Miniaturized bandpass filter using dual-mode hexagonal loop resonator

Abstract

A novel miniaturized dual-mode bandpass filter (BPF) using hexagonal loop resonator is presented. In order to reduce the circuit size, capacitive loading structure is applied to enhance the self-capacitance and electrical length of the hexagonal loop resonator. The frequency selectivity and out-of-band rejection of the proposed BPF can be improved by the two inherent transmission zeros in each side of the passband. Compared with the conventional hexagonal loop resonator without capacitive loading structure, the size of the proposed resonator is reduced by 46.6%. The simulated and measured results are presented and show good agreement.

Compact dual-mode microstrip bandpass filter based on slotted square patch resonator

“…Among the reported resonator structures such as star-shaped ring (Wei and Kewei, 2012), square patch (Yeh et al , 2014; Mezaal et al , 2018; Liu et al , 2019; Cheng et al , 2019; Zhao et al , 2020), octagonal patch (Karthie and Salivahanan, 2019), star-shaped loop (Avinash and Rao, 2017) and hexagonal loop (Song et al , 2017) with different patch/slot as perturbation elements, the proposed square patch resonator with a diagonal square perturbation patch exhibits a compact size of 7.35 × 7.35 mm 2 and a size reduction of 61%, respectively. Amid the filter designs fabricated on RT/duroid 6010 substrate with a relative permittivity of 10.2, the proposed structure offers more miniaturization on the same substrate in addition to the filter designs by Wei and Kewei (2012), Liu et al (2019) and Cheng et al (2019) on different substrates.…”

“…Sharp rejection and high-selectivity BPFs were reported using the dual-mode characteristics of coupled-line resonator structures (Velidi and Sanyal, 2010; Wu et al , 2015; Chen, 2016; Das and Chatterjee, 2019; Afzali et al , 2021; Alnahwi et al , 2021; Mohamadinia et al , 2021). In this context, resonators using ring (Chiou et al , 2010; Feng et al , 2015), loop (Gorur, 2004; Mo et al , 2009; Wu et al , 2012; Song et al , 2017) and slotted patch (Liu et al , 2019; Neeboriya, 2019; Zhao et al , 2020) structures were also realized for the design of planar filters with perturbed configurations to obtain a dual-mode response. However, without using any perturbation element, the design of dual-mode BPF loaded with open stubs has been presented using a ring resonator by Feng et al (2015).…”

“…Meanwhile, with the diagonal square patch as a perturbation element, dual-mode patch resonators by Yeh et al (2014) and Mezaal et al (2018) were reported on a square patch having size reductions of 14.1 and 50%. Several other resonator structures with perturbation elements such as a star-shaped ring with a trapezoidal patch (Wei and Kewei, 2012), hexagonal loop with corner patch (Song et al , 2017) and octagonal fractal patch with a square patch (Karthie and Salivahanan, 2019) were also demonstrated with size reductions of 37, 46.6 and 22%, respectively. Besides, a star-shaped loop resonator structure with triangular patch perturbation (Avinash and Rao, 2017) was also realized with a compact size of 9 × 12 mm 2 .…”

Tunable compact microstrip dual‐band bandpass filter with tapered resonators

“…Compact size, low insertion loss, high attenuation level in the stopband, and sharp roll‐off are the noticeable factors of BPFs designing . Over the last few years, many resonators and filter configurations have been introduced to design high performance BPFs . For example, using ring resonators, different bandpass filters have been designed in Refs.…”

“…In another configuration, hexagonal loop resonators have been employed in Ref. ; however, the filter has complex physical layout. Other topologies used to achieve a wide stopband bandwidth are parallel‐coupled microstrip lines, folded high/low‐impedance open‐ended stubs, and a central semiannular resonator .…”