Ultra-wideband SPDT and SP8T Switches using Silicon-Glass PIN Diodes for Microwave Medical Imaging

In microwave medical imaging system, a monostatic radar approach can be used together with Gaussian pulse (with an ultra-wideband (UWB) frequency). In this system, eight antennas can be used for transmitting and receiving the Gaussian pulse signal and controlled by radio frequency (RF) switches. Therefore, this paper presents the performance analysis of three different single pole double throw (SPDT) switch topologies (Design A, B and C) using discrete silicon-glass PIN diodes. Then, the best performance of SPDT switch was built up to be a single pole eight throw (SP8T) switch configuration to connect with eight antennas. As result, Design C showed the highest isolation performance compared to others. Then, based on the SP8T switch of Design C, it resulted that the insertion loss was less than -2 dB and the return loss was more than 10 dB from 1 to 15 GHz. Meanwhile, the isolation bandwidth (at the minimum isolation of -15 dB) was from 1 to 14 GHz (with 13 GHz bandwidth).