Multi-Band (L/S/C) Nested Concentric Cavity Coaxial Mode RF Feed for Autotrack Telemetry Systems

Abstract

Recognizing the current and future requirements of extending Telemetry, TT&C, Earth Resources operations into the C-Band (4400-5200 MHZ) arena, Orbit Communication Systems and Orbit Communication Ltd. are currently designing and testing a Tri-Band auto-tracking / receive / transmit feed technology combining dual polarization with multiple frequency band coverage (L/S/C) into a single feed that can be fitted onto new or existing antenna systems. This technology reduces footprint and minimizes life cycle cost, both of which are important considerations for both our commercial and military customers. This technology has been applied to a number of systems, including flyaway, fixed (or teleport) and shipboard, and is readily applicable to ground and mobile applications. The multiband feed design consists of coaxial, concentric waveguide cavities operating in TE11 and TE21 modes (Patent Pending). The large outermost cavities of the feed operate in the L/S frequency band while the innermost cavities operate at C-Band. The antenna is fed with orthogonally polarized inputs/outputs enabling polarization diversity in all bands. The coaxial cavity feed is ideal for this application because the feed produces high-efficiency, near-optimum illumination patterns and coincident phase centers in all three bands simultaneously. Because it is a waveguide design, the input power levels used in Telemetry and Satellite systems do not present breakdown problems. This type of feed has proved to be an ideal multiband illuminator for parabolic reflectors, and therefore could be used in many military and commercial applications that require multiband operation.