Space Shuttle Electromagnetic Environment Measurement

The results of a study leading to a method for carrying out an electromagnetic environment experiment (EEE) using the NASA Space Shuttle are herein described. The objective is to map intentional and nonintentional electromagnetic emissions from the earth's surface in the microwave range. The experiment proposed below emphasizes emissions aimed tangent to the earth's sur­ face and normal to the earth's surface, but the method can be adapted for use at an angle above the horizontal. High-gain antennas look toward the horizon or below and rotate, sweeping out a cycloidal swath oh the earth's surface as the satellite moves in its orbit. We develop electrical and mechanical sweep parameters and examine both the probability that the receiver's main beam will correctly detect a given emitter, and the probability that the receiver will erroneously measure powerful emitters though not pointing to them. A brief survey of the emitter densities that the receiver is likely to see provides a rationale for the selection of certain design parameters.