CN105789871A - Low-profile planar dipole antenna suitable for 4G LTE communication - Google Patents

Abstract

The present invention provides a low-profile planar dipole antenna suitable for 4G LTE communication. The traditional dipole antenna is transformed, and the part between the dipoles is similar to the radiation form of the Vivadi antenna. Under the planar dipole antenna A reflective back cavity is placed, and a frequency-selective surface reflector is added between the reflective back cavity and the planar dipole antenna. The present invention can significantly improve the antenna gain while achieving unidirectional radiation, so that the antenna gain can be significantly improved at high frequencies, so that the antenna maintains good beam convergence and high gain in the 4G LTE communication frequency band (700MHz-3200MHz), Front-to-back ratio, cross-polarization ratio characteristics.

Description

A low-profile planar dipole antenna suitable for 4G LTE communication

technical field

The invention relates to the communication field, in particular to a linearly polarized planar dipole antenna applied to 4G mobile communication.

Background technique

As people's demand for mobile communication service capabilities is getting higher and higher, on the basis of conventional 2G and 3G, the quasi-4G LTE band has begun to be put into commercial use; from the perspective of operators, in order to save investment and consider how to follow up It has increasingly become a trend to achieve scalability, compatibility, multi-system, and multi-system coexistence. This also puts forward higher requirements for base station antennas. In order to meet the frequencies of different standards, ultra-wideband base station antennas such as 700, 1710, and 2690MHZ frequency bands have been widely proposed and applied; at the same time, the broadbandization of base station antennas also helps reduce mobile Communication equipment, reduce the number of antennas, and reduce the amount of installation and maintenance projects, thereby reducing the operating costs of each operator, and to realize the broadband of the base station antenna, the first thing to face is the bandwidth expansion of the radiation unit as its core component The problem, how to maintain high gain, beam convergence consistency, good front-to-back ratio characteristics and high cross-polarization ratio in the entire broadband frequency band is not a small challenge.

Document 1 "Shi-Gang Zhou, Member, IEEE, and Jian-Ying Li, "Low-Profile and Wideband Antenna", IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL.10, 2011, Pages: (373-376)" adopted micro The technique of widening the bandwidth of the dipole antenna with the line feed, but its gain varies greatly within the frequency band.

Literature 2 "S.W.Qu, J.L.Li, Q.Xue, and C.H.Chan, "Wideband cavity-backed bowtie antenna with pattern improvement," IEEE Trans. Antennas Propag., vol.56, no.12, pp.3850–3854, Dec. .2008."A microstrip balun feed was adopted, and a circular reflective back cavity was used. But its antenna standing wave cannot meet the 4G antenna bandwidth, and its maximum gain is low in the high frequency band.

Document 3 "T.G.Ma and S.K.Jeng, "A printed dipole antenna with tapered slot feed for ultrawide-band applications," IEEE Trans. Antennas Propag., vol.53, no.11, pp.3833–3836, Nov.2005." The medium antenna transmits energy to two stacked microstrip patches through the SMA head and the microstrip line feed. The antenna bandwidth meets the requirements, but this method cannot guarantee the unidirectional radiation of the antenna, so the antenna gain is low.

To sum up, the existing literature fails to propose a linearly polarized antenna that can effectively achieve higher gain and beam convergence in the case of wider bandwidth.

Contents of the invention

In order to overcome the deficiencies of the prior art, the present invention provides a planar dipole ultra-wideband antenna, which has the characteristics of high gain, consistent beam convergence, good front-to-back ratio characteristics and high cross-polarization ratio, and can meet the requirements of 4G LTE antenna bandwidth and Gain requirements within the bandwidth.

The technical solution adopted by the invention to solve the technical problem is: comprising a planar dipole antenna, a frequency-selective surface reflection plate and a metal reflection back cavity.

The planar dipole antenna includes a circular metal coupling patch, a No. 1 square dielectric substrate, a microstrip transmission line, a cylindrical metal post, an SMA connector, and two elliptical metal patches; the two elliptical metal patches The patch is closely attached to the lower surface of the No. 1 square dielectric substrate, and the two oval metal patches are not connected to each other; the upper surface of the No. 1 square dielectric substrate is closely attached to a circular metal coupling patch, and the diameter of the circular metal coupling patch is One end of the microstrip transmission line is connected, and the other end of the microstrip transmission line is connected to a cylindrical metal post. The cylindrical metal post passes through the No. 1 square dielectric substrate and an oval metal patch, and connects to the SMA connector;

The frequency-selective surface reflector includes a No. 2 square dielectric substrate and a number of metal patches, the metal patches are periodically arranged on the upper surface of the No. 2 square dielectric substrate, and the No. 2 square dielectric substrate is facing the position of the SMA connector. There are through holes, and the through holes are not covered by metal patches;

The metal reflective back cavity includes a bottom reflector and a side metal plate, and the bottom reflector has a through hole facing the SMA connector; the side metal plate is enclosed around the upper surface of the bottom reflector, and the planar dipole antenna The frequency selective surface reflector and the frequency selective surface reflector are fixed in the space enclosed by the bottom reflector and the side metal plate, and the geometric centers of the planar dipole antenna and the frequency selective surface reflector are projected on the geometric center of the bottom reflector.

