Experiments match simulations in a multiple post reentrant cavity

Abstract

Microwave reentrant cavities are used for many applications in science and engineering. The potential for both high mechanical tunability and high electric quality factors make them important tools in many areas. They are usually resonant cylindrical cavities with a central post, which makes a small gap spacing with the cavity wall. By adding an arbitrary number of extra posts, they are generalized to a type of multiple post reentrant cavity. This new approach has been theoretically studied but no experimental results have been presented. The main purpose of this work was to compare experimental modes with simulated ones from a reentrant cavity made of forty nine cylindrical posts. Each post could be moved using a screw in order to make tunable gap spacing between the post top and the cavity cover. Eight different gap setups were made making it possible to investigate thirty six different reentrant modes at room temperature. The lowest frequency percentage agreement between experiment and simulation was 91.31%, and the best one was 99.92%. Taking into account all the modes, 94.44% of them agreed above 96%. Thus, we have determined an experimental procedure suitable to investigate the reentrant modes from multiple post cavities. There is a wide range of potential applications for such cavities due to their unique features compared to conventional ones.

Experimental implementation of a large scale multipost re-entrant array

“…With such structures it is possible to manipulate not only eigenfrequencies of the structure but also field patterns to allow low and high concentration of magnetic fields in small regions that may be useful for many applications 6,33 . Recently it was shown experimentally, that even with a large amount of resonators, finite element analysis could be implemented to understand complicated multiple-resonant structures 34 .…”

“…6,33) Recently it was shown experimentally, that even with a large amount of resonators, finite element analysis could be implemented to understand complicated multiple-resonant structures. 34) To demonstrate possibilities of large scale multi-post cavities experimentally, we implement a 7 by 7 regular square array of posts sharing the same walls as shown in Fig. 1.…”