A pair of dipole antennas for controlling polarizations

Abstract

AbstractIn maritime satellite communications, the fading of the satellite direct wave due to interference from sea return waves is a serious problem which causes difficulties in the communications. As a result, methods of reducing the effect of sea return waves have recently been investigated. This paper proposes an antenna configuration that permits such fading effects to be reduced by controlling the polarization for waves in the direction of the sea return wave (we call it “the reserved direction”). At the same time, the polarization loss for the satellite direct wave is made small. the present configuration is composed of a pair of dipole antennas with a reflector. Controls of these wave sources (current distributions) enable us to synthesize the polarization in the reserved direction which is in opposite sense of rotation with that of the sea return wave, has the same axis ratio, and whose major axis is orthogonal to that of the sea return wave in the reserved direction. This reduces the fading effects greatly. Furthermore, even when the antenna shows a movement according to the vessel movement, we have adopted a system which corrects electrically the antenna fluctuation resulting in saving the mechanical altitude stabilizing equipment. We describe first the fundamental characteristics of the present antenna configuration. Wave source characteristics for controlling the polarization in the reserved direction for simple examples have been presented, along with the theoretically computed results of the axis ratio and radiation pattern, etc. Finally, the results of model experiments have been presented to support the theoretical considerations.