A printed monopole ESPAR antenna for Truck-to-Truck communications

Driver safety, traffic efficiency and green transportation can be significantly improved by Truck-to-Truck (T2T) communications. This paper proposes a 5.9 GHz Electronically Switched Parasitic Array Radiator (ESPAR) antenna that employs three printed monopoles as array elements. The antenna demonstrates a reconfigurable radiation pattern and compact dimensions that make it ideal for installing it in the side mirrors of a heavy duty vehicle (truck). By adjusting the voltage supply at two PIN diode switches, the antenna can operate in three different states and provide three different radiation patterns (one quasi-omni, two directive beams) to the T2T link user. An ESPAR antenna prototype is manufactured and experimentally characterized, demonstrating a good agreement between simulation and experimental results. The proposed antenna exhibits a satisfying impedance matching and a considerable gain enhancement in the two opposite directions when the antenna operates in the directive mode. An interesting investigation is also performed on the exact location of the antenna inside the truck side mirror.