CN218677564U

CN218677564U - Single-frequency band and dual-frequency band reconfigurable microstrip quasi-yagi antenna

Info

Publication number: CN218677564U
Application number: CN202223239328.8U
Authority: CN
Inventors: 周扬; 苗尧飞; 杨博; 巩执欢; 宋光伟; 吴迪; 于猛
Original assignee: Tianjin Optical Electrical Communication Technology Co Ltd
Current assignee: Tianjin Optical Electrical Communication Technology Co Ltd
Priority date: 2022-11-28
Filing date: 2022-11-28
Publication date: 2023-03-21
Anticipated expiration: 2032-11-28

Abstract

The invention discloses a single-band and dual-band reconfigurable microstrip quasi-yagi antenna, which comprises a dielectric substrate, a coplanar radiation patch, a first director, a second director, a microstrip feeder line and four radio frequency PIN diodes. Coplanar radiation patches are printed on the front surface of the dielectric substrate, radio frequency PIN diodes are respectively arranged between the first director and the second director, and between the main radiation patch and the four parasitic radiation patches of the coplanar radiation patches, and microstrip feeder lines are printed on the back surface of the dielectric substrate. By reasonably setting the on and off of the four PIN diodes, the dual-band antenna can work in an n78 frequency band or an n79 frequency band, and can also work as a dual-band antenna to work in the n78 frequency band and the n79 frequency band simultaneously. The antenna realizes good directional radiation in the working frequency band, has stable radiation performance, and is a directional antenna with novel structure, small size, light weight, low profile and small scattering section.

Description

Single-frequency band and dual-frequency band reconfigurable microstrip quasi-yagi antenna

Technical Field

The invention belongs to the technical field of wireless communication, and particularly relates to a single-band and dual-band reconfigurable microstrip quasi-yagi antenna.

Background

With the technical change and rapid popularization of 5G communication, 5G communication gradually becomes a mainstream communication technology, as a lead enterprise of the commercial communication industry in china, four operators of china mobile, china telecommunication, china unicom and china radio and television follow up with technical wave and actively develop 5G layout, 5G coverage in key areas has been completed in multiple cities, and in 5G spectrum allocation of the four operators in china, the technology applies mature n78 (3.3-3.8 GHz) and n79 (4.4-5.0 GHz) as 5G frequency bands of key deployment (wherein, china mobile has a frequency band of 4.8-4.9GHz, china telecommunication has a frequency band of 3.4-3.5GHz, china unicom has a frequency band of 3.5-3.6GHz, china radio and television has a frequency band of 4.9-5.0GHz, and china unicom, china unicom and radio and television use the frequency band of 3.3-3.4GHz together).

As an indispensable key component in 5G communication, the performance of an antenna determines the excellence of a communication system to a certain extent, and a single antenna cannot meet the use requirement of a multifunctional communication device in a communication occasion with multiple frequency bands of n78 and n79, however, if a multi-antenna design is adopted, the load bearing burden and the production and manufacturing cost of the communication device are increased, space resources are wasted, meanwhile, if the electromagnetic compatibility problem among the antennas is not considered, the communication quality is greatly reduced, and in order to avoid the above disadvantages, the realization of tunable resonance frequency multiplexing on a single antenna has become a current research focus. The microstrip quasi-yagi antenna, as a classical directional antenna, combines the advantages of the microstrip antenna and the yagi antenna, has the advantages of high gain, good directional radiation characteristic, light weight, low profile, small scattering cross section and the like, and is widely applied to the fields of satellite communication, spectrum environment detection, weapon fuze and the like. The frequency reconfigurable technology and the microstrip quasi-yagi antenna technology are combined, the resonant frequency of the antenna can be reconfigured in real time according to actual needs in a 5G communication environment, and high-gain directional characteristics are met, but the frequency reconfigurable microstrip quasi-yagi antenna which is combined with the two technologies and applied to a 5G frequency band is few at present, in the existing research, for example, in the article of 'a frequency reconfigurable end-fire antenna applied to 5G-FR 1' issued by researchers such as business pioneers and the like, a reconfigurable end-fire antenna with the central resonant frequency of 3.5GHz or 4.9GHz is provided, the design totally utilizes 10 switches to realize frequency switching, the frequency switching function is complex to realize, the frequency modulation mode is few, a plurality of switch control circuits are needed, and the manufacturing difficulty is high. In the patent application with the application publication number of CN107785671A and the name of 'a frequency reconfigurable microstrip patch yagi antenna and a reconfiguration method', a frequency reconfigurable microstrip patch antenna with the center tuning frequency from 14.2GHz to 13.15GHz is provided, the antenna adopts a three-layer structure, frequency reconfiguration is realized by using a liquid crystal material, the cost is high, a complex frequency modulation means can be influenced by a plurality of parameters, the radiation gain of the antenna is low, and the frequency reconfiguration difficulty in practical application is high.

