The evolution of power combining techniques: From the 60s to today

The evolution of power combining techniques is traced from the emergence of the first power microwave solid-state device, the IMPATT, to the present. The IMPATT spawned the Kurokawa and the resonant cavity combiners, while the 3-terminal device (starting with the GaAs MESFET) gave birth to planar structures using evolving MIC techniques. Two-way combiners in the form of Wilkinson, branch-line, and Lange were used to fabricate planar N-way corporate combiners in microstrip media. Non-planar radial, conical and spatial combiners emerged later to produce high-order combining and high output power. In the years since the explosive combiner growth in the 70s and early 80s, the 2-terminal device has been largely replaced by 3-terminal devices, and GaN has become the dominate power device technology at frequencies ranging from L to W-band.