N-way spatial power combining in SIW for high power generation MMICs-scalability bounds

An N-way transition between an array of amplifiers and a single substrate integrated waveguide (SIW) is presented. Its operation principle is based on excitation of the spatially distributed TE10 mode with an array of parallel and strongly coupled microstrip lines (MLs). The paper discusses and evaluates the approximate scalability bounds of such a structure in terms of the number of input channels. The model shows that, by employing a thin substrate, more amplifiers are capable of interfacing a single SIW to increase the output power, which is an important conclusion in regards to a future on-chip implementation of the structure. The model has also been validated by numerical simulations