Efficient millimeter-wave high power generation with spatial power-combined feeding element

An efficient transition from a grid of amplifiers to a single substrate integrated waveguide (SIW) is presented. It is based on the excitation of the spatially distributed SIW mode with an array of parallel and strongly coupled microstrip lines (MLs), each of which is connected to an amplifier. The proposed configuration is optimized by minimizing the `active' reflection coefficients at the TL ports. This equalizes the amplifier optimal load impedances and excites the TE10 SIW mode most efficiently. Also, signals are transferred with nearly uniform power distribution at the amplifier outputs. Numerical results show that this configuration can generate 16× more power per unit volume relative to a single microstrip-to-SIW transition, while offering a larger bandwidth. A prototype has been developed to validate the proof-of-concept.