Miniaturized dipole antenna development for low frequency ground penetrating radar (GPR) system

A miniaturized symmetrical dipole antenna with extra radiating arms is proposed for low frequency operation (100 MHz) in ground penetrating radar applications to achieve high depth penetration at low resolution. The dipole antenna design is of total dimension 66.5 cm × 22 cm. A parametric study of antenna performance is performed via simulation with Agilent Advanced Digital System software which indicates an optimum length of 15 cm for the extra arm with a gap of 5 cm between the dipole arm and extra arm. The results are validated experimentally in room conditions with a prototype antenna fabricated on 1.6 mm thick FRA substrate, copper layer thickness of 17 µm. The antenna operating at a centre frequency of 104 MHz and bandwidth of 8 MHz for VSWR ≤ 2 achieves a 55% reduction in length compared to a conventional dipole operating at 100 MHz while delivering typical dipole radiation pattern with directivity gain of 2.06 dBi.