Stacked rectangular microstrip antenna with a shorting post for road vehicle communication

Intelligent transport system (ITS) has been used recently to enhance traffic safety and smooth traffic flow. Road vehicle communications system (VICS) is one of the ITS applications that gives traffic information to drivers. It is desirable that car antennas for VICS have uniform level of received signals from below a beacon antenna at the shoulder of road to far away along the road. Rectangular microstrip antenna (MSA) of TM/sub 01/ mode used as car antenna presently seems not to have radiation characteristics required for VICS. In this paper, a stacked rectangular MSA with a shorting post for VICS is proposed. The proposed antenna has the radiation characteristics required for VICS and is much smaller compared with the rectangular MSA used presently.