Optimal Tilt Angle of Reader Antennas for Truck Tolling Based on UHF RFID

Free flow truck tolling systems based on Ultra High Frequency (UHF) Radio Frequency Identification (RFID) need a highly reliable communication between the readers and transponders. To this end, a large number of reads of the transponders is desirable, which can be affected by physical effects (e.g. multipath propagation, Doppler effect) as well as the chosen protocol parameters (e.g. Miller coding). There has already been a great interest in investigating these effects. However, to the best of our knowledge, the effect of the tilt angle of the antenna on the number of reads has not been covered yet. This paper describes an implemented simulation framework in MATLAB which allows to find the optimum tilt angle for a single patch antenna and a patch-based antenna array for truck tolling at one lane. It turns out, that in both cases the optimal angle is about 71°.