Abstract: A rectangular waveguide rotary joint that allows limited mechanical rotation of two rectangular waveguides around a common longitudinal axis. The joint comprises a first rectangular waveguide having a first waveguide flange and a second rectangular waveguide having a second waveguide flange, wherein the second waveguide flange is disposed adjacent to the first waveguide flange with an air gap disposed therebetween. An RF choke is formed in the waveguide flanges for reducing RF leakage caused by the air gap, and a low friction spacer system for separating the first and second waveguides to maintain relative alignment of the waveguides during rotation and maintain a substantially constant separation between the waveguides. The waveguide rotary joint provides for a low voltage standing wave ratio (VSWR) and low insertion loss exhibited over a +/-30 degree rotation range.

Abstract: A dielectric material having a dielectric constant which varies inversely with frequency, and preferably with the second power of frequency, fills the space between a radiator and a reflecting groundplane. The back-directed wave is reflected back to the radiator in phase with the directly radiated wave over a wide frequency band, increasing the radiator efficiency.