Disclosure of Invention

In view of the above, the invention provides a single/dual band reconfigurable microstrip quasi-yagi antenna applied to 5G communication n78 and n79 frequency bands, which combines a frequency reconfigurable technology and a microstrip quasi-yagi antenna technology, so that the antenna can perform a frequency switching function in the n78 and n79 frequency bands, has good electrical properties and stable directional radiation performance, and is low in production cost, low in profile, small in scattering sectional area, simple and easy in structure, low in processing difficulty and beneficial to engineering implementation.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a single-band and dual-band reconfigurable microstrip quasi-yagi antenna is characterized in that: the antenna comprises a medium substrate, wherein a coplanar radiation patch, a first director and a second director are printed on the front surface of the medium substrate, the bottom of the coplanar radiation patch is connected with the lower edge of the front surface of the medium substrate, a first radio frequency PIN diode, a second radio frequency PIN diode, a third radio frequency PIN diode and a fourth radio frequency PIN diode are arranged on the coplanar radiation patch, a microstrip feeder is printed on the back surface of the medium substrate, and the bottom end of the microstrip feeder is connected with the lower edge of the back surface of the medium substrate.

Specifically, the main radiation patch consists of a coplanar stripline, an upper pair of rectangular double dipoles with unequal lengths, a lower pair of rectangular double dipoles and a truncated ground plane loaded with rectangular branches. According to the basic principle of the microstrip quasi-yagi antenna, the coplanar stripline is used as a main radiation patch excitation source and transmits electromagnetic energy to a double dipole. The double dipoles are used as excitation oscillators of the quasi-yagi antenna to determine the resonance frequency points of the antenna, and the design of the upper and lower pairs of unequal-length rectangular double dipoles enables the antenna to have double-frequency working characteristics in the frequency bands of n78 and n79 in 5G communication. The invention loads two extended rectangular branches symmetrically to two ends of the truncated ground plane, thereby effectively reducing the transverse size of the antenna while working as a reflector.

Furthermore, the coplanar stripline is provided with a three-step ladder-shaped gap from narrow to wide from bottom to top along the central line of the dielectric substrate, the structure works equivalently to a balun structure, and the aim of impedance transition of the coplanar stripline from the three-step ladder-shaped gap to the double dipole is fulfilled.

Further, first director and second director are as the oscillator that leads to of accurate yagi antenna, can effectively assemble in antenna end fire direction with electromagnetic energy, promote the radiation efficiency of antenna at the operating frequency channel, improve main lobe radiation direction directive property

Furthermore, the microstrip feeder has the characteristic of a broadband impedance converter, and achieves good impedance matching with a 50 omega feed source. The invention adopts a feeding mode of a microstrip line transition band coplanar stripline, can convert an unbalanced input signal into a balanced signal which can be transmitted on a double dipole by providing 180-degree phase delay, realizes the directional radiation characteristic of the yagi antenna, can improve the defect of narrower bandwidth of the traditional microstrip quasi-yagi antenna by designing a microstrip feeder structure, and effectively widens the impedance bandwidth of the antenna.

Furthermore, the loading of the parasitic radiation patch is mainly close to two pairs of unequal-length rectangular double dipoles in the main radiation patch, so that the basic structure of the microstrip quasi-yagi antenna is not changed, the directional radiation characteristic of the antenna is not influenced, and the frequency reconstruction is realized while the high-gain radiation is realized.

