Application of Networks with Discrete-Fourier-Transform Properties in Intermodulation Measurement of Weakly Nonlinear Systems

Networks with Discrete Fourier Transforming scattering matrix -called DFT networks in the paper- have applications in multiple-beam telecommunication systems, where good intermodulation properties are needed. Properties of these networks are overviewed with special attention to applications in intermodulation measurement. It is shown that DFT networks can be used in order to extend the dynamic range of intermodulation measurements. A new lossless DFT network with good isolation properties is proposed. Experimental results at 1.5 GHz frequency show the applicability of DFT networks in multiple-tone intermodulation measurements, when several excitation tones must be suppressed without using highly frequency-selective filtering elements.