CN109980346A - A kind of high-isolation bimodulus ultra wide band mimo antenna - Google Patents

Abstract

The invention provides a high-isolation dual-mode ultra-wideband MIMO antenna. The antenna is provided with a microstrip feeder (2) made of metal copper foil, a circular coupling structure (4), A through-hole short-circuit structure (3); wherein, the coplanar waveguide feeder (1) and the radiation element (6) are connected in the middle of the antenna, and the impedance matching structure (5) is located between the coplanar waveguide feeder (1) and the radiation element (6) The microstrip feed line (2) is connected with the circular coupling structure (4), and the through-hole short-circuit structure (3) is connected with both sides of the dielectric substrate (7). The transition structure of the two antennas and the radiation patch structure are shared, which realizes a compact design; the two feed ports of the antenna have a high degree of isolation, and no additional decoupling structure is required. It is realized by ordinary single-layer PCB board technology, and the design and processing are simple. This type of antenna has high integration and high isolation, and has good application prospects in ultra-wideband communication systems.

Description

A high isolation dual-mode ultra-wideband MIMO antenna

technical field

The invention relates to a high isolation dual-mode ultra-wideband MIMO antenna radiation unit technology, and belongs to the technical field of microwave antennas.

Background technique

Ultra-wideband (UWB) communication can transmit information at a very high data rate (480Mbit/s) and low power (200μW) within a limited distance (4m), so it has the advantages of high transmission rate, wide bandwidth, The system has a series of characteristics such as large capacity, low transmission power, strong anti-interference performance, and short transmission distance.

MIMO (Multiple-Input Multiple-Output) technology refers to the use of multiple transmitting and receiving antennas at the transmitting and receiving ends, so that signals are transmitted and received through multiple antennas at the transmitting and receiving ends. MIMO technology can make full use of space resources, and can double the system channel capacity without increasing spectrum resources and antenna transmit power. And it can solve the multipath fading, reduce the bit error rate, and improve the reliability of the channel.

Although UWB technology has many advantages such as abundant spectrum resources and strong anti-interference performance, its radiation gain is small and the transmission distance is short. The combination of MIMO technology and ultra-wideband technology uses the diversity gain brought by MIMO technology to overcome the shortcomings of ultra-wideband technology, greatly improving channel capacity, and is expected to achieve long-distance transmission.

To solve the problem of mutual coupling when using an ultra-wideband MIMO antenna, a decoupling resonant structure should be added in the design, or the common ground should be slotted or deformed, which increases the difficulty of the design.

Technical problem: The purpose of the present invention is to overcome the above-mentioned deficiencies and deficiencies of the prior art, and to provide a dual-mode ultra-wideband MIMO antenna with high isolation. The antenna can generate different directional patterns of the main lobes under the feeding of port 1 and port 2, and has high isolation between the two ports. In addition, the antenna has the advantages of stable radiation state in a wide frequency working range, simple feeding method, compact structure, easy processing, small size and low cost.

Technical solution: The present invention provides a type of high isolation dual-mode ultra-wideband MIMO antenna, which is designed based on a coplanar waveguide odd-mode even-mode feed and elliptical disk antenna technologies. The coplanar waveguide even-mode feed circuit is composed of a coplanar waveguide transmission line, and the odd-mode feed structure is composed of a microstrip coupling line and a metal through-hole short circuit. There is a circular metal sheet at the end of the microstrip coupling line, which can provide Transition from stripline to odd mode in coplanar waveguide. It is realized by ordinary single-layer PCB board technology, and the design and processing are simple. This type of antenna has high integration and high isolation, and has good application prospects in ultra-wideband communication systems.

The present invention is a dual-mode ultra-wideband MIMO antenna with high isolation, which is characterized in that the antenna comprises a dielectric substrate and metal copper foils located on the upper and lower surfaces of the dielectric substrate, and a coplanar surface made of metal copper foils is arranged on the upper surface of the dielectric substrate A waveguide feeder, an impedance matching structure, and a radiation unit; a microstrip feeder made of metal copper foil, a circular coupling structure, and a through-hole short-circuit structure are arranged on the lower surface of the dielectric substrate; wherein, the coplanar waveguide feeder is connected to the radiation unit at the In the middle of the antenna, the impedance matching structure is located between the coplanar waveguide feeder and the radiating element; the microstrip feeder is connected to the circular coupling structure, and the through-hole short-circuit structure connects both sides of the dielectric substrate.

