A novel design of single balanced mixer for Ka-Band satellite transponder simulator

The design, assembly, and measured results of a low cost, compact, low conversion loss, single balanced Schottky diodes mixer for Ka-band satellite transponder simulator have been proposed. A microstrip rat-race ring at the local oscillator (LO) frequency is constructed as a 180 degree hybrid coupler, which also satisfies the amplitude and phase characteristics requirements at the radio frequency (RF). An input network with a short stub and an output network including an open stub and a lowpass filter with bonding wires across the rat-race ring are optimized to realize the compact, low conversion loss mixer. The measured results show that the conversion loss is less than 7.2dB from 20.2 to 20.9 GHz, which is the intermediate frequency (IF), and the frequency response ripple is less than 1.5 dB in 700 MHz bandwidth, and less than 3dB in 1.6 GHz bandwidth.