Artificial surface plasmon polariton based planar millimeter wave high-gain dual-beam antenna
Technical Field
The invention relates to a high-gain dual-beam antenna based on an artificial surface plasmon polariton plane millimeter wave, and belongs to the technical field of wireless communication.
Background
With the rapid development of communication services, the number of users and the flow rate increase rapidly, in order to reduce the occurrence of low rate conditions caused by high network load, the information capacity of a hot spot region needs to be increased, and in order to achieve the purpose of capacity expansion on a base station, a dual-beam antenna can be adopted to increase the channel capacity. The traditional dual-beam antenna can be applied to base station antennas and vehicle-mounted radar detection, and can realize a multi-directional detection function under the condition of not adjusting the azimuth of the antenna. There are a number of disadvantages:
1. conventional dual beam antennas, their gain is not high;
2. meanwhile, the dual-beam antennas adopt a dual-feed mode, and one port corresponds to one beam, so that the complexity of a feed network is increased.
The traveling wave long conductor antenna has the bifurcate symmetrical effect of dual beams naturally, and is suitable for the design of dual-beam antennas. The traveling wave long wire loaded based on the SSPPs structure utilizes the slow wave effect of SPPs waves, so that the volume of the antenna can be effectively reduced; meanwhile, the SPPs wave has strong binding property. Therefore, the inventors conceived that the transmission and radiation of the surface wave can be controlled by adjusting the depth of the slot, thereby increasing the gain of the antenna.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a high-gain dual-beam antenna based on artificial surface plasmon polariton planar millimeter waves, which is based on the radiation principle of a traveling-wave long-wire antenna and realizes the design goal of low profile by improving the gain of the antenna and reducing the size of the antenna by loading an SSPPs structure.
The common travelling-wave long-wire antenna is an antenna formed by wires which are longer than one wavelength and on which current is distributed according to travelling waves, and the amplitudes of the currents on the wires are equal and the phases are continuously lagged.
The directional diagram shows the following characteristics: 1. no radiation is generated in the axial direction; 2. as the length of the wire increases, the maximum radiation direction of the wire gradually approaches the axis; 3. when the ratio of the length of the wire to the wavelength is large, the main lobe direction has small change along with the ratio and has broadband characteristics.
The invention provides a high-gain dual-beam antenna based on an artificial surface plasmon polariton plane millimeter wave, which comprises a coplanar waveguide formed by a dielectric substrate, a top layer transmission line and a top layer grounding band, and is characterized in that: the top layer grounding belt is connected with a metal comb line used for inhibiting backward transmission of electromagnetic waves and improving gain, the upper surface of the dielectric substrate is further provided with an artificial surface plasmon dual-beam antenna connected with the top layer transmission line, and the artificial surface plasmon dual-beam antenna is provided with a symmetrical dentate structure.
Furthermore, the artificial surface plasmon dual-beam antenna is provided with a uniform area close to the top transmission line and a gradual change area far away from the top transmission line, the tooth length and the tooth groove depth of the uniform area are equal, and the tooth length and the tooth groove depth of the gradual change area are gradually reduced in the antenna radiation direction.
Furthermore, the top layer grounding strap is rectangular, and the metal strip is arranged on the upper surface of the dielectric substrate and arranged towards the radiation direction of the antenna.
It can be seen that, compared with a general traveling-wave long-conductor antenna, the invention performs the following improvements on the basis:
1. the loading of the planar SSPPs slot-type structure enhances the binding property of the SPPs surface waves, so that the transmission or radiation of the surface waves can be regulated and controlled to improve the gain of the antenna, and the highest gain of 15.3dBi is obtained;
2. the planar antenna structure not only realizes the design target of a low profile, but also converts the traditional long-wire antenna into a dual-beam antenna, and further realizes the improvement of the gain in the target direction;
3. the stable radiation effect of the dual-beam in a wider frequency band (22.75 GHz-25.7 GHz) is realized, and the antenna can be applied to the aspects of base station antennas, vehicle-mounted radar detection and the like.
The invention relates to a high-gain dual-beam antenna based on an artificial surface plasmon polariton plane millimeter wave, which has the following beneficial effects:
1. the loading of the planar SSPPs slot type structure enhances the binding performance of the surface waves of SPPs, the binding capacity of the planar SSPPs radiation structure in the antenna is reduced along with the reduction of the depth of the slot, and the electromagnetic waves are switched from a transmission mode to a radiation mode, so that the transmission or radiation of the surface waves can be regulated and controlled to improve the gain of the antenna, and the highest gain of 15.3dBi is obtained;
2. the stable radiation effect of the dual-beam in a wider frequency band (22.85 GHz-25.7 GHz) is realized, and the method can be applied to the aspects of base station antennas, vehicle-mounted radar detection and the like.
Drawings
The invention will be further described with reference to the accompanying drawings.
Fig. 1 is a three-dimensional structural view of an antenna of the present invention.
Fig. 2 is a top view of the antenna of the present invention.
FIG. 3 is S of the antenna of the present invention11Graph is shown.
Fig. 4(a) is an E-plane radiation pattern of the inventive antenna at 23.7 GHz.
Fig. 4(b) is the H-plane radiation pattern of the inventive antenna at 23.7 GHz.
Fig. 5(a) is an E-plane radiation pattern of the inventive antenna at 24.7 GHz.
