Millimeter wave antenna with frequency selective surface (FSS) for 79 GHz automotive radar applications

Abstract

In this paper a high gain aperture-coupled membrane antenna with a frequency selective surface (FSS) on a superstrate layer has been investigated. The base membrane antenna consists of a microstrip patch on the top of Roger RT-5580 substrate, supported by FR4 and is excited through an aperture fed by substrate-integrated waveguide (SIW). The CST Microwave Studio simulation results show that the proposed membrane structure has an impedance bandwidth (BW) of 8.85% from 75.97 to 82.96 GHz with a gain of 6.29 dBi at 79 GHz. To improve the gain, a superstrate layer is loaded above the membrane antenna, which increases the gain by 9.11 dB at 79 GHz. Furthermore by using FSS under superstrate layer, the gain is again increased by 2.5 dB. The total antenna structure provides a gain of 17.9 dBi at 79 GHz by keeping the same BW. The measured results are provided for the input matching (S11) only, the simulated results for the antenna gain and radiation patterns are obtained with the use of CST and are validated by using HFSS. The measured S11BW of the total antenna is from 75.57 to 84.18 GHz (10.89%), which is in agreement with the simulated results.