Precise Microwave Power Density Calibration Method Using the Power Equation Techniques.

摘要

A precise means has been developed for providing an absolute plane-wave power density calibration of microwave hazard probes. The method involves the use of an anechoic chamber and a waveguide pyramidal horn whose gain has been calibrated by the three-antenna method. The power equation techniques developed by Dr. Gleen Engen of the National Bureau of Standards were used to provide highly precise measurements of mismatches to the various antennas from their respective sources or loads. The power equation techniques also provide the basis for precise determination of absolute power delivered to the calibrated antenna from an arbitary high-power source. Since these techniques do not require the use of precision coaxial or waveguide components,they are well suited to high-power systems. Error analyses are presented for all aspects of the calibration system,including antenna gain,absolute power delivered to the antenna,and multipath errors. A total system uncertainty of 0.69dB (worst case) was computed for a 2450-MHz calibration system. Future refinements could reduce this uncertainty to 0.41dB.