CN112310630A

CN112310630A - Wide-band high-gain printed antenna

Info

Publication number: CN112310630A
Application number: CN202011221799.9A
Authority: CN
Inventors: 黄丘林; 黄佳祁; 史小卫
Original assignee: Xidian University
Current assignee: Xidian University
Priority date: 2020-11-05
Filing date: 2020-11-05
Publication date: 2021-02-02

Abstract

The invention discloses a broadband high-gain printed antenna, which mainly solves the problem of low gain of the existing printed antenna and comprises two dielectric substrates (1), wherein a radiation unit (2) and a microstrip feed balun structure (3) are respectively printed on two sides of each dielectric substrate, and the two dielectric substrates (1) are arranged in a cross manner. Antenna radiating element (2) comprise a pair of L shape radiation array (5), 1/8 wavelength departments are equipped with directly over should to L shape radiation array and lead to array (4), in order to improve the input impedance matching of antenna, gain is improved, should lead to and open in the middle of array (4) and have isolation tank (7), and isolation tank opposite direction on two dielectric slabs, lead to the electrical contact between array (4) when avoiding two dielectric substrate (1) quadrature installation. The invention obviously improves the input impedance matching and the radiation efficiency of the antenna, improves the gain of the antenna and can be used for wireless communication equipment.

Description

Wide-band high-gain printed antenna

Technical Field

The invention belongs to the technical field of antennas, and particularly relates to a broadband high-gain printed antenna which can be used for wireless communication equipment.

Background

With the development of wireless communication technology, the index requirements for base station antennas are also higher and higher. Modern wireless communication systems require that base station antennas have the characteristics of wide frequency band, high gain, dual polarization, miniaturization and the like, and also require that the antennas are easy to process and install, and the electrical performance is better after the antenna arrays are formed. The traditional antenna structures such as dipole antennas and yagi antennas have the defects of large size and the like, so that the development of base station antennas is hindered. Printed antennas are widely used in various wireless communication systems due to their small size, light weight, ease of integration, and conformability to carriers. However, the existing printed antenna also has the disadvantages of relatively narrow bandwidth, large loss, low gain and the like.

Many experts and scholars at home and abroad have made many studies on changing the feed structure in order to increase the bandwidth of the printed dipole antenna. Bo Pan et al in its "Equivalent-Circuit Analysis of a Broadband and Printed polarized With Adjusted impedance and an Array for Base Station Applications" (IEEE Transactions on Antennas and Propagation.) adopt a mode of directly adopting a 50 ohm microstrip impedance line to feed from the lower end of the antenna, overcoming the difficulty of impedance matching from the upper end of the antenna, but its VSWR ≦ 2 impedance matching bandwidth is only 40%. Patent CN103531895B published in 2017 discloses a novel broadband printed dipole antenna with branch line integrated feed balun, which includes an SMA joint, a dielectric plate, a radiating element, and a microstrip line feed integrated balun. The radiation unit and the microstrip line integrated balun are respectively and correspondingly printed on the front side and the back side of the dielectric plate and respectively correspond to the exterior of the SMA connector and the inner core for welding for feeding. The invention adopts a mode of adding branch lines in the center of the L-shaped microstrip feed, which is equivalent to series resistance, improves the impedance matching of the antenna, expands the bandwidth, and realizes the broadband characteristic, wherein the bandwidth with VSWR less than or equal to 1.5 is not less than 50%. However, this structure increases the bandwidth, but increases the loss due to the use of the series resistance, and significantly reduces the maximum gain to less than 5.5 dBi.

Disclosure of Invention

The present invention is directed to a printed antenna with wide frequency band and high gain, which is provided to improve the gain of the antenna while ensuring the wide frequency band.

In order to achieve the purpose, the invention adopts the following technical scheme.

1. A broadband high-gain printed antenna comprises two dielectric substrates, wherein a radiation unit and a microstrip feed balun structure are respectively printed on two surfaces of each dielectric substrate; the method is characterized in that:

the upper end of the radiation unit is provided with a guide array to improve the input impedance matching of the antenna and improve the gain;

an isolation groove is formed in the middle of the guide array, the directions of the isolation grooves on the two dielectric plates are opposite, and therefore electric contact between the guide arrays when the two dielectric substrates are installed in an orthogonal mode is avoided.

Further, the antenna radiation unit is composed of a pair of L-shaped radiation arrays; the director array is located at a wavelength of 1/8 directly above a pair of L-shaped radiating arrays.

Furthermore, an installation groove is formed in the middle of each dielectric substrate, and the two dielectric substrates are opposite in slotting direction and used for cross and orthogonal installation of the two dielectric substrates.

