A High Efficiency Antenna with Horn and Lens for 77 GHz Automotive Long Range Radar

A high efficiency antenna with a pyramidal horn and a dielectric lens for a 77 GHz long range radar for automotives is presented in this paper. By introducing a single patch antenna installed into the input aperture of the horn, the transmission loss of the feed line on an antenna substrate was reduced so as to increase antenna gain. The proposed antennas for the transmitter achieved an antenna gain of 23.5 dBi and an antenna efficiency of 32.3%, which is 1.6 times as large as that of a conventional series fed microstrip patch array antenna with almost the same opening area as the proposed antenna. The proposed antenna provided an azimuth 3-dB beamwidth of 16 degrees, whereas the conventional series-fed microstrip patch array antenna had that of 10 degrees. An antenna for a receiver with the same topology of the antenna for the transmitter also gave an antenna gain of 20.5 dBi per one channel and an azimuth 3-dB beamwidth of 28 degrees. An antenna system for a long range radar composed of the proposed single transmitter antenna and the receiver antenna with two channels could provide a two-way antenna gain of 47.0 dBi and an azimuth 6-dB beamwidth of 23 degrees.