Furthermore, the coplanar radiation patch on the front surface of the dielectric substrate is composed of a main radiation patch and a parasitic radiation patch, a radio frequency PIN diode is arranged in a gap between the main radiation patch and the parasitic radiation patch, the radio frequency PIN diode is switched on or switched off, a distribution path of surface current of the antenna is prolonged or cut off, field distribution is changed, resonance frequency points of the antenna are influenced, and therefore frequency reconstruction is achieved.

Compared with the prior art, the single-band and dual-band reconfigurable microstrip quasi-yagi antenna has the following advantages:

the antenna provided by the invention can be flexibly switched between n78 frequency bands and n79 frequency bands, is suitable for new 5G communication frequency bands, is simple and effective in frequency switching mode and has 3 frequency switching modes, and the antenna can work in the n78 frequency band or the n79 frequency band and also can work in the n78 frequency band and the n79 frequency band as a dual-frequency antenna by reasonably setting the on and off of 4 PIN diodes.

The antenna provided by the invention realizes good impedance bandwidth of the antenna in frequency bands of n78 and n79 in 5G communication by designing unequal-length double dipoles, designing a feeding mode that a coplanar strip line loads a narrow-to-wide three-step ladder-shaped gap from bottom to top along the central line of a dielectric substrate and designing an improved microstrip line transition band coplanar strip line, and has good impedance matching degree.

The antenna has a single-layer structure, and is small in size, light in weight, low in profile and small in scattering cross section. The device can be installed on various communication equipment platforms, facilitates the modular design of the communication equipment, is not easy to generate structural interference with other communication modules, and has high engineering utilization value.

The antenna has clear working principle and novel and simple structure, can be processed and manufactured according to a conventional production mode, and can realize low-cost and high-efficiency production. The antenna has wide working frequency band, stable electrical property, small work load of material object regulation and measurement and easy engineering realization.

The antenna provided by the invention realizes good directional radiation in the working frequency band, has stable radiation performance, can be used for various devices such as frequency spectrum monitoring, signal blindness compensation, communication relay and the like, is suitable for various indoor or outdoor 5G communication occasions, and also provides a new array element thought for a design scheme of a 5G communication antenna array.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the invention without limitation. In the drawings:

fig. 1 is a front structural view of one embodiment of the inventive antenna;

fig. 2 is a back structural view of one embodiment of the inventive antenna;

fig. 3 is a return loss curve diagram of the antenna in inventive example 1;

fig. 3 (a) is a return loss curve diagram of the antenna operating in the n78 frequency band in the inventive embodiment 1 of the present invention;

fig. 3 (b) is a return loss curve diagram of the antenna operating in the n79 frequency band in the inventive embodiment 1;

fig. 3 (c) is a return loss curve diagram of the antenna in the inventive embodiment 1, which operates in n78 and n79 frequency bands;

fig. 4 is a far-field radiation pattern of 3.6GHz when the antenna operates in the n78 frequency band in the inventive embodiment 1;

FIG. 5 is a far-field radiation pattern of 4.8GHz when the antenna in inventive embodiment 1 works in the n79 frequency band;

fig. 6 is a far field radiation pattern of the antenna in inventive example 1 when operating in the dual-frequency modes of n78 and n 79;

FIG. 6 (a) is the far field radiation pattern of 3.6GHz in inventive example 1;

fig. 6 (b) is the far field radiation pattern of 4.8GHz in inventive example 1.

Description of the reference numerals

1-a dielectric substrate; 2-coplanar radiating patches; 3-a first director; 4-a second director; 5-microstrip feed line.

Detailed Description

It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings, which are merely for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be construed as limiting the invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate a number of the indicated technical features. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, the meaning of "a plurality" is two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected" and "connected" are to be construed broadly, and may be, for example, a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the creation of the present invention can be understood by those of ordinary skill in the art through specific situations.

The invention will be described in detail with reference to the following embodiments with reference to the attached drawings.

