Development of a Dual Mode, Variable Volume Resonant Cavity System

Abstract

A cavity system capable of producing independent electric and magnetic fields by the simultaneous excitation of two indepen­ dent cavity modes has been built and tested. The cavity length was made adjustable by a novel mechanical design which allowed an end plate to be accurately positioned at the desired length. The adjustable length provided the flexibility to selectively excite higher order cavity modes without building a new cavity for each mode. In addition, a mechanical design is set forth for a cavity whose cross sectional dimensions as well as length can be varied. space. This can present interference problems and radiation hazards. High strength electromagnetic fields above around 50 MHz can potentially couple very strongly to objects the size of humans;4,5 this could be hazardous to laboratory personnel. Considering the above, it is felt that a different approach to simulating complex electromagnetic fields is needed. The analysis presented in this paper indicates that a resonant cavity system is feasible. A resonant cavity system can provide (1) a very efficient conversion of source power to high intensity fields, and (2) in­ dependent electric and magnetic fields by the simultaneous excita­ tion o f two independent cavity modes. Other major advantages o f a cavity system are: