An Efficient Low-Profile Low-VHF Antenna for Small Unmanned Ground Vehicles

A compact, low-profile, efficient, low-VHF antenna designed for small UGV systems is presented. In order to achieve further gain enhancement from a recent development in an electrically small efficient monopole antenna, a new design approach is proposed. A single 180-degree phase shifter comprising a common capacitive top loading and multiple high-Q air-core coils connected to each corresponding short vertical element is designed to produce in-phase radiating fields from the multiple vertical elements at resonance, thereby considerably enhancing the antenna gain. Under practical considerations, performances of the antenna before and after integrating it on a small UGV are carefully characterized via simulations and measurements. The results show that a peak gain of the antenna integrated on the UGV with omnidirectional radiation pattern is 0.48 dBi which is comparable to that of a miniature dipole whose height is 7.5 times larger, facilitating low-power wireless compact UGV communications and networking at low VHF.