The invention creatively designs a single/double-frequency band reconfigurable microstrip quasi-yagi antenna (referred to as an antenna for short, and shown in the figure 1-2) applied to 5G communication n78 and n79 frequency bands, and the antenna comprises a dielectric substrate 1, a coplanar radiation patch 2, a first director 3, a second director 4, a microstrip feeder 5, a first radio frequency PIN diode (SW 1), a second radio frequency PIN diode (SW 2), a third radio frequency PIN diode (SW 3) and a fourth radio frequency PIN diode (SW 4), wherein the front surface of the dielectric substrate is printed with the coplanar radiation patch 2, the first director 3 and the second director 4, the bottom of the coplanar radiation patch 2 is connected with the lower edge of the front surface of the dielectric substrate 1, the coplanar radiation patch 2 is provided with the first radio frequency PIN diode (SW 1), the second radio frequency PIN diode (SW 2), the third radio frequency PIN diode (SW 3) and the fourth radio frequency PIN diode (SW 4), the reconfiguration of the working frequency of the antenna is realized by controlling the on-off of the radio frequency diodes, the back surface of the dielectric substrate is printed with the bottom end of the microstrip substrate 5 and the microstrip substrate is connected with the lower edge of the microstrip feeder.

The coplanar radiation patch 2 of the antenna comprises a main radiation patch and a parasitic radiation patch, wherein the main radiation patch consists of a coplanar stripline, an upper pair of unequal-length rectangular double dipoles and a lower pair of unequal-length rectangular double dipoles and a truncated ground plane loaded with rectangular branches, the coplanar stripline is provided with a narrow-to-wide step-shaped gap from bottom to top along the center line of a dielectric substrate, the parasitic radiation patch is divided into an upper parasitic radiation patch and a lower pair of parasitic radiation patches, the upper parasitic radiation patch consists of two rounded rectangles with the same shape and size, and the upper parasitic radiation patch is connected with the left side and the right side of the coplanar stripline of the main radiation patch through a first radio frequency PIN diode (SW 1) and a second radio frequency PIN diode (SW 2); the lower parasitic radiation patch consists of two rectangles with the same shape and size, and the left side and the right side of the lower rectangular double dipole of the main radiation patch are connected with a third radio frequency PIN diode (SW 3) and a fourth radio frequency PIN diode (SW 4). The main radiation patch and the two pairs of parasitic radiation patches are symmetrically and respectively arranged on the left side and the right side of the front surface of the dielectric substrate by the central line of the dielectric substrate 1;

the first director 3 and the second director 4 of the antenna are rectangular patches with the same shape and size, and are collinear with the center line of the coplanar radiating patch 2, the first director 3 is right above the coplanar radiating patch 2, and the second director 4 is right above the first director 3.

The microstrip feeder line 4 of the antenna is composed of a rectangular patch and an irregular round-angle opening rectangular ring, wherein the irregular round-angle opening rectangular ring is positioned above the rectangular patch and is connected with the rectangular patch.

Example 1

In the embodiment, the dielectric substrate 1 is rectangular (see fig. 1-2), the used material is a glass fiber epoxy resin copper clad laminate (FR-4), the relative dielectric constant is 4.4, and the length, width and height of the dielectric substrate 1 are 50mm × 33mm × 1.6mm (see fig. 3). The front side of the dielectric substrate 1 is printed with a coplanar radiation patch 2, a first director 3, a second director 4 and is loaded with 4 radio frequency PIN diodes (SW 1, SW2, SW3, SW 4), and the back side of the dielectric substrate 1 is printed with a microstrip feed line 5.

The coplanar radiating patch 2 is composed of a main radiating patch and a parasitic radiating patch.

The main radiation patch consists of a coplanar stripline, an upper pair of unequal-length rectangular double dipoles and a lower pair of unequal-length rectangular double dipoles and a truncated ground plane loaded with rectangular branches, wherein the size of the coplanar stripline is 31mm multiplied by 10mm, the coplanar stripline is positioned at the center line of the front surface of the dielectric substrate 1 and is 5mm away from the lower edge of the dielectric substrate 1, a narrow-to-wide stepped gap is formed in the coplanar stripline along the center line of the dielectric substrate from bottom to top, and the sizes of the gap are 14mm multiplied by 0.3mm, 3mm multiplied by 0.8mm and 14mm multiplied by 2mm respectively from bottom to top. The upper and lower pairs of rectangular double dipoles with unequal lengths are connected with the coplanar stripline and are bilaterally symmetrical about the central line of the dielectric substrate 1, the upper rectangular double dipoles are 9.5mm multiplied by 4mm in size and connected with the top of the coplanar stripline, the lower rectangular double dipoles are 7.5mm multiplied by 4mm in size and are 13mm apart from each other. The truncated ground plane has dimensions of 33mm x 5mm and is symmetrically loaded with rectangular branches having dimensions of 6mm x 0.9mm near the left and right edges of the dielectric substrate 1.

