Magnetless 3-pole Non-reciprocal Bandpass Filter: Numerical Analysis with MATLAB Simulation

Nonreciprocal filters using time-varying transmission lines (TVTL) have recently gained prominence. The basis of their functionality lies in time modulation of space separated resonators using sinusoids having progressive phase shifts. Numerical analysis has been put forward to demonstrate the underlying principles followed by analytical simulations to illustrate the scattering parameters. The purpose of this paper is to analytically formulate and simulate a bandpass filter exhibiting non-reciprocity at the center frequency deploying the concept of time-modulated transmission lines. The periodically loaded resonators in the bandpass filter structure are modulated with sinusoidal signals having progressive phase shifts. The resonators, being separated in space as well as being temporally modulated with signals having progressive phase shifts, the phenomenon is termed as 'spatio-temporal' modulation (STM).