Fig. 5(b) is an H-plane radiation pattern of the antenna of the present invention at 24.7 GHz.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
As shown in fig. 1, the present embodiment is based on an artificial surface plasmon planar millimeter wave high gain dual-beam antenna, and includes a dielectric substrate 2 (thickness of Roger RO4003c is 0.508 mm), a top transmission line 1, a top ground strip 11, a bottom ground strip 3 (thickness of metal is 0.035 mm), a comb line 12, and an artificial surface plasmon dual-beam antenna 13. The antenna is a single-layer plate structure, the antenna is symmetrical left and right along the x axis,
the dielectric substrate 2, the top transmission line 1, the top grounding strip 11 and the bottom grounding strip 3 form a coplanar waveguide. Of course, if the underlying ground strip 3 is omitted, the coplanar waveguide structure still holds, but is difficult to connect to the millimeter wave port. The embodiment with the bottom grounding strap 3 is the best mode. The bottom layer grounding strip 3 and the top layer grounding strip 11 are superposed in projection on the dielectric substrate 2, and the bottom layer grounding strip 3 and the top layer grounding strip 11 are electrically connected through a metalized through hole 14. As a complete antenna, it is also provided with a coaxial signal input port, the inner conductor of which is electrically connected to the top transmission line 1, and the outer conductor of which is electrically connected to the top ground strip 11.
As shown in fig. 1, a comb line 12 is connected to the top ground strip 11, and is useful for suppressing backward transmission of electromagnetic waves and increasing gain. The top-layer grounding strip 11 is rectangular, and the metal comb-shaped lines 12 are arranged on the upper surface of the dielectric substrate 2 and face the x direction (antenna radiation direction). Compared with the traditional scheme, the antenna cancels a gradual change structure, and has more compact size.
In this example, the artificial surface plasmon dual beam antenna 13 is disposed on the upper surface of the dielectric substrate 2 and connected to the top transmission line 1, and correspondingly, the artificial surface plasmon dual beam antenna 13 has a symmetrical tooth-shaped structure. In this embodiment, the artificial surface plasmon dual beam antenna 13 has an even region close to the top transmission line 1 and a gradient region far from the top transmission line 1, the tooth length and the tooth groove depth of the even region are equal, and the tooth length and the tooth groove depth of the gradient region are gradually reduced in the antenna radiation direction.
Compared with other antennas based on artificial surface plasmon polariton, the antenna has the advantages that the miniaturization of the antenna is realized by omitting the transition region, and the length of the antenna can be greatly reduced. The optimization of the transition region is that the SSPPs structure does not need the transition of the gradual change of the tooth sockets, and meanwhile, the tooth socket arrays are used for replacing the SSPPs structure on two sides, and meanwhile, the backward radiation of the antenna can be prevented, so that the gain is improved.
The transmission region of the antenna transmits SPPs waves (uniform region of the artificial surface plasmon dual beam antenna 13), which can reduce transmission loss, and thus can improve the gain of the antenna; the main radiation region is in a gradual change region of the SSPPs structure (gradual change region of the artificial surface plasmon dual-beam antenna 13), the depth of a tooth groove of the main radiation region is gradually reduced, the capability of binding electromagnetic waves is gradually reduced, and therefore the electromagnetic waves are converted into a radiation mode from transmission.
Specific parameters of the antenna of this embodiment are given in table 1.
TABLE 1 detailed dimensions of the antenna
Parameter(s)
|
L
|
W
|
Wstart
|
Wend
|
Lspp
|
g1 |
g2 |
P
1
|
P
2
|
Z
1
|
L
1
|
Value/mm
|
103.4
|
45
|
12.6
|
6.6
|
66.6
|
0.9
|
0.5
|
1.8
|
0.5
|
2.2
|
26.1
|
Parameter(s)
|
L
2
|
g
3
|
S
1
|
S
2
|
S
3
|
|
|
|
|
|
|
Value/mm
|
40.5
|
0.9
|
5.2
|
5
|
2.2
|
|
|
|
|
|
|
As shown in Table 2, the dual-beam direction of the antenna does not change with frequency, the gain is higher, and the beam width is stable. TABLE 23 dB beamwidth, beamdirection and gain of the antenna
frequency/GHz
|
3dB beam width/°
|
Beam direction/° c
|
gain/dBi
|
23.2
|
11
|
9/-9
|
13.7
|
23.4
|
10.7
|
9/-9
|
14.1
|
23.6
|
10.5
|
9/-9
|
14.4
|
23.8
|
10.3
|
9/-9
|
14.8
|
24
|
10.1
|
9/-9
|
15.1
|
24.2
|
9.9
|
9/-9
|
15.4
|
24.4
|
9.7
|
9/-9
|
15.6
|
24.6
|
9.6
|
9/-9
|
15.6
|
24.8
|
9.5
|
9/-9
|
15.6
|
25
|
9.4
|
9/-9
|
15.5
|
25.2
|
9.5
|
8/-8
|
14.9
|
25.4
|
9.7
|
9/-9
|
14
|
25.6
|
10.5
|
9/-9
|
12.8 |
The impedance bandwidth of the antenna is 22.75-25.8GHz, the gain bandwidth is 22.7-25.7GHz, and therefore the working bandwidth of the antenna is 22.75-25.7 GHz. The gain of the in-band antenna is stable. Fig. 4 shows an E-plane (Theta =0 °) pattern and an H-plane (phi =9 °) pattern of the antenna at 23.7 GHz. Fig. 5 shows an E-plane (Theta =0 °) pattern and an H-plane (phi =9 °) pattern of the antenna at 24.7 GHz. The two beam direction angles in the figure are +9 degrees and-9 degrees, the side lobe is lower, the 3dB beam width is narrow, and the main beam is concentrated. Meanwhile, with the change of the frequency, the directional diagram is stable.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.