Leveled Sub-Microwave Sweep Measurements with Unleveled Sources and only One Diode

In the sub-microwave region it is quite impossible to obtain matched pairs of detectors and therefore to perform leveled sweep measurements. Besides large power variations available sweepers show frequency unstabilities, thus digital storage and substraction methods fail. Here the RF power is split in a signal and a reference path. Both of them are chopped synchroneously but alternately by a quasi optical waveguide chopper. After the signal has passed the test object both paths are recombined. The sum signal is detected by one diode and passes through a logic circuit to the signal and the reference inputs of a ratio meter at appropriate times. Power variations of 5.5 dB have been reduced to 0.4 dB, test unit insertion loss may vary more than 20 dB.