The coplanar waveguide even mode generated by the coplanar waveguide feeder port excites antenna mode 1; the coplanar waveguide odd mode generated by the microstrip feeder port excites antenna mode 2; the two modes share the same radiating element and impedance matching structure.

The circular coupling structure realizes the transition from the microstrip mode to the coplanar waveguide odd mode, reduces the radius of the circular coupling structure, and can increase the working frequency of the transition structure, thereby increasing the working frequency of the antenna.

The realization of high isolation between the coplanar waveguide feeder port and the two ports of the microstrip feeder is due to the following two reasons: (a) The high isolation of the feeding structure: the electric field of the odd mode and the even mode of the coplanar waveguide , the current directions are opposite, and the two modes cannot be coupled with each other; (b) The high isolation of the two modes of the antenna: the two radiation modes of the antenna are both eigenmodes, and the patterns generated by the two modes are orthogonal.

The metal through-hole short-circuit structure can suppress the propagation of the coplanar waveguide odd mode caused by the circular coupling structure, and the feeding mode of the coplanar waveguide feeder port is the coplanar waveguide even mode, so whether the coplanar waveguide feeder port is connected to a load or No load does not affect the reflection parameter S ₂₂ and antenna pattern of the microstrip feeder port; in the same way, whether the microstrip feeder port is connected to a load or no load does not affect the reflection parameter S ₁₁ and antenna pattern of the coplanar waveguide feeder port. .

The presence or absence of the metal through hole short-circuit structure does not affect the isolation degree between the coplanar waveguide feeder port and the microstrip feeder port of the even-mode feeding.

The direct high isolation of the antenna port is brought about by the feeding structure and the radiation properties of the antenna: the electric field and current directions of the odd mode and the even mode of the coplanar waveguide are opposite, and the two modes cannot be coupled with each other; High isolation of modes: The two radiation modes of the antenna are both eigenmodes, and the patterns generated by the two modes are orthogonal, so they cannot be coupled to each other. This high isolation is brought about by its own characteristics, so there is no need to add decoupling structures. The through-metal short-circuit structure is used to suppress the propagation of the odd mode of the coplanar waveguide generated by the microstrip coupling line to the port, and does not affect the isolation between the port of the microstrip line and the even mode port of the coplanar waveguide.

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

1. The present invention also has the feature of sharing the antenna radiation structure. In order to realize the characteristics of multiple input and output antennas, traditional MIMO antennas need to design multiple antenna structures, feed separately, and specially design decoupling structures in order to achieve high isolation. In the present invention, the radiation structures of the two antenna modes are shared, and the feeds are respectively fed by the coplanar waveguide and the microstrip.

2. The present invention has the characteristics of ultra-wideband. Both modes operate in a wide frequency band, and the radiation pattern remains stable over a wide band.

3. The present invention has the characteristics of high isolation. In the present invention, since the feeding mode is the odd mode and the even mode of the coplanar waveguide, there is orthogonality between the two modes, and there is also orthogonality between the two antenna modes. Therefore, there is a high degree of isolation between the antenna ports.

Description of drawings

Fig. 1 is the overall schematic diagram of the antenna structure of the present invention;

Fig. 2 is a kind of concrete structure reflection coefficient test result graph of the present invention;

Fig. 3 is the above-mentioned concrete structure port isolation degree test result diagram of the present invention;

Fig. 4 is the E-plane normalized power pattern measured by the above-mentioned specific structure of the present invention in the coplanar waveguide feed 1 (mode 1), and the frequencies are 5GHz, 10GHz, and 15GHz respectively;

5 is a normalized power pattern of the E-plane measured in the microstrip feed 2 (mode 2) of the above-mentioned specific structure of the present invention, and the frequencies are 5 GHz, 10 GHz, and 15 GHz, respectively.

In the figure: coplanar waveguide feeder 1 , microstrip feeder 2 , through-hole short-circuit structure 3 , circular coupling structure 4 , impedance matching structure 5 , radiation unit 6 , and dielectric substrate 7 .

Detailed ways

The present invention will be described in more detail below with reference to the accompanying drawings and embodiments.

A high-isolation dual-mode ultra-wideband MIMO antenna of the present invention, its overall structural schematic diagram is shown in Figure 1, the antenna includes a coplanar waveguide feeder 1, an impedance matching structure 5, an elliptical radiating element 6, a microstrip feeder 2, a connecting circle The coplanar waveguide feed line 1 is connected to the elliptical radiating element 6 through the impedance matching structure 5 ; and the microstrip feed line 2 feeds the radiating element 6 through the circular coupling structure 4 . The entire structure is integrally printed on the dielectric substrate 7 .

