Accuracy of a Temperature-Compensated Precision RF Power Bridge

A temperature-compensated de-substitution-type RF power bridge is described. Temperature compensation is accomplished through utilization of dual bridges and the widely used dualelement temperature-compensated thermistor mount. A review of the RF-to-dc substitution technique is made prior to the description of the bridge. An analysis of the measurement accuracy shows total errors of less than 0.14 percent at 1 mW and less than 0.085 percent at a 10-mW RF power measurement. These errors include those arising out of ambient temperature variation.