Investigations into the design of a spatial power combiner employing a planar transmitarray of stacked patch antennas

Investigations are performed into the design of a transmission type X-band spatial power combiner involving the tile configuration of microstrip patches coupled to input and output ports of individual amplifiers. In order to obtain an increased operational bandwidth of such a power combiner, stacked microstrip patch antennas are chosen in the present design. Various configurations of such antennas are manufactured and tested. Using these antennas, passive transmission-type unit cells are built and assessed in terms of return and insertion losses. The experimental results show that all of the developed unit cells exhibit high return loss over an increased bandwidth. However, only one shows small insertion losses. This configuration is used to build active unit cells of the power combiner.