Research On Millimeter Wave Gap Waveguide Array Antenna

In recent years,the demand for millimeter-wave（mm Wave）systems has gradually increased,and many major breakthroughs occured in the research of transmitters,receivers,millimeter-wave devices and antennas,which push the application of millimeter-wave entering a new stage of development.The increasing demand for mm Wave is due to its characteristics of wideband,good directivity,and low multipath effect.As the main component of the system,traditional transmission line includes microstrip line,strip line,waveguide,etc.Among them,microstrip line has the characteristics of small size,light weight,and stable structure,but it has great loss in the millimeter wave frequency band,which limits its applications.Meanwhile,the waveguide has low loss and high structural strength,but its fabrication needs to be processed separately and then assembled.The emergence of full-metal gap waveguide avoids energy leakage and reduces losses.Compared with traditional waveguides,it is easier to manufacture,but its size is still bulky and the fabrication is complicated.Considering the above problems,substrate integrated gap waveguide was proposed.It uses substrate instead of air gap,which has better stability.Due to its similarity to microstrip line,it provides design flexibility.In this paper,gap waveguide array antennas and substrate integrated gap waveguide transmission line are studied in the millimeter wave frequency band:1.A wideband array antenna based on hybrid feeding was studied and designed.The antenna unit uses bow-tie patch to achieve directional radiation,and the substrate integrated gap waveguide is an upside-down structure to feed the radiation patch by using two metallic vias.The feeding network is achieved by combining E-plane waveguide with substrate integrated gap waveguide.The 8×8 array antenna is finally designed and realized with the bandwidth34.6%,the maximum gain 24 d Bi,and the efficiency greater than 60%.2.An ultra-wideband full-metal planar array antenna combining ridge gap waveguide with E-plane groove gap waveguide was studied and designed at the mm Wave band.The bandwidth of the antenna unit is widened by adding double ridges to the slot and the cavity and removing the H-plane vertical metal walls.A three-stage network combining double-layer ridge gap waveguide with E-plane groove gap waveguide is designed to feed the antenna elements.Finally,an 8×8 planar array antenna is achieved,which provides an impedance matching bandwidth for|S₁₁|<-10d B being 46.8%,the maximum gain 27.7 d Bi,and the efficiency greater than 75%.3.A staggered mushroom double layer gap waveguide transmission line was proposed,and the feasibility of this structure was verified by simulation.A 3d B couplers is designed using this structure,and a lot of analysis work has been done.Their bandwidths are all greater than20%,amplitude imbalances are within 0.5d B,and the phase imbalances are within the range of±2°.Then employing this new type of transmission line,an end-fire dual-polarized antenna is designed.The bandwidth of the vertical polarized antenna is 27.2%,and the bandwidth of the horizontal polarized antenna is 23.7%.The antennas designed in this paper adopt gap waveguide,including substrate integrated gap waveguide,ridge gap waveguide and groove gap waveguide.And combining the advantages of different transmission lines,low profile,low loss,high efficiency hybrid feeding array antennas are designed.On the basis of the existing research on substrate integrated gap waveguide,a new type of double layer transmission line is proposed and used in two examples,providing new ideas for future research.