Active Topological Metamaterials with Robust Oscillation Modes

A new type of microwave oscillator arrays based on topological metamaterials is presented. The arrays are built upon a new form of microwave topological insulators consisting of a dual lattice of transmission lines. The proposed structures support extended oscillation modes with remarkable stability against discontinuities and disorder, and arbitrary phase profiles. A comparison with oscillator arrays based on conventional transmission lines is presented, demonstrating a clear superiority for the topological ones. The presented structures create a new direction in the design of microwave oscillator arrays over large areas for applications in phased antenna arrays and time-modulated nonreciprocal devices.