CN111786131A - A Broadband Quasi-Endfire Microstrip Yagi Antenna - Google Patents

Abstract

The invention discloses a broadband quasi-endfire microstrip Yagi antenna, comprising a top metal structure, a second metal structure, a third metal structure, a bottom metal structure, a first layer of dielectric substrate, a second layer of dielectric substrate and a coaxial Wire. The top metal structure includes a first strip-type metal patch, a first rectangular metal patch, a double rectangular metal patch, and a second strip-type metal patch. The double-rectangular metal patch and the double-layered metal patch structure composed of the first rectangular metal patch and the second layer of metal structure connected by the metallized through holes constitute the driving unit. The first strip-type metal patch on the left side of the drive unit constitutes the guide unit. The second strip-type metal patch on the right side of the drive unit constitutes the reflection unit. The third strip-type metal patch, the second layer of dielectric substrate and the metal ground form a microstrip line as a feeding structure. The invention has a wider bandwidth, can greatly reduce the influence of the size of the metal carrier on the beam pointing of the antenna, and improve the adaptability of the antenna on the metal carrier.

Description

A Broadband Quasi-Endfire Microstrip Yagi Antenna

technical field

The invention relates to various microwave communication fields, in particular to a broadband quasi-endfire microstrip Yagi antenna.

Background technique

Microstrip Yagi antennas are widely used in wireless communication systems because of their strong directivity, high gain, high front-to-back ratio, and strong anti-interference ability. In order to obtain standard end-fire radiation, the microstrip Yagi antenna usually uses defective metal ground, and its end-fire characteristics and bandwidth can be effectively guaranteed. However, the environmental adaptability of such antennas is weak, especially when the antenna is attached to a metal carrier, its end-fire characteristics and bandwidth will be greatly affected, and due to the different sizes of the metal carrier, the impact will also vary. The microstrip Yagi antenna with complete metal ground is designed considering the influence of the metal background. The antenna can be placed on the metal surface, and the quasi-endfire radiation characteristics can still be obtained in terms of radiation characteristics. It can be seen that the quasi-endfire microstrip Yagi antenna has good environmental adaptability and is less affected by the metal carrier, so it has received more and more attention.

In order to achieve the quasi-endfire radiation characteristics of the microstrip Yagi antenna, the antenna is usually composed of three parts: a reflection unit, a driving unit and a guiding unit, and the resonant frequencies of each unit are different from each other, which is convenient to adjust the far-field synthesis of each unit. Phase contribution. For each unit structure, there are mainly single metal patches, metal patches with metallized vias or strip grooves, multi-metal patches, etc. These microstrip Yagi antennas can achieve the required quasi-endfire radiation, but there are The problem of relatively narrow bandwidth. In addition, in order to easily realize the quasi-endfire radiation of the antenna, the elements of the current microstrip Yagi antenna are arranged along the polarization direction, but the disadvantage is that the beam direction is easily affected by the size of the metal ground, to a large extent Reduced adaptability to metal environments. In order to increase the bandwidth of the quasi-endfire microstrip Yagi antenna and reduce the influence of the antenna beam pointing with the size of the metal carrier, it is necessary to propose a new broadband quasi-endfire microstrip Yagi antenna.

SUMMARY OF THE INVENTION

Purpose of the invention: Aiming at the problems that the current quasi-endfire microstrip Yagi antenna has a narrow bandwidth and the antenna beam pointing is greatly affected by the size of the metal carrier, a broadband quasi-endfire microstrip Yagi antenna is proposed, and the antenna beam pointing is affected by the size of the metal carrier. impact is greatly reduced.

Technical solution: a broadband quasi-endfire microstrip Yagi antenna, comprising a top metal structure, a second metal structure, a third metal structure, a bottom metal structure, a first layer of dielectric substrate, a second layer of dielectric substrate and a coaxial cable ;

The top-layer metal structure is located on the upper surface of the first layer of dielectric substrate, and includes a first strip-type metal patch, a first rectangular metal patch, a double rectangular metal patch with spacing, and a second strip-type metal patch; the second strip-type metal patch; The layered metal structure is composed of a second rectangular metal patch, which is located on the lower surface of the first layer of dielectric substrate, and is connected to the first rectangular metal patch through a metallized through hole located at the midpoint of the two sides of the metal patch. The third layer of metal structure is composed of a third strip-type metal patch, which is located on the upper surface of the second layer of dielectric substrate; the bottom metal structure is a metal ground with circular holes, which is located on the second layer of dielectric substrate. the lower surface of the coaxial line; the inner conductor of the coaxial line is connected to the third strip-type metal patch through the circular hole;

