Design of the Downconverter Applied in the Reader of 5.8GHz System of Electronic Toll Collection

Aiming at the reader in system of electronic toll collection, a kind of microstrip-line downconverter operated in 5.8 GHz, designed with ADS, is described in this article. The mixer adopts single-balanced structure, inputs radio frequency (RF) at 5.8 GHz and local oscillation (LO) frequency at 5.39 GHz, and outputs intermediate frequency (IF) at 410 MHz. It can provide with a conversion loss of 9.8 dB, LO to RF isolation of 29 dB, VSWR of 1.1 at port RF, noise figure of 9.3 dB in single sideband, 1 dB compression point at -5.5 dBm and TOI of double tune at 4.3 dBm. And the use of microstrip-line at the input ports refines the VSRW.