Design of a Low Frequency and Wide Band Reflector Antenna Feed for Future Earth Observation Radiometers

A complete reflector antenna architecture solution has been developed for Cryorad mission operating from 400 MHz to 2 GHz. This paper analyzes the antenna feed requirements and proposes an array feed solution comprised of two different frequency feeds. The design and analysis of one the proposed conical logarithmic spiral feed have been carried out. More than 10 dB of directivity radiation pattern from 900 MHz up to 2 GHz with a directivity stability of ±0.5dB using only a 130 mm diameter feed has been developed. Single circular polarization is achieved with an axial ratio under 1 dB within the complete operating band. The proposed feed is ideal for use in satellite due to its reduced size and mass.