A fully planar power combiner using microstrip patch arrays

Due to congestion in the low microwave frequency bands new commercial and military applications are focused on the use of upper microwave and millimeter-wave bands. Some of these applications include automotive collision avoidance, automatic toll collecting, radar and wireless communications. In many of these applications the currently available individual solid-state devices can not meet power requirements. In order to overcome this problem, suitable power-combining schemes can be used. Circuit-type power combiners have to be excluded due to significant power losses at the upper microwave and millimeter-wave frequencies. In this situation, other types of power combiners such as spatial or quasi-optical power combiners, which avoid or minimise circuit losses, can be applied. The research work reported is concerned with a fully planar power combiner that uses microstrip patch arrays to combine power from solid-state amplifiers. Two varieties of this combine one having coaxial input/output ports and the other using a coaxial input port and a free space as a power-combining medium, are investigated.