The beneficial effects of the present invention are: adding a metal reflective back cavity to the bottom of the dipole 4G LTE antenna in the online polarization can significantly improve the antenna gain while realizing unidirectional radiation, and adding an FSS reflective surface between them can make the antenna in the The high-frequency gain is significantly improved. Combining the above two reflector structures, the antenna can maintain good beam convergence and high gain, front-to-back ratio, and cross-polarization ratio in the 4G LTE communication frequency band (700MHz-3200MHz).

Description of drawings

Fig. 1 is a top view of the dipole antenna of the present invention.

Fig. 2 is an overall sectional view of the dipole antenna of the present invention.

Fig. 3 is the FSS reflection structure of the dipole antenna in the present invention.

Fig. 4 is a metal-backed cavity reflection structure for a dipole antenna according to the present invention.

Fig. 5 is the standing wave VSWR of the 4G LTE antenna of the present invention.

FIG. 6 is a radiation pattern at a frequency of 700 MHz of the 4G LTE antenna of the present invention.

Fig. 7 is a radiation pattern diagram of the 4G LTE antenna of the present invention at a frequency of 1200MHz.

Fig. 8 is a radiation pattern diagram of the 4G LTE antenna of the present invention at a frequency of 1700MHz.

FIG. 9 is a radiation pattern diagram of the 4G LTE antenna of the present invention at a frequency of 2200MHz.

Fig. 10 is a radiation pattern diagram of the 4G LTE antenna of the present invention at a frequency of 2700MHz.

Fig. 11 is a radiation pattern diagram of the 4G LTE antenna of the present invention at a frequency of 3200MHz.

Fig. 12 is a curve of the maximum radiation direction gain of the 4G LTE antenna of the present invention as a function of frequency.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, and the present invention includes but not limited to the following embodiments.

The ultra-broadband planar dipole antenna of the present invention is characterized in that, on the one hand, the traditional pair of dipole antennas is deformed, and the part between the dipoles is similar to the radiation form of the Vivadi antenna, and the second aspect is below the planar dipole antenna Place a reflective back cavity, and the third aspect is to add an FSS (Frequency selective surface) between the reflective back cavity and the antenna. From these three aspects, the purpose of widening the radiation bandwidth of the antenna and improving the directional gain of the antenna in the entire frequency band is achieved.

The invention mainly includes three main parts: a planar dipole antenna, a frequency selective surface (FSS) reflection plate, and a metal reflection back cavity. The installation sequence of these three parts from top to bottom is planar dipole antenna-frequency selective surface (FSS) reflector-metal reflector back cavity, and their centers are all on the same vertical line.

The planar dipole antenna consists of a circular metal coupling patch 1, a square dielectric substrate 2, a microstrip transmission line 3, a cylindrical metal post 4, a first elliptical metal patch 5, a second elliptical metal patch 6, SMA connector 7 composition. A first elliptical metal patch 5 and a second elliptical metal patch 6 are closely attached to the lower surface of the No. 1 square dielectric substrate 2 , and the first elliptical metal patch 5 and the second elliptical metal patch 6 are not connected to each other. The upper surface of No. 1 square dielectric substrate 2 is closely attached to a circular metal coupling patch 1, and the radial direction of the circular metal coupling patch 1 is connected to one end of a microstrip transmission line 3, and the other end of the microstrip transmission line 3 is connected to a cylindrical metal column 4. Shaped metal post 4 passes through No. 1 square dielectric substrate 2 and second elliptical metal patch 6 to connect with SMA connector 7 . The four corners of No. 1 square dielectric substrate 2 are respectively provided with through holes 10 .

The frequency selective surface (FSS) reflector is composed of a second square dielectric substrate 8 and metal patches 9 arranged on the upper surface of the second square dielectric substrate 8 with equal intervals and periodic intervals. The middle part of No. 2 square dielectric substrate 8 has a through hole 13 (the through hole must not be covered by a metal patch), and the position of the through hole is facing the SMA connector 7 . The four corners of the second square dielectric substrate 8 are respectively provided with through holes 10 , and the positions are directly opposite to the through holes 10 of the first square dielectric substrate 2 .

