Improving the Frequency Response of a Circular Dual-Mode Resonator with a Reconfigurable Bandwidth

Authors: Muhammad Haitham Albahnassi, Adnan Malki, Shokri Almekdad

Abstract:

In this paper, a method for reconfiguring bandwidth in a circular dual-mode resonator is presented. The method concerns the optimized geometry of a structure that may be used to host the tuning elements, which are typically RF (Radio Frequency) switches. The tuning elements themselves, and their performance during tuning, are not the focus of this paper. The designed resonator is able to reconfigure its fractional bandwidth by adjusting the inter-coupling level between the degenerate modes, while at the same time improving its response by adjusting the external-coupling level and keeping the center frequency fixed. The inter-coupling level has been adjusted by changing the dimensions of the perturbation element, while the external-coupling level has been adjusted by changing one of the feeder dimensions. The design was arrived at via optimization. Agreeing simulation and measurement results of the designed and implemented filters showed good improvements in return loss values and the stability of the center frequency.

Keywords: Dual-mode resonators, perturbation element, perturbation theory, reconfigurable filters, software defined radio (SDR), cognitine radio.

Digital Object Identifier (DOI): doi.org/1

References:

[1] Christian Schuster ; Alex Wiens ; Florian Schmidt ; Matthias Nickel ; Martin Schüßler ; Rolf Jakoby ; Holger maune” Performance Analysis Of Reconfigurable Bandpass Filters With Continuously Tunable Center Frequency And Bandwidth”, IEEE Transactions on Microwave Theory and Techniques ,Vol: 65 , Issue: 11, pp.4572-4583 , Nov. 2017.
[2] Pingyue Song; Hossein Hashemi A 13th-order CMOS reconfigurable RF BPF with adjustable transmission zeros for SAW-less SDR receivers” IEEE International Solid - State Circuits Conference - (ISSCC) March 2018.
[3] Adham Naji, Paul Warr, Mark Beach and Kevin Morris, “A Fundamental Limit on the Performance of Geometrically-Tuned Planar Resonators”, IEEE Transactions of Microwave Theory and Techniques, Vol. 59, Iss. 6, pp. 1491-1499,2011.
[4] Ali Kursad Gorur, Pinar Ozturk Ozdemir, Elif Gunturkun Sahin, Ceyhun Karpuz2 "A novel microstrip diplexer design with tunable bandwidths and switchable channels for 4.5G applications," Turkish Journal of Electrical Engineering & Computer Science, vol. 25, pp 4445- 4456,Aug 2017.
[5] Cesar A. Lugo Jr., “Design and synthesis techniques for reconfigurable microwave filters using single and dual mode resonators”,PhD dissertation, Georgia Institute of Technology, December 2006.
[6] J.-S. Hong,"Coupling of asynchronously tuned coupled microwave resonators", IEE Proc. Microw. Antennas Propag., Vol. 147, pp. 354-358, 2000.
[7] Jia-Sheng Hong, “Microstrip Filters for RF/Microwave Applications”, 2nd edition, Wiley, 2011
[8] Adham Naji; and Mina H. Soliman "Center Frequency Stabilization in Planar Dual-Mode Resonators during Mode-Splitting Control", Scientific Reports, pp 1-14 Vol 7, March 2017.
[9] https://imageserv11.team-logic.com/mediaLibrary/303/25N25FR.pdf
[10] Adham Naji and Paul Warr, “Independence of the unloaded Q of a Planar Electromagnetic Resonator from its Shape”, IEEE Transactions on Microwave Theory and Techniques, Vol. 60, Iss. 8, pp. 2370-2377.2012