the antenna reaches around 50Ω in the range of 4.41GHz-7.61GHz, so that the impedance matching in this working range is improved.

Fig. 5 shows the effect of the width b of the first group of square metal patches on the antenna |S ₁₁ | and impedance matching. When b=7.5mm, when the antenna is at 7.4GHz, |S ₁₁ | is -6dB ((a) in Fig. 5), which does not drop to -10dB, and the bandwidth is narrow. When b=8.5mm, the antenna is at 6.9GHz, |S ₁₁ | is -9dB ((a) in Figure 5), and the bandwidth is narrow. When b=8mm, the real part of the impedance of the antenna reaches around 50Ω in the working frequency band ((b) in Figure 5), the impedance matching is good, and in the frequency range of 4.41GHz to 7.61GHz, |S ₁₁ |<-10dB , the widest absolute bandwidth was obtained ((a) in Figure 5).

Fig. 6 shows the effect of the width c of the second set of square metal patches on the antenna |S ₁₁ | and impedance matching. When c=8mm, the antenna is at 7.1GHz, |S ₁₁ | is -9dB ((a) in Figure 6), and the bandwidth is narrow. When c=9mm, the antenna is at 7GHz, |S ₁₁ | is -6.2dB ((a) in Figure 6), and the bandwidth is narrow. When c=8.5mm, the real part of the impedance of the antenna reaches around 50Ω in the working frequency band ((b) in Figure 6), the impedance matching is good, and the widest absolute bandwidth of 4.41GHz-7.61GHz is obtained (in Figure 6 ((b)) a)).

Figure 7 shows the effect of the elliptical coupling slot on the antenna |S ₁₁ | and impedance matching. And compared with the results when using rectangular coupling gap. When the middle layer uses a rectangular slot, the impedance matching of the antenna at each resonant frequency is not good, for example, at 7GHz, the real part of the impedance can reach 110Ω ((b) in Figure 7). Therefore, the working frequency bands of the antenna are three separate frequency bands of 4.3GHz-5.1GHz, 5.6GHz-6.3GHz, and 7.08GHz-7.4GHz ((a) in FIG. 7 ). After using the elliptical coupling slot, the real part of the impedance of the antenna reaches around 50Ω in the range, so that the impedance matching in the working range is improved, and the impedance bandwidth of the antenna reaches 4.41GHz-7.61GHz ((a) in Figure 7).

Fig. 8 shows the gain characteristics of the broadband metasurface antenna loaded with parasitic patches. In the figure, the abscissa represents the frequency variable, and the unit is GHz, and the ordinate represents the gain, and the unit is dBi. It can be seen that within the frequency range of 4.41GHz to 7.61GHz, the maximum gain is 10.2dBi.

Figure 9 shows the pattern of the broadband metasurface antenna loaded with parasitic patches, where (a) in Figure 9 is the pattern of the antenna at 4.75GHz, (b) in Figure 9 is the pattern of 6.03GHz, Figure 9 (c) is the pattern of 7.19GHz. It can be seen that as the frequency increases, the main polarization pattern of the antenna is basically undistorted.

Claims (4)

1. A broadband super-surface antenna loaded with parasitic patches is characterized by comprising an upper metal layer, a first dielectric layer, a middle metal layer, a second dielectric layer and a lower metal layer which are sequentially arranged from top to bottom;

the upper metal layer consists of two groups of square metal patches and a group of parasitic patches, the first group of square metal patches comprises five square metal patches which are distributed in a cross shape, the second group of square metal patches comprises four square metal patches which are respectively positioned at the vacant positions of the five square metal patches distributed in the cross shape and form a 3 x 3 super surface unit together with the five square metal patches, and the group of parasitic patches comprises four parasitic patches which are respectively positioned at the periphery of the 3 x 3 super surface unit and are adjacent to the first group of square metal patches; an elliptical coupling gap is etched in the center of the middle metal layer, and the lower metal layer is a microstrip feeder line.

2. The broadband super surface antenna loaded with parasitic patches of claim 1, wherein said upper metal layer is located at the center of the first dielectric layer.

3. The parasitic patch loaded broadband super surface antenna according to claim 1, wherein the first set of square metal patches and the second set of square metal patches are different in size.

4. The broadband super surface antenna loaded with parasitic patches as claimed in claim 1, wherein said microstrip feed line is a T-shaped microstrip feed line.

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