Inset Resonators and Their Applications in Fixed/Reconfigurable Microwave Filters

Widaa, Abdulrahman; Bartlett, Chad; Höft, Michael

doi:10.1109/ims37962.2022.9865311

Cited by 4 publications

(11 citation statements)

References 8 publications

(7 reference statements)

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“…Teflon, Rexolite) and has neither electrical nor mechanical contact with the metallic housing. As shown in [21], the inset resonator configuration has highly desirable advantages in comparison with the conventional half-wavelength and combline structures, including more compactness, better spurious performance, and comparably high Q-factor with the best Q u /volume ratio. As can be seen in Fig.…”

Section: Tunable Inset Resonator Configuration and Operating Principl...mentioning

confidence: 99%

“…This advantageously results in a higher Q-factor for the overall resonator assembly. Furthermore, the sidewall caps are designed to contain the lowest field intensities, therefore, the high Q-factor can be maintained even when there is a close proximity between the resonator and sidewall caps [21]. It is also worth mentioning that in addition to the configuration in Fig.…”

Section: Tunable Inset Resonator Configuration and Operating Principl...mentioning

confidence: 99%

“…Given all these aforementioned limitations and challenges of the various state-of-the-art designs, the introduction of more efficient tuning mechanisms and tunable filter structures is thoroughly required. This work presents new tunable filter designs based on our novel so-called inset resonator configuration which was briefly introduced in [21] for both fixed and tunable filter applications. Compared to the conventional half-wavelength and combline structures, the proposed inset topology advantageously features more compact structures, enhanced spurious performance, and comparably similar Qfactors.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tunable Coaxial Bandpass Filters Based on Inset Resonators

Widaa

Bartlett

Höft

2023

IEEE Trans. Microwave Theory Techn.

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A new class of compact, high-Q, tunable coaxial filters is presented in this paper based on a novel inset resonator concept. The tuning concept is based on the displacement of movable resonators inside a properly modified metallic housing which features wide tuning capabilities and stable high Qfactor performance with minimum variation throughout the tuning window. Various prototypes are designed and implemented to demonstrate and validate the proposed concept. A single tunable inset resonator is first designed and measured showing distinctive results of a 43% tuning range, stable high-Q of 4100±4%, spurious-free band up to 3.8•f0, and volume-saving up to 50% when compared to the conventional combline and halfwavelength structures. The design procedure for constant absolute bandwidth (CABW) tunable filters is then presented, and two different tunable inset filters are designed and implemented. Firstly, a manually tunable four-pole filter is demonstrated with the merits of a wide 39.3% tuning range, while maintaining a constant bandwidth of 116 MHz±6%, and a stable high-Q of 1820±6%. Next, an automatically tunable 3rd-order inset filter is designed and measured using high-accuracy piezomotors. Similarly, the measured results exhibit a wide 1.3 GHz tuning range from 2.65 GHz -3.95 GHz with a stable insertion loss that is less than 0.35 dB, a return loss that is better than 15 dB, and a good spurious performance up to 2.8•f0. To our own knowledge, the proposed tuning technique and tunable components represent state-of-the-art tuning range and stable high-Q with minimal variation when compared with similar loaded-waveguide designs.

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Section: Tunable Inset Resonator Configuration and Operating Principl...mentioning

confidence: 99%

Section: Tunable Inset Resonator Configuration and Operating Principl...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tunable Coaxial Bandpass Filters Based on Inset Resonators

Widaa

Bartlett

Höft

2023

IEEE Trans. Microwave Theory Techn.

