Electrically small magnetic GPR antennas

This paper examines the application of small magnetic loop antennas for ground penetrating radar (GPR). Making antennas smaller is of considerable practical interest, especially for deeper penetration GPR application that require lower frequency content (i.e., <50 MHz) GPR antennas are also required to be sufficiently broadband to facilitate an appropriate range resolution. A modelled comparison of the bandwidth constraints shows that an electrically small magnetic antenna can be constructed with the rise of material properties (i.e., ferrites) to approach the Chu theoretical minimum Q more closely than an equivalently sized electric dipole antenna. Numerically modelled and experimentally measured results, in terms of the Q for a small magnetic loop antenna over a lossy dielectric ground half-space are also examined. Close proximity to the half-space is shown to significantly improve the impedance bandwidth.