High isolation diplexer design for autonomous vehicle

A diplexer for use in the communication system of an autonomous vehicle is designed for operation in the UHF (240-320 MHz) and GPS (1.2-1.6GHz) dual frequency bands and with isolation of better than 80dB. A lumped element model for the diplexer is first created and simulated. Based on the lumped element model, microstrip realization is then designed and simulated. All the diplexer designs are simulated in the Agilent Advanced Design System (ADS) software and the obtained results show an insertion loss of less than 1dB and an isolation of better than 90dB.