94-GHz Log-Periodic Antenna on GaAs Substrate Using Air-Bridge Structure

We fabricated a compact, 94-GHz log-periodic planar antenna on GaAs substrate. We used millimeter-wave monolithic integrated circuit (MMIC) process technology to fabricate the on-chip antenna. An air-bridge crossover is used to replace the conventional bonded structure for crisscross connection, which is compatible with active devices and circuits. The fabricated antenna chip size is 1.2 x 2.6 mm(2) Measurement results show that this antenna can operate from 87 to 99.5 GHz with its return loss better than -10 dB. At 94 GHz, the log-periodic antenna has a return loss of -11 dB and 4.8 dBi of gain.