LAUSR

Based on spatial power combining technique using a novel waveguide‐to‐microstrip transition, this article proposes a wideband compact double‐layer two‐level power amplifier composed by six commercial power amplifier chips for millimeter‐wave applications. Double antipodal fin line transition and second‐order Wilkinson power divider/combiner are developed for the spatial power combining circuit. Furthermore, the proposed power amplifier is fabricated with over‐mode waveguides. When the input power is 10 dBm, the measured output power reaches up to 23 dBm, and reveals a very small output power variation about 1.4 dB over a bandwidth of 43% from 36 to 56 GHz. Therefore, the proposed power amplifier can be widely used in millimeter‐wave transceiver modules as well as THz sources, due to its excellent wideband performance.