Furthermore, the pair of L-shaped radiating arrays have the same structure and are in mirror symmetry in the vertical direction.

Further, the microstrip feed balun structure comprises a feed port connected with the SMA connector, a 50 ohm impedance line, an impedance matching transformation section and an open-circuit stub.

Furthermore, the middle part of the microstrip feed balun structure is bent, and the bending directions of the microstrip feed balun structures on the two dielectric substrates are opposite, so that the microstrip feed balun structure is prevented from being electrically contacted when the two dielectric substrates are orthogonally installed.

Furthermore, the medium substrate is an FR4 medium plate with the relative dielectric constant of 2-4.4 and the thickness of 0.7-0.8 mm.

Compared with the prior art, the invention has the advantages that the guide array is additionally arranged at the 1/8 wavelength position right above the radiation array, the resistance of the antenna is changed, the input impedance matching of the antenna is improved, the radiation efficiency of the antenna is improved, the loss is reduced, the directivity is enhanced, the half-power beam width is narrowed, and the maximum gain of the antenna is improved.

Drawings

FIG. 1 is a schematic perspective view of the present invention;

FIG. 2 is a schematic view of a radiation unit according to the present invention;

FIG. 3 is a schematic diagram of a feed microstrip feed balun structure according to the present invention;

FIG. 4 is a simulated value-frequency curve of S parameter in example 1 of the present invention;

FIG. 5 is an E-plane simulation directional diagram at different frequency points in embodiment 1 of the present invention;

fig. 6 is a maximum gain simulation value-frequency curve diagram in embodiment 1 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited to these examples.

Example 1

Referring to fig. 1, the present embodiment includes two dielectric substrates 1, a radiating element 2, a microstrip feed balun structure 3 and a director array 4. FR4 dielectric board with dielectric constant of 3, thickness of 0.762mm, height of 40mm and width of 51mm is selected for each dielectric substrate 1. The radiating element 2 and the microstrip feed balun structure 3 are respectively printed on two sides of the same dielectric substrate, and the leading array 4 is positioned right above the radiating element. The middle of each dielectric substrate is provided with a mounting groove 6 with the width of 0.9mm, and the directions are opposite. The two dielectric substrates are vertically erected on the ground in a cross manner.

Referring to fig. 2, the radiation unit 2 is composed of a pair of L-shaped radiation arrays 5 with the same structure, and the two L-shaped radiation arrays are both 1/4 wavelengths in length and half wavelengths in height, and are mirror-symmetrical in the vertical direction. The directing array 4 is located 1/8 wavelength positions directly over the L-shaped radiation array, the width is 2mm, the length is half wavelength, an isolation groove 7 with the width of 0.8mm is arranged between the directing array 4 and the L-shaped radiation array, the directions of the isolation grooves 7 on the two dielectric substrates are opposite, and the directing array is used for avoiding electrical contact between the directing array when the two dielectric substrates are orthogonally installed.

Referring to fig. 3, the microstrip feeding balun structure 3 includes a feeding port 31, a 50-ohm impedance line 32, an impedance matching transformation section 33 and an open stub 34, wherein the middle portion of the impedance matching transformation section 33 is bent, and the bending directions of the impedance matching transformation sections 33 on the two dielectric substrates are opposite to each other, so as to avoid electrical contact between the feeding structures when the two dielectric substrates are orthogonally mounted. The feed port 31 is located at the lower right of the dielectric substrate. The 50 ohm impedance line 32 is 1/4 wavelengths high and is located directly above the feed port 31. The impedance matching transformation section 33 is located right above the 50 ohm impedance line 32, and both sides thereof are connected to the open stub 34 and the 50 ohm impedance line 32, respectively. The open stub 34 is located below the impedance matching transformation section 33 and is parallel to the 50 ohm impedance line 32.

When the antenna works, the inner core of the SMA joint is connected with the microstrip feed balun structure 3, and the outer core is connected with the radiation unit 2. When feeding, the current on the microstrip feeding balun structure 3 is conducted to the radiation unit 2 through the dielectric substrate 1 and excites the radiation unit 2 to generate an electromagnetic field. The electromagnetic field generated by the radiating element 2 in turn excites the upper director element 4, causing it to generate another electromagnetic field. The two electromagnetic fields overlap and interfere with each other, thereby changing the internal impedance of the antenna.

Example 2

Referring to fig. 1, 2, and 3, the structure of the present embodiment is basically the same as that of embodiment 1. The difference is that each dielectric substrate 1 is made of FR4 dielectric board with dielectric constant of 2 and thickness of 0.7 mm; the width of the mounting groove 6 in the middle of the medium substrate is 0.8 mm; the width of the guiding array 4 is 1.5mm, and the width of the isolation groove 7 arranged in the middle of the guiding array is 1 mm.

