Design of a Flexible Minkowski-Like Pre-Fractal (MLPF) antenna with different ground planes for VHF LMR

Abstract

This work investigates the suitability of a flexible Minkowski-like pre-fractal antenna (MLPF) for application in the Very High Frequency (VHF) Land and Mobile Radio (LMR) frequency bands (136-174 MHz). The proposed center-fed, third iteration antenna has been manufactured using both copper tape and ShieldIt Super, a conductive textile. It has been tested on four types of ground plane, i.e. rectangular, fractal Minkowski, meander line and L-shaped. It is observed that an L-shaped ground plane performs the best, and provides an additional frequency tuning parameter to the overall structure. Simulated and measured S11 show a good agreement and the proposed antenna is working within the desired frequency range. A simulated gain and efficiency of more than 1.9 dB and 76 %, respectively, are obtained. The measurement in a Satimo SG64 anechoic chamber provided 0 dB gain and about 48 % efficiency.