A Horizon Sensing Vertically Oriented Radiometer Antenna Study

A satellite system antenna design suitable for observing the 5 mm emission from the oxygen of the earth's atmosphere in order to obtain a vertical sense is presented. An approach capable of reducing the uncertainty in the vertical error to less than 1 arc minute (3 sigma) is discussed. A trade-off analysis between performance and system complexity is included. It is shown that a significant simplification in complexity can be realized if the accuracy goal is increased to 2-3 arc minutes (1 sigma) of error.

The antenna performance requirements are discussed with reference to the performance requirements imposed on the other major subsystems of the earth vertical sensor, particularly the radiometric receiver and the measurement coordinate system.

This study and investigation was initiated under Contract No. NAS 12-2001 for the purpose of determining the feasibility and design of a precise and reliable earth vertical tracking antenna.