Optimization of low-profile antennas for applications in unattended ground sensor networks

An investigation into the design of optimal low-profile, small antennas for unattended ground sensor (UGS) networks operating at VHF or higher frequencies is featured in this study. Because UGS transceivers are intended for operation near the ground, ground proximity effects become extremely important for considerations related to antenna efficiency, input matching, radiation pattern, and the overall path loss between the transmitter and receiver nodes. While vertical wire antennas are shown to be less susceptible to path loss, a low-profile alternative is required in fabricating cheap, monolithic on-chip, miniaturized systems. In seeking an optimal design, the performances of different transceiver systems utilizing different types of antenna structures including the dipole, loop, ordinary circular slot, and cavity-backed circular slot are analyzed using a full-wave hybrid approach consisting of the moment method in conjunction with an asymptotic field propagation model. The figure of merit for comparison among the various configurations is identified as the efficiency factor calculated from the ratio of the radiated power at the transmitting terminal to the received power at the receiving terminal. To the best of our knowledge, the study as presented here on the performances of low-profile, small antennas including ground proximity effects is the first of its kind