A Novel Compact Four-Way Power Combiner with an Embedded Microstrip-to-Waveguide Transition for Ka-band Power Amplifiers

A novel compact four-way power combiner is presented with measurement results. The design successfully integrates a microstrip to waveguide transition. The power combiner exhibits very low insertion loss in Ka-band. At 30 GHz, the power combiner has 14 to 8 dB of isolation, 20 dB of return loss and 0.54 dB of insertion loss, with efficiency higher than 88%. The structure offers a low-cost and very compact solution with dimensions of
$3.5\times 5\times 0.5$
cm. A power divider/combiner structure is also designed and measured based on the previous combiner and a T-junction power divider. The structure is very compact and designed on a multilayer Printed Circuit Board (PCB).