Measured field patterns of bare and insulated linear antennas in a material medium

Apparatus designed to measure the electric field of bare and insulated linear antennas in fresh water is described. The transformation of the measured field to obtain far-zone patterns is discussed. Field patterns for bare antennas and for insulated antennas with concentric and eccentric insulation are compared, and the shaping of the pattern that can be obtained using the insulation is described. The measured field patterns are in good agreement with theoretical patterns calculated from recently developed theories.