A Compact Ferrite-Based Dipole Directional Antenna for Borehole Radar Application

A compact ferrite-based directional antenna has been designed to serve in a directional borehole radar system with a center frequency at 100 MHz and a bandwidth from 70 to 180 MHz. The parameters of the antenna are with a 6:1 power front-to-back ratio and a ±60° directional diagram at half peak amplitude, and the tailing duration of the receiving pulse was about a half pulsewidth while the antenna was placed in the granite borehole and fed by a monocycle pulse with 10-ns duration. The dimensions of the antenna are 48 mm × 54 mm × 440 mm . Experimental results are in good agreement with the simulation results offered by the commercial software (CST MWS) and suggest that the proposed antenna is suitable for the directional borehole radar application.