Last modified: 2014-02-19
Abstract
A dual-band dual-polarized feed for a symmetrical single-reflector antenna is presented in this paper. Antenna system receives telemetry information in the meter (120–225 MHz) and decimeter (625–650 MHz) frequency bands. Reflector has a low F/D ratio 0.25. The feed consists of two log-periodic dipole array antennas (LPDAs) formed by metallic tubes. Calculated aperture efficiency values (without taking into account matching and cable losses and shadowing of the feed screen and support structures) are about 51% in decimeter band and within 34…44% in meter band. Feeding coaxial cable wave impedances are equal to 75 Ohm and 50 Ohm for meter and decimeter band feed, respectively. A 75-to-50 Ohm coaxial section with a pair of parallel open-circuited stubs is used to match meter band LPDA with 50 Ohm low-noise amplifier input impedance. Measured VSWRs are less than 2.2 in meter band and about 1.8 in decimeter band.