Development, manufacture and testing of a planar-array L-band antenna

A circularly polarised 1.5 GHz antenna was built and tested for use as an earth coverage antenna for use on board geostationary satellites. A rigid foam panel of extremely low dielectric loss coated with aluminium on the surfaces to give a sandwich effect forms the interior of a TE sub 50 resonator. The slot pattern is etched on one broadside of the skin. During development, sandwich and frame construction methods were evaluated, a structural analysis using NASTRAN performed, and tests for tests for dielectric losses of foams made. Foams were also tested for density variations, tensile strength, and outgassing. Thermal control considerations are given. The rear of the antenna is covered with superinsulation. Far field measurement tests show maximum gain 19.4 dB; gain at edge of earth 15.2 dB; ellipticity at edge of earth 2.5 dB and fundamental resonance 140 Hz. The reduction in gain due to the foam is less than 0.1 dB.