An implementation example is a high-isolation dual-mode ultra-wideband MIMO antenna.

The substrate materials used in the antenna design are all Rogers 4003C, the dielectric constant is 3.38, and the loss tangent at 10GHz is 0.0027. The substrate thickness is 0.508mm. The metal used was copper with a thickness of 0.018mm. The size of the entire antenna is about 91×67mm, and the size of the antenna can be further reduced if a high dielectric constant substrate is used.

It can be seen from the reflection coefficient test results in FIG. 2 that the coplanar waveguide feed 1 (mode 1) of the present invention can work at 2.8-20 GHz, and the microstrip feed 2 (mode 2) can work at 4.4-17.6 GHz. It can be seen from the port isolation test results in Figure 3 that the isolation between the two ports is above 15dB in the entire operating frequency band (2GHz-20GHz).

From the measured E-plane normalized power pattern of coplanar waveguide feed 1 (mode 1) in Fig. 4, it can be seen that the antenna mode 1 radiates to both sides of the antenna, while the microstrip feed 2 (mode 1) of Fig. 5 radiates to both sides of the antenna. 2) The measured E-plane normalized power pattern shows that the antenna mode 2 is forward radiation.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (6)

1. a high isolation dual-mode ultra-wideband MIMO antenna, is characterized in that this antenna comprises dielectric substrate (7) and the metal copper foil positioned at the upper and lower surfaces of dielectric substrate (7), on the upper surface of dielectric substrate (7) A coplanar waveguide feeder (1) made of metal copper foil, an impedance matching structure (5), and a radiation element (6) are provided; a microstrip feeder (1) made of metal copper foil is arranged on the lower surface of the dielectric substrate (7). 2), a circular coupling structure (4), and a through-hole short-circuit structure (3); wherein, the coplanar waveguide feeder (1) and the radiating element (6) are connected in the middle of the antenna, and the impedance matching structure (5) is located in the coplanar Between the waveguide feed line (1) and the radiation unit (6); the microstrip feed line (2) is connected with the circular coupling structure (4), and the through-hole short-circuit structure (3) is connected with both sides of the dielectric substrate (7). 2. The high-isolation dual-mode ultra-wideband MIMO antenna according to claim 1, wherein the coplanar waveguide even mode generated by the coplanar waveguide feeder (1) port excites antenna mode 1; the microstrip The odd mode of the coplanar waveguide generated at the port of the feeder (2) excites the antenna mode 2; the two modes share the same radiating element (6) and impedance matching structure (5). 3. high isolation dual-mode ultra-wideband MIMO antenna according to claim 1, is characterized in that described circular coupling structure (4) realizes the transition from microstrip mode to coplanar waveguide odd mode, reduces circular coupling structure The radius of (4) can increase the working frequency of the transition structure, thereby increasing the working frequency of the antenna. 4. high isolation dual-mode ultra-wideband MIMO antenna according to claim 1, is characterized in that the realization of high isolation between two ports of described coplanar waveguide feeder (1) port and microstrip feeder (2) is It is caused by the following two reasons: (a) the high isolation of the feeding structure: the electric field and current direction of the odd mode and the even mode of the coplanar waveguide are opposite, and the two modes cannot be coupled with each other; (b) the two modes of the antenna High isolation: The two radiation modes of the antenna are eigenmodes, and the patterns generated by the two modes are orthogonal. 5. The high-isolation dual-mode ultra-wideband MIMO antenna according to claim 1, wherein the metal through-hole short-circuit structure (3) can suppress the propagation of the coplanar waveguide odd mode generated by the circular coupling structure (4) , and the feeding mode of the coplanar waveguide feeder (1) port is the coplanar waveguide even mode, so whether the coplanar waveguide feeder (1) port is connected to a load or no load does not affect the reflection parameters of the microstrip feeder (2) port. (S ₂₂ ) and the antenna pattern; similarly, whether the port of the microstrip feeder (2) is loaded or unloaded does not affect the reflection parameter (S ₁₁ ) and the antenna pattern of the port of the coplanar waveguide feeder (1). 6. The high-isolation dual-mode ultra-wideband MIMO antenna according to claim 4, 5, characterized in that the metal through hole short-circuit structure (3), the presence or absence of which does not affect the coplanar waveguide of the even-mode feeding The degree of isolation between the feeder (1) port and the microstrip feeder (2) port.