Accession Number : ADP007445

Title :   Topex Spacecraft Dual-Frequency Radar Altimeter Antenna,

Corporate Author : JOHNS HOPKINS UNIV LAUREL MD APPLIED PHYSICS LAB

Personal Author(s) : Jablon, Allan R.

Report Date : FEB 1992

Pagination or Media Count : 15

Abstract : The design of the TOPEX Radar Altimeter antenna is described. The TOPEX/POSEIDON satellite is a joint U.S.-France (NASA-CNES) spacecraft scheduled for launch in 1992. The spacecraft will carry the TOPEX and POSEIDON radar altimeters, which will map the circulation of the global oceans. The TOPEX radar altimeter (NASA) is a dual-frequency altimeter operating at Ku- and C-bands. The POSEIDON radar altimeter (CNES) operates at Ku-band. A common antenna is used for the two altimeters. The antenna is a focal-fed 1.5 meter diameter parabolic reflector antenna. The feed includes a waveguide circuit to combine the three signals from the two altimeters. The radiating portion of the feed is a conical dual-depth corrugated scalar horn. The C-band signal is launched by a coaxial probe into the C-band circular waveguide feeding the horn. The two Ku-band signals are launched with orthogonal polarizations by an orthomode transducer. To achieve coupling (at Ku-band) to the horn through the large waveguide, a step discontinuity is used to generate TE11 and TM11 modes in the large waveguide.

Descriptors :   *ALTIMETERS, *ANTENNAS, *ARTIFICIAL SATELLITES, *RADAR, C BAND, CIRCUITS, CIRCULAR, DEPTH, DIAMETERS, DISCONTINUITIES, FEEDING, FREQUENCY, GLOBAL, KU BAND, MAPS, OCEANS, PROBES, REFLECTORS, SIGNALS, SPACECRAFT, TRANSDUCERS, WAVEGUIDES.

Subject Categories : Flight Control and Instrumentation
      Electrical and Electronic Equipment
      Active & Passive Radar Detection & Equipment
      Unmanned Spacecraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE