Dual-mode Open-loop Resonator Research Articles

Multitransmission Zero Dual-Band Bandpass Filter Using Nonresonating Node for 5G Millimetre-Wave Application

A planer millimetre-wave dual-band bandpass filter with multitransmission zeros is proposed for 5G application. This filter includes two dual-mode open-loop resonators. The U-shape nonresonating node is employed to generate an extra coupling path. Finally, a dual-band bandpass filter with five transmission zeros is obtained. The filter is fabricated and measured. Good agreement between simulation and measurement is obtained.

High selectivity tunable filtering power divider based on liquid crystal technology for microwave applications

A novel electrically tunable filtering power divider, based on liquid crystal (LC) technology, is designed and experimentally demonstrated in this paper. Using low-cost T-shaped inverted-microstrip structures integrated with two dual-mode open-loop resonators, the tunable power divider possesses bandpass-filtering frequency response. Moreover, transitions between inverted-microstrip and microstrip structures are specifically designed at the I/O ports for the self-packaged. The experimental results indicate that the central frequency can be tuned from 5.75 to 6.25 GHz, i.e. a relative tuning range of 8.3%, the 3-dB bandwidth is 6.8 ± 0.2% over the whole tuning range, and the maximum amplitude and phase imbalance are less than 0.8 dB and 2.5°, respectively. In addition, the proposed filtering power divider has three transmission zeros to improve the frequency selectivity.

Design of Narrowband Band Pass Filter using Open-loop Square Resonators with Loading Element

Objectives: In this paper we propose to design a compact, sharp-rejection narrowband BandPass Filter (BPF). Methods/Statistical Analysis: The behavior of the microstrip open-loop resonator is observed using full-wave electromagnetic simulations. By adding a loading element at the center of the open loop square resonator we are achieving two operating modes (even and odd modes) exist within a single resonator. Variation of parameters of the loading element leads to asymmetric frequency response used for filter design. The simulated results met all the design specifications of the given band pass filter. Findings: In the dual-mode open loop resonator the even and odd modes (currents are mutually exclusive in nature) do not couple each other and leads to a rejection point in the frequency, which is associated with the even mode. Multiple sections of resonator give the sharp rejection (high dynamic range) after the passband. Application/Improvements: The proposed band pass filter can be widely used in communication system and space technology, especially mobile and satellite communication due to its better performance and compactness.

Compact Multi-Band Bandpass Filters With Mixed Electric and Magnetic Coupling Using Multiple-Mode Resonator

In this paper, a multiple stubs loaded ring resonator (MSLRR) is proposed to design directly coupled multi-band bandpass filters (BPFs) with mixed electric and magnetic coupling (MEMC). The proposed MSLRR exhibits multiple-mode resonant behavior. The increased number of loaded stubs excite many more useful resonant modes, but these resonant modes can be still independently controlled. As examples, a dual-band BPF, a tri-band BPF, a quad-band BPF, and a quint-band BPF using different types of MSLRRs are designed and fabricated. The passband frequencies and return losses (RLs) of these multi-band BPFs can be independently controlled. A dual-mode open loop resonator is then introduced in the quint-band BPF to enhance the sixth resonant mode of the MSLRR to produce the sixth passband so that a sext-band BPF is also presented. Multiple transmission zeros due to the cancelling effect of MEMC and virtual grounds in the MSLRR can be observed around the passbands resulting in sharp passband selectivity and high band-to-band isolation. Moreover, all of the fabricated multi-band BPFs have compact sizes, good RLs, and low insertion losses. Good agreements are observed between the simulated and measured results.

Dual‐mode dual‐band bandpass filters design using open‐loop slotline resonators

A dual-mode open-loop slotline resonator with a centre-loaded stub is proposed. The loaded stub is used to excite non-degenerate modes, that is, the even and odd modes. Distinct characteristics of this dual-mode resonator are investigated by using even–odd mode analysis. Also, equivalent circuit models for non-degenerate modes are given to determine the resonance conditions and the location of transmission zero. Then, two novel approaches for designing dual-mode dual-band bandpass filters are presented. One approach consists of simple microstrip feedlines and two embedded open-loop slotline resonators for single substrate configuration. The other is composed by using dual-mode open-loop resonators in the form of microstrip and slotline structures on a single substrate. A microstrip invert L-shape feeding structure is employed to simultaneously feed the microstrip and slotline resonator on different layers for broadside coupling. Both of them provide sufficient degrees of freedom to control the centre frequencies and fractional bandwidths of both passbands independently. The two filters are designed, fabricated and measured. A good agreement between the simulation and measurement verifies the validity of this design methodology.

Dual-mode dual-band bandpass filter design using open-loop resonators

This letter presents a novel dual-band bandpass filter using dual-mode open-loop resonator. Non-degenerate modes of the dual-mode resonator are excited by loading a center-loaded T-shaped stub and its nature is investigated through the even-odd mode analysis. Based on the aforementioned dual-mode resonators, a compact dual-band filter is designed. Results verify that the fabricated filter with the central frequencies of 1.8 and 2.4 GHz and the fractional bandwidth of 8.3 and 12.9% are obtained. Also, there are several transmission zeros located at both sides of each passband. It provides the filter with improved selectivity and stopband suppression. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2370–2372, 2012; View this article online at wileyonlinelibrary.com.. DOI 10.1002/mop.27080

DESIGN OF OPEN-LOOP DUAL-MODE MICROSTRIP FILTERS

This paper presents the design of compact second-order bandpass ¯lters based on dual-mode open-loop resonator. A ¯lter design procedure is provided to facilitate the design process. The paper also describes the nature of the inherent transmission zero associated with the structure and presents a method of generating two additional zeros for improving stop-band performance. Finally, a ¯lter design example is presented to validate the argument.

Electronically Reconfigurable Dual-ModeMicrostrip Open-Loop Resonator Filter

A new type of reconfigurable asymmetric frequency response bandpass filter using dual-mode open-loop resonator is investigated. It explores the unique characteristic of the dual-mode open-loop resonator whose two operating modes, i.e., the even- and odd-modes do not couple. Thus, tuning the passband frequency is accomplished by merely changing the two modal frequencies proportionally, which makes the electronic tuning simple. Furthermore, for a single filter of this type, its selectivity can be electronically reconfigured to exhibit a higher selectivity with a finite-frequency transmission zero on either side of the passband. For the demonstration, both simulated and measured results are presented.

Novel miniaturized open-square-loop resonator with inner split rings loading

The adoption of flower rings coupled with inner split rings within an open-square-loop resonator for size miniaturization is first analyzed and designed. To demonstrate the proposed technique of loading, a novel dual-mode open-loop resonator operating at 2.5 GHz is next designed. The proposed technique of perturbation achieves a 48.4% loading factor for the resonators. The proposed resonator is 2.94% smaller in area as compared to the meander loop resonator, and 5.5% smaller in area as compared to the hairpin resonator. Harmonic suppression is also easily achieved through the integration of these circular rings.