Dual-polarized slot-coupled patch antennas on duroid with teflon lenses for 76.5-GHz automotive radar systems

A dual-polarized 76.5-GHz microstrip patch and teflon lens antenna system w as designed, constructed, and tested, A receiver (RX) array of three dual-p olarized microstrip patches was coupled through a 10-cm-diameter lens to pr oduce radiation patterns with 3 degrees beamwidths and beam crossovers of - 3 dB, The transmitter (TX) consisted of a single dual-polarized microstrip patch coupled through a 2.5-cm-diameter lens to produce a 10 degrees beamwi dth. Slot-coupled patches were used to isolate the microstrip feed circuit from the radiating elements, The antennas and feeds were fabricated on comm ercially available 5880 Duriod substrates, Cross-polarization levels were l ess than -20 dB and were typically less than -30 dB over the entire beam at the design frequency, First sidelobe levels were no greater than -15 dB an d were typically closer to -20 dB, Stepped and unstepped versions of the LO -cm-diameter receive lens were designed and fabricated. Antenna system side lobes levels were lower with the stepped lens while the cross-polarization levels were comparable.