Compact Dual-mode Bandpass Filter Research Articles

Dual mode bandpass filter with switchable response

Abstract A compact dual-mode bandpass filter with independently tunable second passband is proposed based on modified V shaped resonators. By switching the pin diodes at each end of the studied resonators, the second passband is independently tuned without affecting the first passband. A prototype of the dual-mode bandpass filter with a dual-passband of 2.54 GHz and 3.36 GHz or a single passband of 2.54 GHz is designed and verified experimentally.

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

PurposeThe purpose of this paper is to present the design of a compact microstrip bandpass filter (BPF) in dual-mode configuration loaded with cross-loop and square ring slots on a square patch resonator for C-band applications.Design/methodology/approachIn the proposed design, the dual-mode response for the filter is realized with two transmission zeros (TZs) by the insertion of a perturbation element at the diagonal corner of the square patch resonator with orthogonal feed lines. Such TZs at the edges of the passband result in better selectivity for the proposed BPF. Moreover, the cross-loop and square ring slots are etched on a square patch resonator to obtain a miniaturized BPF.FindingsThe proposed dual-mode microstrip filter fabricated in RT/duroid 6010 substrate using PCB technology has a measured minimum insertion loss of 1.8 dB and return loss better than 24.5 dB with a fractional bandwidth (FBW) of 6.9%. A compact size of 7.35 × 7.35 mm2 is achieved for the slotted patch resonator-based dual-mode BPF at the center frequency of 4.76 GHz. As compared with the conventional square patch resonator, a size reduction of 61% is achieved with the proposed slotted design. The feasibility of the filter design is confirmed by the good agreement between the measured and simulated responses. The performance of the proposed filter structure is compared with other dual-mode filter works.Originality/valueIn the proposed work, a compact dual-mode BPF is reported with slotted structures. The conventional square patch resonator is deployed with cross-loop and square ring slots to design a dual-mode filter with a square perturbation element at its diagonal corner. The proposed filter exhibits compact size and favorable performance compared to other dual-mode filter works reported in literature. The aforementioned design of the dual-mode BPF at 4.76 GHz is suitable for applications in the lower part of the C-band.

A Compact Dual-Mode Bandpass Filter with High Out-of-Band Suppression Using a Stub-Loaded Resonator Based on the GaAs IPD Process

In this letter, a compact dual-mode bandpass filter (BPF) with an ultra-wide stopband that employs two folded open-loop resonators (FOLRs) and stub-loaded resonators (SLRs) is proposed. The dual-mode resonators are optimized by loading two SLRs onto the folded open-loop resonators, and this process is analyzed using the dual-mode theory. To miniaturize the device size and increase chip performance, the proposed BPF is fabricated by a III–V compound semiconductor-fabrication process using a high-performance GaAs substrate based on the integration passivation device (IPD) fabrication process. A compact dual-mode BPF with low insertion loss and high return loss is designed and fabricated. Two extra transmission zeros (TZs) located in the high-frequency range increase the wide stopband, and the two TZs near the passband result in a higher selectivity. A resonant frequency centered at 7.45 GHz with an insertion loss of −1.21 dB and a measured return loss of higher than −23.53 dB and 3 dB fractional bandwidths of 5.8% are achieved. The stopband can be suppressed up to 20 GHz owing to the two tunable TZs resulting in higher selectivity and wideband rejection. The size of the filter was drastically optimized using a simplified architecture of two FOLRs and SLRs.

Compact dual-mode bandpass filter using defected step-impedance shunt stub

A miniaturized bandpass filter (BPF) using dual-mode defected ground waveguide (DGW) resonator is developed in this letter.The technique with defected step-impedance shunt stub is applied to enhance the self-inductance and self-capacitance of the DGW loop resonator which leads to size reduction. Compared to the conventional design, the central frequency is reduced by 48%. A good agreement between simulation and measurement verifies the validity of this design methodology. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2673–2676, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop26362