Experimental measurement of W-band backward-wave amplification driven by external pulsed signals

The experimental implementation of W-band backward-wave oscillator is achieved by using a multilevel microfabrication of interaction circuit including beam tunnel, slow-wave structure, and output transition, on deep reactive ion etched (DRIE) and metal deposited silicon wafers. The interaction circuit shows precise accuracy in full 3 dimensions, and the return loss measurement agrees well with HFSS simulation. Here we describe the experimental observation of W-band backward-wave oscillation and amplification after successful vacuum-sealed integration of interaction circuit, electron gun, beam collector, and output window.