The metal reflection back cavity is composed of a bottom reflection plate and a side metal plate 12 , and a through hole 14 is opened on the bottom reflection plate, and the position of the through hole is facing the SMA connector 7 . The side metal plate 12 is enclosed around the upper surface of the bottom reflector, the planar dipole antenna and the frequency selective surface (FSS) reflector are placed in the space enclosed by the bottom reflector and the side metal plate 12, and the support The columns pass through the through holes 10 at the four corners of the No. 1 square dielectric substrate 2 and the No. 2 square dielectric substrate 8, and are fixed on the bottom reflector.

In this embodiment, the center frequency point of the antenna is 2000MHz, wherein the No. 1 square dielectric substrate 2 adopts a material with a dielectric constant ε _r = 2.2, the length w of the bottom surface is 220.0mm, and the height h is 1.0mm; The sheet 1 is circular, the radius R1 of the metal patch is 16.5 mm, and the geometric center of the metal patch is 20.4 mm away from the geometric center of the No. 1 square dielectric substrate 2; one end of the microstrip transmission line 3 is radial to the circular metal patch 1 connected, the other end is 31.6mm away from the geometric center of the No. The dielectric substrate 2 is connected to the SMA connector 7; the minor axis length of the elliptical metal patches 5 and 6 attached to the square dielectric substrate 2 is 34.0mm, the ratio of the major and minor axes is 1.2, and the elliptical metal patches 5 and 6 are The distance between the gaps is 0.6 mm, and four through holes 10 with a radius R2 = 1.25 mm are drilled at a position 3.0 mm away from the edge of the No. 1 square dielectric substrate 2 .

No. 2 square dielectric substrate 8 adopts the material with dielectric constant ε _r = 4.4, its bottom surface length w is 220.0mm, height h1 is 1.0mm, and distance h2 from No. 1 square dielectric substrate 2 is 33.0mm, close to its top Several metal patches 9 are square, and the side length w3 is 14.0 mm. The distance between each metal patch 9 is 24.0 mm. The position size of the through hole 10 on the second square dielectric substrate 8 is the same as that Similarly, the square dielectric substrate 8 has a through hole 13 with a radius R3 of 6.0 mm, and the geometric center of the through hole 13 is 30.6 mm from the geometric center of the second square dielectric substrate 8 .

The side length w4 of the bottom reflector of the metal reflective back cavity 12 is 227.0 mm, the distance h3 from the square dielectric substrate 2 is 61.0 mm, the height h4 of the side metal wall is 83.5 mm, and the bottom of the metal reflective back cavity 12 has a through hole 14 , the radius R4 is 6.0mm, and the distance from the geometric center is 30.6mm. The structure is shown in Figures 1, 2, 3 and 4. The specific performance of the present invention is shown in Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11 and Fig. 12, and the comparison results are consistent with the description of the beneficial effects.

Claims (1)

1. A low-profile planar dipole antenna suitable for 4G LTE communication, comprising a planar dipole antenna, a frequency-selective surface reflector and a metal reflection back cavity, characterized in that: the planar dipole antenna includes a circular Shaped metal coupling patch, No. 1 square dielectric substrate, microstrip transmission line, cylindrical metal post, SMA connector and two elliptical metal patches; the two elliptical metal patches are closely attached to No. 1 square dielectric substrate The lower surface, and the two oval metal patches are not connected to each other; the upper surface of the No. 1 square dielectric substrate is closely attached to a circular metal coupling patch, and the radial connection of the circular metal coupling patch is connected to one end of the microstrip transmission line, and the microstrip transmission line The other end is connected to a cylindrical metal post, and the cylindrical metal post passes through the No. 1 square dielectric substrate and an oval metal patch to connect to the SMA connector; the frequency-selective surface reflector includes the No. 2 square dielectric substrate and several metal patches The metal patches are periodically arranged on the upper surface of the No. 2 square dielectric substrate at equal intervals. The No. 2 square dielectric substrate has a through hole at the position facing the SMA connector, and the through hole is not covered by the metal patch; the metal reflection The back cavity includes a bottom reflector and a side metal plate. The bottom reflector has a through hole facing the SMA connector; the side metal plate surrounds the upper surface of the bottom reflector, a planar dipole antenna and a frequency selective surface. The reflector is fixed in the space enclosed by the bottom reflector and the side metal plate, and the geometric center of the planar dipole antenna and the frequency-selective surface reflector is projected on the geometric center of the bottom reflector.