Antenna arrangement

Abstract

A radio frequency antenna arrangement for selective operation at orthogonal polarizations of electromagnetic radiation. The antenna arrangement comprises at least one radiating element, such as one or more antenna patches, each having a vertical polarization feed point and a horizontal polarization feed point. The arrangement also includes a vertical feeder circuit for coupling a radio frequency modulated electromagnetic signal to the vertical polarization feed point of the or each radiating element, a horizontal feeder circuit for coupling a radio frequency modulated electromagnetic signal to the horizontal polarization feed point of the or each radiating element and a terminating resistive load. A switch mechanism is provided for selectively coupling the electromagnetic signal to one of the horizontal feeder circuit or the vertical feeder circuit and for selectively coupling the load to the other of the horizontal feeder circuit or the vertical feeder circuit. In the first position of the switch the electromagnetic signal is coupled to the horizontal feeder circuit and the resistive load is coupled to the vertical feeder circuit and the antenna arrangement operates predominantly in the horizontal polarization. In the second position of the switch the electromagnetic signal is coupled to the vertical feeder circuit and the resistive load is coupled to the horizontal feeder circuit and the antenna arrangement operates predominantly in the vertical polarization. In a first embodiments of the invention the switch mechanism is located at the interface between two antenna housing parts and the required polarization is selected by mechanical alignment of the housing parts relative to each other. In a second embodiment of the invention the switch mechanism is integrated onto the feeder circuits.