Research On Ka-band Omnidirectional Array Of Antenna Technology

With the increasing demand for high data rates in the communications industry,it is generally desired that omnidirectional antennas have the characteristics of high gain and wide bandwidth.Waveguide slot antennas are widely used in many fields where high-gain antennas need to be designed,such as radar,remote sensing,aerospace and so on,due to the characteristics of large power capacity,low loss,achieving high efficiency and high gain easily.However,the bandwidth of waveguide slot antenna is generally narrow though whose bandwidth can be broadened by band broadening technology.In recent years,dielectric antennas have received widespread attention due to the characteristics that they may achieve high gain and wide bandwidth simultaneously.Therefore,this paper demonstrates two metal waveguide slot omnidirectional antennas and a dielectric waveguide omnidirectional antenna.The main content of this article is as follows:1.Design of a narrow band metal waveguide omnidirectional antenna.When the slot spacing is not the half of waveguide wavelength,the antenna is easy to obtain a small standing wave coefficient.Based on this principle,a rectangular waveguide slot antenna with a mixture of resonant and non-resonant array is designed.The antenna forms an omnidirectional and high-gain pattern by slitting the up and down surfaces of rectangular waveguide.And the antenna resonates at the center frequency and obtains a good S11value when designed as a hybrid array thai is part of the slot spacing is?_g/2 and the other is greater than?_g/2.It can be seen from the simulation and measurement results that the antenna gain reaches 10d B and the S11 value is-27d B at the center frequency.Compared with the antenna using the resonant array design method,the antenna using the hybrid array design method can achieve better impedance matching without additional impedance structures at the input or output end.This method reduces the workload of simulating and debugging the antenna and makes the antenna a simple structure.Then,another waveguide slot omnidirectional antenna with enhanced bandwidth is designed.This scheme utilizes broadband impedance matching technology that the height of different metal pillars in the waveguide is equivalent to the corresponding reactance value.A metal pillar added to the center line of the wide surface of feed waveguide makes the antenna generate two resonance points.Thus,the bandwidth is enhanced.Finally,the bandwidth of the antenna is expanded by 118MHz when S11<-10d B,and the bandwidth is expanded by 224MHz when S11<-15d B.Compared with an antenna in which metal posts of different lengths are used at multiple positions to make the antenna generate a resonance point,the antenna has a simple structure and is easy to manufacture.2.Design of a broad band high-gain omnidirectional antenna based on dielectric waveguide.When the periodic structures are loaded on the surface of the dielectric waveguide,the pattern is closed to the normal direction of the dielectric waveguide axis.Based on this and the principle of periodic leaky wave antenna,an omnidirectional and high gain antenna is realized by loading multiple metal rings on the dielectric circular waveguide.Finally,the antenna's gain reaches 10d B,and its efficiency is 88%.And S11<-10d B in the entire simulation frequency band.The length of the antenna is about10mm smaller than the length of the antenna whose metal rings are embedded in the dielectric waveguide.