Micro-Coaxial Fed 18 to 110 GHz Planar Log-Periodic Antennas With RF Transitions

Design, fabrication, measurement setup, and performance of a surface micromachined 18 to 110 GHz planar log-periodic antenna are discussed. The antenna design features a monolithically integrated five-step rectangular-coaxial line impedance transformer used to match the antenna´s nominal impedance of 160 Ω to the 50 Ω system impedance. Three measurement transitions are developed to characterize the impedance and far-field performance of the antenna over the full operational bandwidth. Measured data are compared to simulations to assess technology maturation and the performance of the fabricated devices. Realized gain above 3 dBi with stable co-polarized patterns and VSWR under 2:1 are measured for the majority of the operational bandwidth.