Research On W-band Planar Array Antennas

Compared with the low-frequency band,the millimeter-wave band(30 ? 300GHz)has become the focus of research in recent years due to its wide frequency band,small antenna size,and high resolution.The W-band(75 ? 110GHz),especially 77 GHz and 94 GHz,has a small atmospheric attenuation in the vicinity,which is undoubtedly a popular research frequency in various fields such as vehicle radar,missile fuze and wireless communication.Summarizing the above discussion,this paper has conducted in-depth research on W-band planar array antennas based on microstrip lines and substrate integrated waveguide structures.The main parts of the paper include the following aspects:First,a 45° linearly polarized comb-shaped microstrip array antenna was designed.The comb-feeding method was used to replace the traditional series-feeding method to reduce the transmission loss of the antenna.In addition,considering that this antenna is used in an automotive radar system,the array element is selected to be offset by 45° to obtain a 45°linearly polarized wave in this paper,for reducing electromagnetic interference to the oncoming vehicle.At the same time,a reflection-canceling slit is set for each array element to cancel the reflection energy of the array elements,which further solves the phase mismatch problem between array elements.A T-shaped feeding network is designed for the array antenna and compared with the traditional multi-stage cascaded Y-shaped feeding network,which shows the superiority of the structure performance.The final design of the comb-shaped microstrip antenna array antenna is processed and simulated.The results show that the transmitting antenna gain is 24.2d Bi and the maximum sidelobe level is-17.9d B.The receiving antenna gain is 16.1d Bi and the maximum sidelobe level is-18.4d B.Then,to solve the problem of high frequency transmission loss of microstrip antenna,a substrate integrated waveguide slot array antenna is designed.The equivalent analysis method is used to analyze the radiation characteristics of the equivalent waveguide isolated slot model.The initial size of each slot in the array unit is set according to the Taylor distribution requirements.After that,the antenna feed network was designed using a substrate integrated waveguide structure,and the substrate integrated waveguide slot array antenna is processed and simulated.The results show that the transmitting antenna gain is 13.7d Bi and the maximum sidelobe level is-18.7d B.The antenna gain is 12.8d Bi and the maximum sidelobe level is-13.3d B.Finally,a circularly polarized array antenna is designed.This antenna obtained the size design value of the antenna unit,using the theory of magneto-electric dipoles,and analyzing and evaluating the influence of various structural parameters on the antenna performance.And using the substrate integrated waveguide as the antenna's feeding network,the waveguide and the microstrip-waveguide transition structure as the transmission layer of the antenna,a multilayer back-fed array antenna structure was finally realized.Simulation analysis of the antenna shows that the antenna has a very symmetrical radiation pattern,with a gain of 14.1d Bi,an E-side side lobe level of-10.8d B,and an H-side side lobe level of-11.9d B,a-10 d B's impedance bandwidth of 17.4%.According to the research results,a national invention patent application(application number: CN201910298837.1.)was completed.