The double-rectangular metal patch with spacing and the double-layer metal patch structure formed by the first rectangular metal patch and the second rectangular metal patch connected by the metallized through holes constitute a driving unit of the antenna; The first strip-type metal patch on the left side of the driving unit constitutes a guiding unit of the antenna; the second strip-type metal patch located on the right side of the driving unit constitutes a reflection unit of the antenna; the The third strip-type metal patch, the second layer of dielectric substrate and the metal ground form a microstrip line, which is used as the feed structure of the antenna. The central axis of the metal patch is parallel; wherein, the driving unit, the guiding unit, and the reflecting unit are arranged along the direction perpendicular to the polarization direction, and are distributed symmetrically in the polarization direction.

Beneficial effects: 1. The driving unit of the antenna is composed of double rectangular metal patches and double-layer metal patches, and is coupled and excited by the half-wavelength microstrip line, so as to obtain multiple working modes, expand the bandwidth of the antenna, and promote the drive The unit itself has a certain oblique radiation characteristic, which is beneficial to form a quasi-endfire radiation characteristic on the H-plane of the antenna.

2. The guiding unit and reflecting unit composed of strip-type metal patches are arranged on both sides of the driving unit, and are arranged along the direction perpendicular to the polarization direction (H plane), forming quasi-end-fire radiation characteristics on the H plane, improving the The adaptability of the antenna to the size of the metal carrier is improved.

3. By loading metallized through holes at the midpoints of both sides of the double-layer rectangular metal patch, the electric field distribution of the double-layer metal patch is adjusted, thereby reducing the side lobe level of the antenna.

4. The guiding unit, driving unit and reflecting unit of the antenna are symmetrically distributed in the polarization direction, which ensures that the E-plane pattern is not inclined.

Description of drawings

1 is a cross-sectional view of an antenna of the present invention;

Fig. 2 is the top metal structure diagram of the antenna of the present invention;

Fig. 3 is the metal structure diagram of the second layer of the antenna of the present invention;

Fig. 4 is the metal structure diagram of the third layer of the antenna of the present invention;

Fig. 5 is the bottom metal structure diagram of the antenna of the present invention;

Fig. 6 is the simulation matching and gain curve of the antenna of the present invention;

Fig. 7 is the radiation angle curve of the antenna beam of the present invention under different metal ground sizes;

Figure 8 is the simulated pattern of the antenna elevation plane; wherein, Figure (a) is the radiation pattern of 5GHz, Figure (b) is the radiation pattern of 5.5GHz, Figure (c) is the radiation pattern of 6GHz, Figure (d) Radiation pattern for 6.4GHz.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings.

A broadband quasi-endfire microstrip Yagi antenna, as shown in Figure 1, includes a top metal structure 1, a second metal structure 2, a third metal structure 3, a bottom metal structure 4, a first layer of dielectric substrate 13, a Two-layer dielectric substrate 16 and coaxial lines 17 .

As shown in FIG. 2, the top metal structure 1 is located on the upper surface of the first layer dielectric substrate 13, and includes a first strip-type metal patch 5, a first rectangular metal patch 6, a double rectangular metal patch 7 with spacing, The second strip-type metal patch 8 . As shown in FIG. 3 , the second-layer metal structure 2 is composed of a second rectangular metal patch 9, which is located on the lower surface of the first-layer dielectric substrate 13, and is connected through a metallization at the midpoint of the two sides of the metal patch. The hole 14 is connected to the first rectangular metal patch 6 . As shown in FIG. 4 , the third-layer metal structure 3 is composed of a third strip-type metal patch 10 and is located on the upper surface of the second-layer dielectric substrate 16 . As shown in FIG. 5 , the underlying metal structure 4 is a metal ground 12 with a circular hole 11 and is located on the lower surface of the second-layer dielectric substrate 16 . The inner conductor 15 of the coaxial line 17 is connected to the third strip-type metal patch 10 through the circular hole 11 .

The double-rectangular metal patch 7 with spacing and the double-layered metal patch structure formed by the first rectangular metal patch 6 and the second rectangular metal patch 9 connected by the metallized through holes 14 constitute the driving unit of the antenna. The first strip-type metal patch 5 located on the left side of the driving unit constitutes the guiding unit of the antenna. The second strip-type metal patch 8 located on the right side of the driving unit constitutes the reflection unit of the antenna. The third strip-type metal patch 10, the second-layer dielectric substrate 16 and the metal ground 12 form a microstrip line, which serves as the feeding structure of the antenna. The axis is parallel to the central axis of the double rectangular metal patch. Wherein, the driving unit, the guiding unit, and the reflecting unit are arranged along the direction perpendicular to the polarization direction, and are distributed symmetrically in the polarization direction.

