A Planar Four-Way Power Combiner Network with High Isolation Based on Mixed Architecture

In this paper, an X-band mixed microstrip and substrate integrated waveguide (SIW) four-way power combiner network with fully isolated performance is proposed. The power combiner network provides a high power capacity while maintaining the miniaturization of the structure. The input network can be considered as a four-way power divider composed of three microstrip 3-dB couplers, while the output network consists of three SIW 3-dB couplers. The directional couplers can enhance the isolation among the high-power signals of the four transmitting paths. In addition, the active power combiner utilizing X-band Gallium Nitride (GaN) power amplifier MMIC chips has also been designed. To demonstrate the feasibility of the above concept, the proposed prototype is developed. The experimental results show that the proposed power combiner attains a bandwidth ranging from 8.8 to 10.5 GHz, with a minimal insertion loss of 2.3 dB.