The parasitic radiation patch consists of an upper pair of radiation patches and a lower pair of radiation patches, the upper parasitic radiation patch consists of a fillet rectangular patch of 5mm multiplied by 2mm and a rectangular patch of 1mm multiplied by 0.9mm, the distance between the upper parasitic radiation patch and the lower side of the upper double dipole is 1mm, and the distance between the upper parasitic radiation patch and the left side and the right side of the coplanar stripline is 1.1mm. The lower parasitic radiation patch is a rectangular radiation patch with the size of 5.9mm multiplied by 2mm and is respectively and vertically placed at the positions of 1.1mm on the left side and the right side of the lower double dipole.

The sizes of the rectangular patches of the first director 3 and the second director 4 are both 15mm multiplied by 2.5mm, the first director 3 is over the coplanar radiation patch 2 and has a distance of 2.5mm, the second director 4 is over the first director 3 and has a distance of 3mm, and the distance from the second director 4 to the upper edge of the dielectric substrate 1 is 3.5mm.

Microstrip feeder 5 is formed by linking to each other rectangular paster and irregular fillet opening rectangular ring, and wherein the rectangular paster size is 6mm 3mm, links to each other with 1 lower limb of dielectric substrate, and the distance apart from 1 left limb of dielectric substrate is 12mm, and irregular fillet opening rectangular ring comprises the size 10mm 2mm, 8.5mm 2mm and 10mm 3 mm's rectangular paster, and the rectangular ring top is the circular arc corner cut, and its radius is 1mm and 2mm respectively.

The radio frequency PIN diode (SW 1, SW2, SW3 and SW 4) is BAR50-02V produced by England flying company, the device has low on-resistance, the working frequency is 10MHz-6GHz, the PIN inductance is 0.6nH, the on-resistance is 3 omega, the off-parallel resistance is 5k omega, the off-capacitance is 0.15pF, and the working temperature is-55-125 ℃. When the SW1, the SW2, the SW3 and the SW4 are all conducted, the working frequency range of the antenna is 3.11-4.11GHz, and the n78 frequency band can be covered; when the SW1, the SW2, the SW3 and the SW4 are all cut off, the working frequency range of the antenna is 3.97-5.01GHz, and the n79 frequency band can be covered; when the SW1 and the SW2 are switched on and the SW3 and the SW4 are switched off, the antenna is a dual-frequency antenna, the working frequency ranges are 3.10 GHz to 4.12GHz and 4.62 GHz to 5.04GHz, and the dual-frequency antenna can work in n78 frequency bands and n79 frequency bands.

Fig. 3 is a return loss (S11) graph of the antenna of this embodiment, and fig. 3 (a) shows a return loss graph of the antenna operating in the n78 frequency band, where the effective operating bandwidth is 3.11-4.11GHz; FIG. 3 (b) shows a return loss curve diagram of the antenna operating in the n79 frequency band, with an effective operating bandwidth of 3.97-5.01GHz; fig. 3 (c) shows a return loss curve diagram of the antenna operating in the n78 and n79 frequency bands, and the effective operating bandwidths are 3.10-4.12GHz and 4.62-5.04GHz, which illustrates that the antenna of the embodiment can effectively operate in the n78 and n79 frequency bands of 5G communication, has good impedance bandwidths, and realizes the frequency reconfiguration function in three states.

