Electrically small hemi-cylindrical-shaped multilayered very high frequency antenna for underground mine communication

This study presents the design of an efficient, moderately high gain and portable antenna operating at 58.27 MHz. The proposed antenna is a multilayered hemi-cylindrical shaped structure, which works on the principle of resonant inductive coupling using a multi-turn loop. An equivalent circuit, which takes into account the near field coupling effects, is also developed. The proposed antenna is electrically small with a finite ground plane with $ka \simeq 0.28$ka similar or equal to 0.28 and has an overall volume of 0.038 lambda(0) x 0.058 lambda(0) x 0.058 lambda(0). The antenna exhibits a gain of 3.43 dBi and an efficiency of 92.5% as obtained from measured results at the resonant frequency. The measured fractional bandwidth and the Q(ratio) of the antenna are 0.547 and 8.647%, respectively. The results obtained from electromagnetic simulation matches with that obtained from the equivalent circuit and the measured results. The antenna can operate at the lower very high frequency (VHF) frequency range for applications, which require electrically small portable antennas such as underground mine communication.