Characterization of Solid-State Nonlinear Transmission Line PCB for RF Production

A discrete-element, printed circuit board (PCB)-based nonlinear transmission line was investigated to characterize its RF output characteristics for varying dc bias current and input pulse voltage. The device demonstrated both forward-wave and backward-wave RF formation, with each mode of operation exhibiting RF frequency and power characteristics. The forward-wave operational mode yielded a wider range of frequency tunability via variation of the applied dc bias. In contrast, the backward-wave operational mode depended more strongly on the input pulse voltage. The forward-wave operational mode generated higher instantaneous RF output power; however, the backward-wave operational mode featured longer RF pulse duration. The backward-wave mode produced consistently higher output frequency, achieving an output frequency of approximately 240 MHz for a 2.5 kV input pulse.

I. Introduction

Nonlinear transmission lines are a unique, vacuum-free high-power microwave (HPM) source technology that achieves HPM production by exploiting the dispersive and nonlinear characteristics of the components and materials used in their construction [1], [2]. NLTLs have taken various forms, ranging from kW to near-GW output power (e.g., [3], [4], [5], [6], [7], respectively), and have achieved frequencies from MHz to multi-GHz [8], [9], [10], [11] and even tens of GHz [12]. NLTLs are especially interesting for their potential to realize an all-solid-state HPM source [13], and have shown promise for their ability to be combined into a phased array [14], [15], thus offering unprecedented modularity and scalability.