Electrically Small Platform-Based Antennas for an Unmanned Ground Vehicle

We present a design strategy for platform-based antennas operating on electrically small platforms such as unmanned ground vehicles (UGVs). Specifically, we report the design of a platform-based antenna operating at the lower end of the very-high-frequency (VHF) band for a small UGV with physical dimensions of 99 cm × 67 cm × 39 cm. The antenna is mounted on the bottom of the platform resulting in an extremely low-profile design and generating vertically polarized, monopole-like radiation patterns. Using characteristic-mode theory (CMT), performance metrics of the antenna including its maximum potential bandwidth and radiation patterns are investigated. The performance of the antenna when operating in a realistic operational environment is analyzed using full-wave electromagnetic simulations. A full-scale prototype of the antenna mounted on the bottom of the vehicle was fabricated and experimentally characterized. Finally, the design of this low-profile antenna is extended to a two-element antenna array mounted on the same platform and a prototype of this two-element array was fabricated. Basic experiments were conducted to study impedance matching and mutual coupling effects in this electrically small antenna array. The performance of this array as part of a two-element direction-finding system was investigated through computer simulations.