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Open AccessArticle

Demonstration of Reconfigurable BPFs with Wide Tuning Bandwidth Range Using 3λ/4 Open- and λ/2 Short- Ended Stubs

1
Frederick Research Center, Frederick University, Nicosia 1036, Cyprus
2
Department of Electrical & Computer Engineering, University of Cyprus, Nicosia 1678, Cyprus
*
Authors to whom correspondence should be addressed.
This paper is an extended version of our paper published in the 8th International Conference on Modern Circuits and Systems Technologies (MOCAST), Thessaloniki, Greece, 13–15 May 2019.
Technologies 2020, 8(1), 14; https://doi.org/10.3390/technologies8010014
Received: 16 December 2019 / Revised: 20 January 2020 / Accepted: 1 February 2020 / Published: 3 February 2020
In this paper, two implementations of reconfigurable bandwidth bandpass filters (BPFs) are demonstrated both operating at a fixed center frequency of 2.4 GHz. The proposed reconfigurable bandwidth filters are based on a square ring resonator loaded with λg/4 open-ended stubs that are permanently connected to the ring and converted to either 3λg/4 open-ended stubs or λg/2 short-ended stubs by means of positive-intrinsic-negative(PIN) diodes to implement two reconfigurable bandwidth states for each case. Due to the symmetrical nature of the design, even- and odd-mode analysis is used to derive the closed-form to describe the reconfigurable filters’ behavior. The switching between narrowband and wideband is achieved using PIN diodes. In the first implementation (λg/4 open-ended stubs to 3λg/4 open-ended stubs), a reconfigurable bandwidth bandpass filter is proposed where additional out-of-band transmission zeros are generated by integrating a λg/2 open-ended stub at the input port. In the second implementation (λg/4 open-ended stubs to λg/2 short-ended stubs), further improvement in the upper stopband is achieved by utilizing a pair of parallel coupled lines (PCLs) as feeding lines and a pair of λg/4 high impedance short-ended stubs implemented at the input and output ports. To verify the validity of the simulated results, the prototypes of the proposed reconfigurable filters were fabricated. For the first case, measured insertion loss is less than 1.8 dB with a switchable 3-dB fractional bandwidth (FBW) range from 28% to 54%. The measured results for the second case exhibit a low insertion loss of less than 1 dB and a 3-dB fractional bandwidth that can be switched from 34% to 75%, while the center frequency is kept constant at 2.4 GHz in both cases. View Full-Text
Keywords: bandpass filter; PIN diode; reconfigurable bandwidth bandpass filter; PIN diode; reconfigurable bandwidth
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Arain, S.; Quddious, A.; Nikolaou, S.; Vryonides, P. Demonstration of Reconfigurable BPFs with Wide Tuning Bandwidth Range Using 3λ/4 Open- and λ/2 Short- Ended Stubs. Technologies 2020, 8, 14.

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