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.
Highlights
Ω, and I is the current source at the network’s terminals)
It is important to note that this study is concerned with the frequency symmetry at the fundamental level of single dual-mode resonator design, not at the higher level of filter design, where N such resonators may be coupled together in a system and where overall frequency symmetry may be afforded by manipulating coupling configurations at the higher system level
If the designer wishes to keep the center frequency, fc, of the system fixed during the tuning, the designer will have to devise a mechanism to compensate for the drift incurred in fc due to the tuning of f1 and f2
Summary
Ω, and I is the current source at the network’s terminals). This would be a desirable practical feature when the resonator is connected to other matching networks or resonators within a larger system. It is important to note that the term planar here implies no field variations along substrate depth (along z, say), which is much smaller a dimension compared to the resonant wavelength. To find a solution to this problem, one must first understand the different types of effects that a disturbance can cause in a dual-mode resonator. By analysing these effects and the different phenomena related to them, one can deduce possible mechanisms that can support tuning the mode-coupling while maintaining the center frequency unchanged. Without loss of generality, we base the following discussion and analysis on square dual-mode planar resonators, such as that shown, and demonstrate a novel solution example in the microwave regime. The treatment can be extended to other types of structures and frequency regimes, following similar lines of analysis
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
