Calibration requirements for EHF satellite communication systems

Abstract

The calibration and measurement support requirements of millimeter wave satellite systems such as MILSTAR have been investigated. The needs for measurements on satellite systems are reviewed. An overview of the various means available for calibrating antenna gain, one of the key measurements that needs to be accurately accomplished, is presented. Essentially three new measurement problems arise because of operating in the upper SHF and EHF frequency ranges. First, without adequate methods to measure the atmospheric loss, the accuracy of effective isotropic radiated power (EIRP) measurements in the 20-45 GHz range can be no better than 0.5-3 dB (depending on frequency and antenna elevation angle), which is inadequate for MILSTAR requi rements. Second, standards and measurement support services are not presently available from the National Bureau of Standards and are needed to support millimeter wave antenna gain and thermal noise measurements. Third, if the Sun and/or Moon are to be used for measuring Earth terminal G/T, Earth terminal antenna gain, or satellite EIRP in the millimeter region, they need to be appropriately characteri zed at those frequencies.

Investigation of Laser-Induced Plasma Processes.

“…At 100 nsec the 0 + temperature is about 3x10 4 K and from then on varies slowly. The temperature for 0 neutral at late time is determined to be -8000 K [15]. Thus, we assumed a temperature profile which has an exponential function from 0 to 100 nsec and behaves linearly from 100 nsec to I Asec.…”