NONLINEAR TRANSMISSION LINES FOR HIGH POWER MICROWAVE APPLICATIONS - A SURVEY

Nonlinear transmission lines (NLTLs) have been used successfully to produce high power microwave (HPM) oscillators over the past 20 years. The advantages of such devices include compact structures in a narrow band radiator, frequency agility, and relatively high power. The key component in such devices is the nonlinear material used in the transmission line (TL). Attempts have been made using both nonlinear dielectrics and magnetic materials in NLTLs, with magnetic materials producing the biggest successes, to-date. This paper presents an overview of the work that has been done to-date in NLTLs with an emphasis on the body of knowledge directly applicable to HPM. A brief summary of the documented efforts using both dielectric and magnetic materials will be offered. Then, the authors present their analysis of what is needed to make further progress along the path towards higher power devices. This paper presents a roadmap for research deemed necessary from an engineering point-of-view to accomplish this goal. In particular, the need for characterizing such materials and building proposed testbeds for accomplishing this goal will be discussed. Finally. we will discuss a third design option - a hybrid approach that combines the features of nonlinear dielectrics and nonlinear magnetic materials for the purpose of producing robust RPM oscillators.