Research On Some Microwave Modules Used In 5.8GHz ETC System

ETC (Electronic Toll Collection), as one of the services of ITS (Intelligent Transportation System), is a kind of electronic automatic charge system that is used by highways, bridges and tunnels. People are trying hard to explore and spread it. It can automatically identify the vehicles and achieve electronic toll by the wireless communication and information exchange between the roadside unit fixed on the roadway and the on bus unit fixed on the vehicle.Because of its advantages, ETC has obtained more attentions and will represent its action to the ITS in the future. Based on these backgrounds, this paper is mainly focused on some RF modules used in ETC system.The paper introduces the ITS system and analyzes the standardization of the DSRC (Dedicated Short Range Communication) . Then it describes ETC's development and status at home and abroad. Base on the demand of DSRC, the paper research and design a low-cost RF module used in the 5.8GHz ETC.In the first part of the paper, according to the performance indexes of ETC, a kind of high performance LNA applying in ETC microwave modules be simulated and optimized by the circuit simulation software ADS2003. The test results satisfied system requirements.In the second part, the theory of PLL is presented in detail. Afterward a low phase noise, low-cost, single structure PLL is researched and successfully designed. The phase noise and frequency stable of PLL are measured and satisfied the system requirements.Last, a new microstrip bandpass filter is proposed on the basis of traditional square filter in this paper, which solves the problems of radiation loss and big volume in the traditional filter. The filter can suppress higher order harmonic more effectively. Such a filter working at 1GHz was designed and simulated. The measurement result matched the design goal very well. This part will be a good reference for the filter used in ETC designing.