title: Center Frequency Stabilization in Planar Dual-Mode Resonators during Mode-Splitting Control.
abstract: Shape symmetry in dual-mode planar electromagnetic resonators results in their ability to host two degenerate resonant modes. As the designer enforces a controllable break in the symmetry, the degeneracy is removed and the two modes couple, exchanging energy and elevating the resonator into its desirable second-order resonance operation. The amount of coupling is controlled by the degree of asymmetry introduced. However, this mode coupling (or splitting) usually comes at a price. The centre frequency of the perturbed resonator is inadvertently drifted from its original value prior to coupling. Maintaining centre frequency stability during mode splitting is a nontrivial geometric design problem. In this paper, we analyse the problem and propose a novel method to compensate for this frequency drift, based on field analysis and perturbation theory, and we validate the solution through a practical design example and measurements. The analytical method used works accurately within the perturbational limit. It may also be used as a starting point for further numerical optimization algorithms, reducing the required computational time during design, when larger perturbations are made to the resonator. In addition to enabling the novel design example presented, it is hoped that the findings will inspire akin designs for other resonator shapes, in different disciplines and applications.
authors.affiliation: Electrical Engineering Department and Centre for Theoretical Physics, The British University in Egypt, El-Sherouk, Cairo, 11837, Egypt.|Electrical and Electronic Engineering Department, University of Bristol, Bristol, BS8 1UB, UK.
authors.forename: Adham
authors.initials: A
authors.lastname: Naji
authors.affiliation: Electrical Engineering Department and Centre for Theoretical Physics, The British University in Egypt, El-Sherouk, Cairo, 11837, Egypt.|Department of Information Technology and Electrical Engineering, Swiss Federal Institute of Technology (ETH Zurich), Zurich, 8092, Switzerland.
authors.forename: Mina H
authors.initials: MH
authors.lastname: Soliman