When the antenna is working, the signal feeds the microstrip line through the coaxial line 17, so that it exhibits a half-wave standing wave distribution, and thus couples and excites the TM ₂₀ mode of the double rectangular metal patch 7, which further excites the double-layer metal patch 6, 9 in TM ₁₀ mode. Since the driving unit and its feeding structure have multiple operating modes, a wider operating bandwidth can be obtained. At the same time, since the driving unit is composed of double rectangular metal patches 7 and double-layer metal patches 6 and 9 in a coupling relationship, which have oblique radiation characteristics, after adding the assistance of the guiding unit and the reflecting unit, the When the antennas can be arranged along the non-polarized direction, the quasi-endfire radiation characteristics can also be better achieved. In this case, the influence of the size of the antenna metal ground 12 on the antenna beam direction will be greatly reduced, which can effectively improve the adaptability on the metal carrier.

The substrate used in this example is an RO4003C substrate with a dielectric constant of 3.38 and a loss angle of 0.0027. The length of the antenna is 100mm, the width is 70mm, and the thickness is 5mm, that is, the size is 1.88λ ₀ ×1.31λ ₀ ×0.09λ ₀ when the center frequency is 5.63GHz. The schematic diagram of the antenna structure is shown in Figure 1 to Figure 5, and the simulated matching response and gain are shown in Figure 6. The 10-dB matching bandwidth is 4.75GHz-6.48GHz, that is, the relative bandwidth reaches 30.8%, and the gain range in the frequency band is 8.6-10.9dBi. FIG. 7 is a curve of the beam tilt angle of the antenna of this embodiment as a function of frequency, and the beam pointing angle is 23°-45° within the matching bandwidth. In the case of expanding the metal ground area by 17 times, the beam pointing angle within the matching bandwidth is 21°-56°, indicating that the metal ground has little influence on the beam pointing. 8 is the antenna pattern of the antenna of this embodiment at 5GHz, 5.5GHz, 6GHz, and 6.4GHz. It can be seen that the front-to-back ratio of the antenna in the elevation plane is less than -16dB, and the cross-polarization is less than -22dB.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (1)

1. a broadband quasi-endfire microstrip Yagi antenna, is characterized in that, comprises top metal structure (1), second metal structure (2), third metal structure (3), bottom metal structure (4), a first layer of dielectric substrate (13), a second layer of dielectric substrate (16) and a coaxial line (17); The top-layer metal structure (1) is located on the upper surface of the first-layer dielectric substrate (13), and includes a first strip-type metal patch (5), a first rectangular metal patch (6), and double rectangular metal patches with spacing (7), a second strip-type metal patch (8); the second-layer metal structure (2) is composed of a second rectangular metal patch (9), which is located on the lower surface of the first-layer dielectric substrate (13) , and is connected to the first rectangular metal patch (6) through a metallized through hole (14) located at the midpoint of the two sides of the metal patch; the third-layer metal structure (3) is composed of a third strip type A metal patch (10) is formed and is located on the upper surface of the second layer of dielectric substrate (16); the underlying metal structure (4) is a metal ground (12) with circular holes (11), located on the second layer of dielectric substrate (12) the lower surface of the base plate (16); the inner conductor (15) of the coaxial line (17) is connected to the third strip-type metal patch (10) through the circular hole (11); The double rectangular metal patch (7) with spacing and the double rectangular metal patch (6) and the second rectangular metal patch (9) connected by the metallized through holes (14) The layered metal patch structure constitutes the drive unit of the antenna; the first strip-type metal patch (5) located on the left side of the drive unit constitutes the guide unit of the antenna; the first strip type metal patch (5) located on the right side of the drive unit The two strip-type metal patches (8) constitute the reflection unit of the antenna; the third strip-type metal patch (10), the second-layer dielectric substrate (16) and the metal ground (12) constitute a microstrip line, which serves as a The feeding structure of the antenna, the feeding structure is located directly below the double rectangular metal patch (7) with spacing, and the central axis is parallel to the central axis of the double rectangular metal patch; wherein, the driving unit, the guiding unit, the reflection The cells are aligned perpendicular to the polarization direction and are symmetrically distributed in the polarization direction.

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