An Empirical Expression to Predict the Resonant Frequencies of Archimedean Spirals

IEEE Trans Microw Theory Tech. 2015 Jul;63(7):2107-2114. doi: 10.1109/TMTT.2015.2434814. Epub 2015 Jun 3.


This work presents an empirical formula to accurately determine the frequencies of the fundamental and higher order resonances of an Archimedean spiral in a uniform dielectric medium in the absence of a ground plane. The formula is based on method-of-moments simulations which have been experimentally validated. This empirical formula is widely applicable to a broad range of spirals from thin-ring to disk-shaped (ratio of inner to outer radii 0 to 1), with 10 or more turns.

Keywords: High-temperature superconducting (HTS) spiral resonators; nuclear magnetic resonance.