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“…For instance, a 4-pole 180 MHz K-band reconfigurable TE 311 waveguide filter was presented in [29] with 1.74% of frequency tuning and a Q factor from 3100 to 2600 using dielectric plates. To this end, coaxial and dielectric-loaded waveguides have gained more interest in many tunable filter applications due to their advantages of miniaturized structures, high Q, and good power handling capabilities [3], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49]. For example, a CABW tunable coaxial filter was reported in [3] for future agile 5G Base Transceiver Stations (BTSs).…”

Section: Introductionmentioning

confidence: 99%

“…The filter operates from 942.5 MHz to 737.5 MHz (24.4%) with a CABW of 23 MHz±8% and a quality factor ranges from 2900 to 2300. Also in [41] and [42], our group recently presented 40% tunable CABW coaxial filters with the least variation of Q factor over the tuning window using inset resonators. To provide more compactness and a higher Q factor than the coaxial filters, a couple of tunable dielectric resonator (DR) filters were proposed [43], [44], [45], [46], [47], [48], [49].…”

Section: Introductionmentioning

confidence: 99%

Widely Tunable TM-Mode Dielectric Filters With Constant Absolute Bandwidth Using Re-Entrant Caps

Widaa

Höft

2023

IEEE J. Microw.

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This paper reports octave tunable dielectric combline bandpass filters with constant absolute bandwidth (CABW) using a novel re-entrant cap tuning technique. The resonant frequency is tuned by the hollow re-entrant cap penetrating into the filter cavity as an envelope around the dielectric resonator. This mechanism of tuning provides wider tuning capabilities and better spurious performance than the conventional screw-based tuning. Also, the cap tuners can be employed effectively to tune the input-output and inter-resonator couplings simultaneously with the frequency reconfiguration, enabling a CABW over a wide frequency tuning window. For proof of concept purposes, a single widely tunable resonator is presented with octave tuning ratio of 2.64:1, high quality factor from 1705 to 5480, and spurious-free band up to 3.44• f 0 . Afterwards, two octave tunable re-entrant cap filters are designed, fabricated, and tested. The first filter is a 78% widely tunable two-pole filter with a CABW of 43.5±12% MHz, low insertion loss equals to 0.28±0.03 dB, and a compact volume of 39 cm 3 . The second design is a four-pole octave tunable bandpass filter from 2.96 GHz to 1.36 GHz with a constant 69±13% MHz bandwidth, low insertion loss better than 0.6 dB, return loss higher than 16 dB, and a compact 62 cm 3 structure. According to our own knowledge, thanks to the proposed tuning mechanism, the presented designs are the first CABW octave tunable high Q waveguide-based filters, having the widest tuning ranges over all similar state-of-the-art-designs. Cap, constant bandwidth, dielectric resonator, high-performance, re-entrant, tunable. INDEX TERMS

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Design of Compact Quasi-Elliptic Bandpass Filters Based on Coaxial Inset Resonators

2023

Self Cite

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This article reports a novel inset resonator configuration for coaxial filter applications with quasi-elliptic responses. The design and analysis of the inset resonator are discussed in detail and accurately modeled as a capacitively-loaded stepped-impedance half-wavelength resonator featuring more compactness, high quality factor, and enhanced spurious responses in comparison with conventional halfwavelength and combline resonators. Additionally, the operating frequency can be tuned intrinsically through the displacement of the coaxial resonator, eliminating the need for any additional tuning elements and maintaining a stable quality factor. Two quasi-elliptic inset resonator type filters are implemented in planar and longitudinal coupling configurations, respectively. The first takes the form of a folded four-pole 2.93 GHz filter with two symmetrical transmission zeros. The fabricated filter has a compact structure of 29.76 cm 3 , an insertion loss better than 0.73 dB, a return loss better than 18 dB, and a wide spurious-free band up to 3.5•f 0 . The second inset-type quasi-elliptic filter is realized in a longitudinal inline arrangement. An example of a 2.53 GHz three-pole filter is presented with a closely-positioned transmission zero, wide spurious-free band (≈3•f 0 ), and a very compact structure of 55.7×33×33 mm 3 .

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Inset Resonators and Their Applications in Fixed/Reconfigurable Microwave Filters

Cited by 4 publications

References 8 publications

Tunable Coaxial Bandpass Filters Based on Inset Resonators

Tunable Coaxial Bandpass Filters Based on Inset Resonators

Widely Tunable TM-Mode Dielectric Filters With Constant Absolute Bandwidth Using Re-Entrant Caps

Design of Compact Quasi-Elliptic Bandpass Filters Based on Coaxial Inset Resonators

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