A Tapered-Slot Antenna with Emulated Continuous Resistive Loading

Ultra-wideband antennas for subsurface imaging are usually heavily loaded to widen the frequency band of operation and reduce clutter caused by the antenna ringing. The paper presents two designs of tapered-slot antennas in which the ringing has been partially suppressed by corrugations and/or resistive films applied on the antenna flares. It was found that resistive loading of the flares diminishes return loss of the antenna and increases its directivity at low frequencies at the cost of some drop in efficiency. In addition, the loading reduces coupling in the transmitting-receiving antenna pair that improves performance of subsurface radar.