Lightweight Low-Profile Highly-Efficient Magnetless Isolator Comprising Two Time-Modulated Loops

We propose a lightweight compact highly efficient non-magnetic time-modulated isolator based on signal interference in phase-shifted time-modulated loops. The proposed isolator exhibits large isolation level and weak undesired time harmonics. In contrast to the recently proposed space-time-modulated isolators which are governed by progressive unidirectional coupling between the incident wave and the modulation, our isolator is not governed by such a progressive process and therefore possesses a very low-profile. An experimental demonstration of the proposed time-modulated isolator at microwave frequencies is provided, showing strong unidirectional wave transmission through the isolator with more than 27 dB contrast between the forward and backward waves.