Dual-Band (S & C) Nested Concentric Cavity Conical Scanning RF Feed for Auto-Track Telemetry Systems

Abstract

Recognizing the need for dual band tracking in missions where mobility and weight are crucial factors, Orbit Communications Ltd. has successfully designed and tested an S & C dual band, dual polarized feed with a total system bandwidth greater than 80%. The feed uses high RPM conical scan auto-track technology combined with two co-located concentric apertures that is able to achieve excellent tracking accuracy in a small volume that can efficiently feed small dishes, starting from 1.2 meter. This solution meets the needs of field deployment and tactical forces looking for compact and easy-to-assemble field telemetry. The outermost cavity operates at S-Band and the inner cavity at C-Band. The antenna is fed with orthogonally polarized inputs, enabling polarization diversity in all bands. The coaxial cavities provide nearly uniform feed beamwidths as well as coincident phase centers in both bands, which make it an optimal feed for a parabolic dish. The conical scan rotates at up to 3000 RPM, giving excellent tracking fidelity. The entire feed system has a low blocking diameter of just 18 cm (7") that make it possible to feed the entire range of parabolic dish diameters.