Research And Design Of Omnidirectional High Horizontal Gain Antenna

As an essential electromagnetic transceiver in radio equipment,antenna is the focus of research in radio field.Omnidirectional antenna is widely used in mobile communication,vehicle communication,space vehicle and other fields because of its characteristics of uniform radiation in the horizontal direction.At present,with the rapid development of communication technology,high gain and miniaturization are required for omnidirectional antenna.By compressing the beam width of the vertical plane of the omnidirectional antenna,the antenna beam coverage will be enlarged,and the antenna gain will also be improved.This paper mainly studies the method of improving the horizontal gain of omnidirectional antenna,and finally obtains the omnidirectional antenna with narrow half power beam width（HPBW）and high horizontal gain.The specific content of this essay is as follows:1.In this paper,an epsilon-negative（ENG）metamaterial structure was designed,which consists of four U-shaped bands and two cross shaped bands.By placing a metamaterial array above the omnidirectional antenna,the half power beam width on the vertical plane is compressed,and the horizontal gain of the antenna is improved.The impedance bandwidth of the antenna is 5.84-6.14GHz.The HPBW of the antenna at5.9GHz is reduced from 80°to 33°after loading the metamaterial structure.In addition,the horizontal gain of the antenna within a certain frequency range has reached 3.61 d Bi.2.In this paper,a low profile high horizontal gain omnidirectional antenna with near-zero refractive index metamaterial（NZRIM）is designed.A novel metamaterial structure is proposed.The metamaterial element consists of two symmetrical C-shaped strips and one curved strip.The metamaterial cells are centrally symmetrically distributed around the omnidirectional antenna to guide the propagation direction of the electromagnetic wave close to the horizontal direction,which improves the horizontal gain.The antenna works at 5.78-6.12GHz.After loading NZRIM,the horizontal gain of the antenna in a certain frequency range is increased by more than 0.5d B,with a peak horizontal gain of 2.68d Bi.The size of the antenna is only 2.13λ₀×2.13λ₀×0.04λ₀（λ₀is the free-space wavelength corresponding to 5.9GHz）.3.A low profile high horizontal gain omnidirectional antenna suitable for dedicated short range communication（DSRC）is designed.By loading three circular guides around the center-fed circular patch antenna,the radiation and horizontal gain of the omnidirectional antenna are effectively improved.The antenna has a working bandwidth of 5.66-6.05GHz.The size of the antenna is 2.75λ₀×2.75λ₀×0.04λ₀（λ₀is the free-space wavelength corresponding to 5.9GHz）,with minimal profile height.After loading these directors,the horizontal gain of the antenna at 5.9GHz is increased from-3.68d Bi to1.93d Bi.The antenna has the advantages of low profile,high horizontal gain,and complete ground plane.