Example 3

Referring to fig. 1, 2, and 3, the structure of the present embodiment is basically the same as that of embodiment 1. The difference is that each dielectric substrate 1 is made of FR4 dielectric board with dielectric constant of 4.4 and thickness of 0.8 mm; the width of the mounting groove 6 in the middle of the medium substrate is 0.9 mm; the width of the guiding array 4 is 2mm, and the width of the separation groove 7 arranged in the middle of the guiding array is 1.2 mm.

The effects of the present invention can be further illustrated by the following simulation experiments.

Simulation 1, the S parameter of embodiment 1 of the present invention was simulated by simulation software, and the result is shown in fig. 4. As can be seen from FIG. 4, in the frequency band from 2.45GHz to 3.25GHz, the return loss S11 of the port 1 and the return loss S22 of the port 2 are better than-15 dB, and the isolation S21 between the port 1 and the port 2 is better than-30 dB.

Simulation 2, simulating the E-plane direction diagram of embodiment 1 of the present invention with simulation software at different frequency points, and the result is shown in fig. 5, where:

FIG. 5a is an E-plane simulation directional diagram at a frequency point of 2.5GHz in accordance with embodiment 1 of the present invention;

FIG. 5b is the E-plane simulated pattern at the 2.8GHz frequency point in example 1 of the present invention;

fig. 5c is an E-plane simulation pattern at the frequency point of 3.2GHz in the embodiment 1 of the present invention.

As can be seen from fig. 5, the broadband high-gain antenna provided by the embodiment of the invention has good radiation characteristics.

Simulation 3, the maximum gain of the embodiment 1 of the present invention was simulated using simulation software, and the result is shown in fig. 6. As can be seen from FIG. 6, in the embodiment 1 of the present invention, the maximum gain is in the range of 8.0dBi to 9.4dBi within the frequency band of 2.45GHz to 3.25GHz, which is 2 dBi to 4dBi higher than that of the existing broadband printed dipole antenna.

In summary, the broadband high-gain printed antenna of the present invention realizes the characteristics of broadband and high gain, and realizes good radiation characteristics.

Claims

1. A broadband high-gain printed antenna, comprising two dielectric substrates (1), each of which is printed with a radiating element (2) and a microstrip feeding balun structure (3) on both sides; it is characterized in that:

The upper end of the radiation unit (2) is provided with a guide element (4) to improve the input impedance matching of the antenna and increase the gain;

The guiding element (4) is provided with an isolation groove (7) in the middle, and the isolation grooves on the two dielectric boards are in opposite directions, so as to prevent the two dielectric substrates (1) from being guided between the elements (4) when they are installed orthogonally. electrical contact.

2. The antenna according to claim 1, characterized in that: the antenna radiating element (2) is composed of a pair of L-shaped radiation elements (5); 1/8 wavelength above.

3. The antenna according to claim 1, characterized in that: a mounting slot (6) is provided in the middle of each dielectric substrate (1), and the two dielectric substrates are slotted in opposite directions for connecting the two dielectric substrates (1). 1) Perform a cross-orthogonal installation.

4. The antenna according to claim 1, characterized in that: a pair of L-shaped radiation elements (5) have the same structure and are mirror-symmetrical in the vertical direction.

5. The antenna according to claim 1, characterized in that: the microstrip feeding balun structure (3) comprises a feeding port (31) connected with the SMA connector, a 50 ohm impedance line (32), an impedance matching transformation section (33) and an open stub (34).

6. The antenna according to claim 1, characterized in that: the middle part of the microstrip feeding balun structure (3) is curved, and the bending directions of the microstrip feeding balun structure on the two dielectric substrates are opposite to avoid two Electrical contact between microstrip feeding balun structures (3) when the bulk dielectric substrates (1) are mounted orthogonally.

7. The antenna according to claim 1, characterized in that: the dielectric substrate (1) adopts a FR4 dielectric plate with a relative dielectric constant of 2 to 4.4 and a thickness of 0.7 to 0.8 mm.

8. The antenna according to claim 1, wherein:

The length of the guide element (4) is 1/2 wavelength, and the width is 1-2 mm.

9. The antenna according to claim 1, wherein:

The length of the L-shaped radiation element (5) is 1/4 wavelength, and the height is half wavelength;

The height of the 50-ohm impedance line (32) is 1/4 wavelength.

10. The antenna according to claim 1, wherein:

The width of the installation groove (6) is 0.8-0.9 mm;

The width of the isolation groove (7) is 0.8-1.2 mm.