An X-band Spatial Power Combining Using Rectangular Waveguide with Dielectric Lens

Because the performance of the output power and the bandwidth of the monolithic microwave integrated circuit (MMIC) amplifier is being improved in recent years, the development of a power combining technique with high efficiency becomes the next research target to enhance the output power. In this paper, an X-band 3-way power combiner for MMIC chips using rectangular waveguides is fabricated and tested for its S-parameters with microstrip thru-lines. To improve the combining efficiency, phase imbalance on MMIC inputs is minimized with a new type low-loss dielectric lens. This dielectric lens is very suitable for power combining system because this lens can be fabricated easily and withstand high power output compared to the conventional dielectric lens. The measured combining efficiency is higher than 75% in 8.5-11.5 GHz.