Performance of Aftermarket (DSRC) Antennas Inside a Passenger Vehicle 2011-01-1031

A vehicle's safety system capability can be enhanced by a cooperative Vehicle-to-Vehicle (V2V) system in which vehicles communicate their driving status data, such as location and speed, using a common Dedicated Short Range Communication (DSRC) protocol. The effectiveness of the V2V applications will depend on the number of the vehicles equipped. Market penetration significantly influences the effectiveness of V2V safety applications. Previous research indicated that it could take decades to reach 95% DSRC safety device penetration in the market if only the new vehicles are equipped with the DSRC transponders during manufacturing. In order to raise the market penetration of such technology in the foreseeable future and provide a safety benefit to the early adopters, a scenario that involves retrofit and aftermarket DSRC devices is suggested by U.S. Department of Transportation (USDOT). A typical retrofit for a passenger vehicle may mean that a DSRC antenna will be installed on the roof of the vehicle and the cable will be routed to the transponder somewhere inside the vehicle. An aftermarket device installation typically means that the antenna is placed inside a vehicle on the dashboard. However, the RF signal may be impeded by glass windows, metal pillars, seats, and even the passengers. Also, there is no built-in ground plane as in the case of a roof top mount. This paper examines the performance of commercially-available DSRC antennas mounted inside of a vehicle, shows results of field trials using 0 dBi and 9 dBi horizontal gain antennas, identifies issues, and suggests possible placements of the antenna in a vehicle.