Wideband low loss signal couplers use an electric field antenna for voltage detection and a magnetic loop for current detection both placed inside and coupled to the center conductor of a coaxial or parallel plate airline. The signal coupling factor increases with frequency thus favoring detection of harmonic components generated by the nonlinearly operated RF transistors. In order to adapt also to various power levels and associated harmonic receiver sensitivity the detectors can be adjusted such as to vary the basic level of coupling. A calibration method allows considering non-infinite directivity of the signal couplers to be accurately considered even when they are terminated with very high VSWR, generated by impedance tuners connected to the signal couplers.
Adjustable Signal Sampling Sensor and Method / 8,841,921
Tuesday, September 23, 2014