Patch antenna array for X-band FMCW sensor: An antenna system for detection of obstacles in near vicinity of a helicopter

The paper describes concept of the patch antenna array for X-band FMCW (Frequency Modulated Continuous Wave) radar. This antenna is part of a system for detection of obstacles in the near vicinity of a helicopter. The intended function of this system is to detect and inform the flight crew of obstacles while maneuvering at low airspeed typically close to the ground. The antenna works at center frequency 9.5 GHz with bandwidth of 450 MHz. The antenna is fabricated by microstrip technology. Since the broadband antenna is need, the antenna consists of two dielectric layers. The first layer consists of radiation elements (patches). The second layer has, on its top side, a ground plane and on the bottom side, a signal distribution network for a series-fed patch antenna array. Between these two layers is a gap which allows a required bandwidth to be achieved.