The in-orbit testing of a communication satellite involves the measurements of key communication parameters, which determine communication subsystem behavior and verify the design. Some of the tests, specifically those involving the satellite's antennas, are unique in that they require satellite antenna motion in both azimuth and elevation. They can only be conducted in the postlaunch period prior to the operational phase of the satellite. The focus is on the antenna tests, in order to verify antenna pattern design and put a bound on satellite antenna crosspolarization isolation, or lack of it, by comparing in-orbit test results with computer predictions and range measurements. Measurement procedures and instrumentation for the in orbit measurement of satellite antenna parameters are considered. The measurement procedures are reflected in equations in which the unknown parameter is expressed by measurable or calculatable quantities. The measurement error is evaluated on the basis of the parameter equation and component error estimates. >