Daotong Li

NOVEL DESIGN OF A COMPACT TRIPLE-BAND BANDPASS FILTER USING SHORT STUB-LOADED SIRS AND EMBEDDED SIRS STRUCTURE

A novel compact planar triple-band bandpass fllter using two sets of short stub-loaded stepped impedance resonators (SSLSIRs) and a pair of embedded stepped impedance resonators (ESIRs) has been proposed. The SSLSIRs can adjust the bandwidths of the corresponding passbands over a wide range, and the ESIRs employing non 0 - -feed coupled structure with mixed electric and magnetic coupling can obtain an extra transmission zero. The embedded resonators structure can further miniaturize the dimensions of the whole triple-band fllter. The operating frequencies of the SSLSIRs and ESIRs are designed for the applications of the WLAN (2.45/5.2GHz) and WiMAX (3.5GHz) systems, respectively. The simulated and measured results are both presented and show good agreement.

Miniaturized Quint-Band Bandpass Filter Based on Multi-Mode Resonator and

Based on multi-mode resonator (MMR) and λ/4 resonators, a miniaturized microstrip quint-band bandpass filter (BPF) with mixed electric and magnetic coupling (MEMC) has been presented. The proposed MMR is employed to generate the 1st, 2nd, and 5th passbands, while the 3rd and 4th ones of close band proximity are achieved by using four coupled λ/4 uniform impedance resonators (UIRs). Due to MEMC cancelling effect, virtual grounds in feed lines, and source-load cross coupling, multiple transmission zeros (TZs) can be yielded to obtain sharp passband roll-off skirts. To verify the validity of the design approach, a quint-band BPF centering at 2.1, 3.0, 4.0, 4.7, and 7.2 GHz (denoted as f1, f2, f3, f4, and f5) with respective 3 dB fractional bandwidths of 13.7%, 5.6%, 10.5%, 5.1%, and 2.9% has been designed and fabricated, whose measured results show good consistence with the predicted frequency responses.

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Abstract Based on a short stub-loaded stepped-impedance resonator, a novel compact microstrip bandpass filter with controllable passband center frequencies is presented. To obtain dual-passband characteristics, dual-mode short stub-loaded stepped-impedance resonator and novel quad-pole-splitting techniques are investigated. The single passband is split into two with a notch when two resonators are employed, and dual passbands of a close band could be realized. It was found that the filter exhibits two desirable close passbands, an adjustable fractional bandwidth, and wide upper-stopband response. Moreover, the compact size of the proposed structure can be achieved. Good agreement between the measured and simulated results is shown.

Resonators With Mixed Electric and Magnetic Coupling

This paper presents a compact UWB BPF with a notch band using a novel quadruple-mode resonator and spur-lines. The characteristics of quadruple-mode resonator are investigated by using the odd- and even-mode analysis method. In the design, the resonator is excited by using interdigital-coupled-lines. When the spur-lines are introduced, a notch band with controllable center frequency can be achieved in the passband. Good agreement between the measured and simulated results was shown.

Miniaturized Close Dual-Band Bandpass Filter Based on Short Stub-Loaded Stepped-Impedance Resonators

A compact dual-wideband bandpass filter featuring two controllable center frequencies and passbands using a single side-coupled shorted λ/4 stepped-impedance resonator (SIR) is presented. The resonant frequencies of the two passbands can be adjusted by tuning the impedance ratio and length of the SIR. The bandwidth of the two passbands is determined by the coupling strength between the meandering feedlines and the resonator. The generation mechanism of filter’s transmission zeroes was investigated by equivalent models of the filter and the bending parts of the open-end meandering feedlines. Owing to the cross-coupling between the two open-end meandering feedlines and the phase shifted characteristic of the open-end meandering feedlines, several transmission zeroes can be generated to improve the selectivity. To verify the design concept, one dual-wideband bandpass filter has been designed, fabricated, and measured. The simulated and measured results are presented with good agreement.

A novel design of UWB bandpass filter with notch band

A quadruple-mode resonator based on stub-loaded was proposed. The resonator possesses four resonances over the wide frequency band from 3.1-10.6 GHz, which can be employed to implement an ultra-wideband bandpass filter(BPF) to achieve flat response. The quadruple-mode resonator is investigated by using odd-even mode analysis and weak coupling method. Two transmission zeroes are located at the upper and lower stopband which improve the selectivity of the UWB BPF. The six transmission poles in passband are created by the quadruple modes resonator and the interdigital coupled feedlines. For verification, a UWB BPF is designed, fabricated and measured. Good agreement is observed between measured and simulated results.

Compact dual-wideband bandpass filter with good selectivity using side-coupled λ/4 shorted SIR

A compact dual-wideband bandpass filter (BPF) is proposed by using dual-stubs loaded λ/2 resonator (DSLR). The resonance of the DSLR is investigated by using the even-/odd-mode analysis method. As the length of the stubs increases, the second and third resonant frequencies are coalesced. So when the DSLR is employed to design a dual-band BPF, the first three resonant frequencies are used to build up the first passband, and the fourth and fifth resonant frequencies will form the second passband. Meanwhile, the two passbands can be adjusted by tuning the parameters of the DSLR. To verify the design concept, one dual-wideband BPF has been designed, fabricated, and measured. Good agreement is observed between measured and simulated results.