Analysis and design of tapered finline arrays for spatial power combining

In an effort to enhance the performance of a previously proposed waveguide-based spatial power combiner, an optimal tapered finline array was designed to improve the gain flatness and return loss of the power combiner. An optimal taper was designed based on the theory of small reflection and the design equations for Klopfenstein (1956) tapers. Due to its simplicity in developing computer codes, the spectral domain method was used to compute the propagation constants corresponding to a finline structure with various slot widths. The results of return loss measurements have shown good agreement with the simulation results, presenting a broadband frequency response and good return loss characteristics.