Accession Number : AD0693220

Title :   RADIATION FROM AN ANTENNA ENTERING THE MARTIAN ATMOSPHERE.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA INST OF TECH PASADENA ANTENNA LAB

Personal Author(s) : Norgard,John D.

Report Date : JUN 1969

Pagination or Media Count : 168

Abstract : The interaction between the ionized wake of a capsule entering the Martian atmosphere and the circularly polarized radiation emitted by an antenna located on the aft part of the capsule is theoretically investigated. A simplified mathematical model of the atmosphere of Mars, the entry-trajectory of the capsule, and the flow field surrounding the capsule are used in the analysis. The near wake of the capsule is approximated by a cylindrically stratified plasma shell consisting of n plasma regions. The plasma in each region is assumed to be homogeneous, anisotropic, and conducting, and moving at a uniform velocity relative to the antenna. The antenna is represented by a turnstile antenna located off-axis above an infinite ground plane and operates at the signal frequencies of 400 MHz and 2.295 GHz. The analysis shows that blackout occurs during entry. Before and after blackout the radiation exhibits an on-axis null region whose angular extent is proportional to the electron concentration of the plasma. (Author)

Descriptors :   (*ANTENNAS, MARS PROBES), (*MARS PROBES, *RADIO TRANSMISSION), (*TELEMETERING ANTENNAS, MARS PROBES), ATMOSPHERE ENTRY, BLACKOUT(PROPAGATION), PLASMA SHEATHS, ATMOSPHERE ENTRY, PLANETARY ATMOSPHERES, ANTENNA RADIATION PATTERNS, ELECTRON DENSITY, WAKE, THESES

Subject Categories : Unmanned Spacecraft
      Telemetry

Distribution Statement : APPROVED FOR PUBLIC RELEASE