A fast vector network analyzer on the basis of precise analogue frequency ramps

A system concept for a fast network analyzer (NWA) is presented. in contras t to a conventional frequency step-by-step signal source, the high frequenc y signal waveform of the fast NWA consists of a precise and highly linear a nalogue frequency ramp. The requirements concerning frequency stability and phase noise of the frequency ramps are similar to the synthesized frequenc y sources of the conventional NWA's. The use of fractional divider phase lo cked loop circuits allows to fulfill the stringent stability requirements o f the ramps. Also the signal processing differs from that of the conventional NWA. After filtering the raw data of the complete frequency sweep by a double Fourier transformation. the analytical signal is determined. Then conventional cal ibration procedures are applied in order to correct for the systematic erro rs of the last NWA.