An Experimental Study of Cylindrical Antennas Radiating in or Near a Lossy Half Space.

Abstract : Conducting structures residing near, within and partially within a lossy half space are investigated experimentally. The conducting structures are modeled by monopole antennas, and the lossy half space is modeled by the water within a non-metallic tank. Antenna aperture admittances are obtained using swept-frequency network analysis techniques with automated data collection and reduction. Results are compared to results of numerical analysis conducted as a related project. A sleeve monopole is oriented normal to the water surface with driving point near the bottom of the tank and source gap (aperture) in air. Gap height above the water surface, antenna radius and monopole length are varied. Electromagnetic properties of the water are varied by addition of NaC1. Coax-fed wire antennas are mounted perpendicular to a ground plane which is normal to and intersects the water surface. The antennas used are a straight-wire antenna in which the monopole is parallel to the water surface and a bent-wire antenna in which the wire is partially immersed in water. Height of the aperture above the water is varied. A coax-fed cylindrical monopole antenna is mounted perpendicular to a ground plane which is in contact with the water surface so that monopole and aperture are immersed in water. (Author)