A novel real-time Fourier and inverse Fourier transforming system based on non-uniform coupled-line phaser

A novel real-time Fourier and inverse Fourier transforming (RTFaIFT) system realizing both positive and inverse transformations is designed and verified, using non-uniform coupled-line phaser. Two kinds of Fourier transformations are integrated within one system for the first time. This system can map the spectrum of the input signal into a waveform in time domain whose amplitude mimics the spectrum magnitude, owing to the frequency-varying group delay (GD) response of the phaser. Furthermore, the correspondence between the output waveform and the spectrum of the input signal is given for accurate analysis of the spectrum. This configuration possesses the characteristic of compact structure, simple design procedure, and perfect performance, consisting of a mixer, a phaser with linear group delay, a diode, and a LPF. For experimental demonstration, a RTFaIFT system operating at 6 GHz is designed and fabricated, the bandwidth of which is 4 GHz with −0.5 ns/GHz GD slope. Both single- and double-pulse signals have been chosen as the test signals to verify the performance of the RTFaIFT system, respectively. The experimental results agree well with simulation and theoretical results.