FIGS. 4, 5, and 6 are the corresponding directional diagrams of the antenna of this embodiment at the frequencies of 3.6GHz and 4.8GHz, respectively, where E-Plane/H-Plane refers to the electric field or the magnetic field, and it can be seen from FIG. 4 that the gain at 3.6GHz is 4.96dBi when the antenna operates in the n78 band; it can be seen from fig. 5 that when the antenna operates in the n79 band, the gain at 4.8GHz is 6.74dBi; fig. 6 (a) and 6 (b) are far field radiation patterns at 3.6GHz and 4.8GHz, respectively, and it can be seen from fig. 6 that when the antenna operates in the n78 and n79 frequency bands, the gain at 3.6GHz is 5.09dBi and the gain at 4.8GHz is 6.41dBi; the antenna radiation pattern of the embodiment shows a directional radiation state, has a good directional radiation characteristic, and under the three working states, the antenna has a good directional radiation function, stable radiation performance, good gain performance and engineering practical value.

The invention provides a single/dual-band reconfigurable microstrip quasi-yagi antenna applied to 5G communication n78 and n79 frequency bands, which is thoroughly introduced, and the invention applies specific examples to explain the principle and the implementation mode of the invention, and the description of the above embodiments is only used for helping to understand the core idea of the invention; while the invention has been described with reference to specific embodiments and applications, it will be apparent to those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A single-band and dual-band reconfigurable microstrip quasi-yagi antenna is characterized in that: the antenna comprises a dielectric substrate (1), wherein a coplanar radiation patch (2), a first director (3) and a second director (4) are printed on the front surface of the dielectric substrate, the bottom of the coplanar radiation patch (2) is connected with the lower edge of the front surface of the dielectric substrate (1), a first radio frequency PIN diode, a second radio frequency PIN diode, a third radio frequency PIN diode and a fourth radio frequency PIN diode are arranged on the coplanar radiation patch (2), a microstrip feeder (5) is printed on the back surface of the dielectric substrate, and the bottom end of the microstrip feeder (5) is connected with the lower edge of the back surface of the dielectric substrate (1).

2. The single-band and dual-band reconfigurable microstrip quasi-yagi antenna as claimed in claim 1, wherein: the coplanar radiation patch (2) comprises a main radiation patch and a parasitic radiation patch, wherein the main radiation patch comprises a coplanar stripline, an upper pair of unequal-length rectangular double dipoles and a lower pair of unequal-length rectangular double dipoles and a truncated ground plane loaded with rectangular branches, the coplanar stripline is provided with a narrow-to-wide step-shaped gap from bottom to top along the center line of the dielectric substrate, the parasitic radiation patch is divided into an upper parasitic radiation patch and a lower parasitic radiation patch, the upper parasitic radiation patch comprises two rounded rectangles with the same shape and size, and the upper parasitic radiation patch is connected with the left side and the right side of the coplanar stripline of the main radiation patch through a first radio frequency PIN diode and a second radio frequency PIN diode; the lower parasitic radiation patch comprises two rectangles with the same shape and size, the left and right sides of the lower rectangular double dipole of the main radiation patch are connected with the third radio frequency PIN diode and the fourth radio frequency PIN diode, and the main radiation patch and the two pairs of parasitic radiation patches are symmetrically arranged on the left and right sides of the front surface of the dielectric substrate respectively by the central line of the dielectric substrate (1).

3. The single-band and dual-band reconfigurable microstrip quasi-yagi antenna as claimed in claim 1, wherein: the first director (3) and the second director (4) are rectangular patches with the same shape and size, and are collinear with the center line of the coplanar radiation patch (2), the first director (3) is arranged right above the coplanar radiation patch (2), and the second director (4) is arranged right above the first director (3).

4. The single-band and dual-band reconfigurable microstrip quasi-yagi antenna as claimed in claim 1, wherein: the microstrip feeder line (5) is composed of a rectangular patch and an irregular round-angle opening rectangular ring, wherein the irregular round-angle opening rectangular ring is positioned above the rectangular patch and is connected with the rectangular patch.

5. The single-band and dual-band reconfigurable microstrip quasi-yagi antenna as claimed in claim 1, wherein: the dielectric substrate (1) is rectangular, the length, width and height dimensions are 50mm multiplied by 33mm multiplied by 1.6mm, the dielectric substrate is made of a glass fiber epoxy resin copper-clad plate, and the relative dielectric constant of the dielectric substrate is 4.4.

6. The single-band and dual-band reconfigurable microstrip quasi-yagi antenna as claimed in claim 1, wherein: the coplanar radiation patch (2), the first director (3), the second director (4) and the microstrip feeder (5) are all metal patches.