Quadruple-mode Resonator Research Articles

Single-wideband and dual-band bandpass filters based on compact quadruple-mode resonator

A stub-loaded U-shaped microstrip resonator (U-SLR) exciting two odd-modes and two even-modes and its applications to single-wideband and dual-band bandpass filter (DB-BPF) are introduced. The parallel-coupled lines (PCLs) at input/output (I/O) ports can provide a wideband response by exciting two additional modes in the passband, so-called PCLs modes. In addition to the transmission poles (TPs) in the passband, two transmission zeros (TZs) in the lower and upper stopbands can be created by the loaded stubs. A compact size, high-selectivity, and low insertion loss WB-BPF is designed, fabricated, and tested. Moreover, a compact and low loss DB-BPF with closely spaced passbands is designed and tested. TZ-shifting method is used to design a DB-BPF by splitting the wideband. To achieve this, it is sufficient to change the length of only one of the loaded stubs. The calculated, simulated and measured frequency responses for both single-wideband and DB-BPFs are in very good agreement.

Two-Way Waveguide Diplexer and Its Application to Diplexing In-Band Full-Duplex Antenna

A design of a diplexing in-band full-duplex (IBFD) slot antenna based on the quadruple-mode resonator (QMR) is presented for the first time. First, a two-way waveguide diplexer integration using QMR is designed. Four waveguide modes, namely, TE011, TE101, TM210, and TM120, are primarily used. These four modes are modal orthogonal to each other in a single QMR. Each of the quadruple modes can be independently manipulated with low mutual interference with other modes. Taking advantage of this characteristic, a two-way waveguide diplexer integration can be implemented with four independent frequency channels. In each diplexer, the downlink channel is dominated by fundamental mode TE011/TE101, while the uplink channel is dominated by high-order mode TM210/TM120. By cascading QMRs, higher order frequency responses are achieved with expected coupling coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> ) and external quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q_{{\text {e}}}$ </tex-math></inline-formula> ). Based on the proposed two-way diplexer concept, a diplexing IBFD antenna with a turnstile junction is designed by replacing the inputs with a cross-coupled radiating slot. It integrates the filtering, diplexing, orthomode transducing, and radiating functions into a single element. Four channels can work independently to transmit/receive two orthogonal signals. The two-way waveguide diplexer and diplexing IBFD waveguide antenna with a second-order response were implemented and tested for the proof-of-concept.

Tapered rainbow metabeam for wideband multimode acoustic blocking based on quadruple-mode resonators

We construct a rainbow metamaterial for multimode sound blocking over a broad range of sub-kHz frequencies in the form of a tapered rectangular cross section beam of machined cells based on elements that can, on average, simultaneously attenuate the majority of the possible elastic-wave polarizations. Using aluminum, we construct a five-cell structure containing sub-wavelength planar resonators with interconnected ribs, which couple to compressional, in-plane shear, flexural, and torsional vibrations. Backed up by numerical simulations, we verify that this tapered structure can, on average, strongly attenuate acoustic modes over the frequency range of the combined metamaterial bandgaps, that is over a frequency range representing ∼50% around ∼0.7 kHz. Applications include vibration isolation.

A compact balanced filter with quadruple-mode resonators for UWB application

A compact ultra-wideband (UWB) balanced bandpass filter (BPF) with quadruple-mode resonators on a microstrip line is proposed. The circuit of the proposed filter is analyzed, and it is shown that the differential-mode circuit performs as a UWB BPF, while the common-mode circuit performs as a UWB bandstop filter (BSF). The differential-mode circuit consists of two short-circuited stubs that are properly attached to the initial multiple-mode resonator (MMR) to form a quadruple-mode UWB BPF. Having a highly-attenuated wide upper-stopband in the frequency response of the differential-mode operation is a significant feature for this circuit. By installing two pairs of open-circuited stubs in the symmetrical line, the differential-mode frequency response remains unchanged but its common-mode frequency response is reshaped to achieve the stopband in the overall UWB. Finally, a microstrip UWB balanced BPF is designed, simulated and measured. Simulated and measured results are in good agreement with each other, showing that the proposed filter has compact size, UWB differential passband (3dB fractional bandwidth 113%) and UWB common-mode suppression (12dB attenuation across 3.3–12.4 GHz).

Design of Filtering Crossover and Diplexer on SIW Quadruple-Mode Resonators in a Single Cavity

This paper at first presents the proposal and design of a filtering crossover and diplexer with two second-order filtering channels on substrate integrated waveguide (SIW) quadruple-mode resonators (QMRs) and in single cavities. The proposed method has an interesting application in the overall size miniaturization design. The proposed resonator is yielded with four perturbed modes (TE103, TE104, TE201 and TE202) featuring distinct electric field distributions by inserting metal via-holes in the center of a rectangular SIW cavity. Next, a pair of resonances is applied to form a second-order filter channel while TE201 and TE202 modes are implemented to realize the other, thereby integrating the whole circuit in a single cavity. Besides, the transmission responses between the channels are isolated only by the perturbed via-holes. Slots are introduced in the metal surface to further increase each channel design flexibility. In this way, controllable frequencies and compact size have been well achieved. Two examples including a crossover and diplexer with two second-order filter channels are designed, fabricated, and measured to verify. Good agreement between simulation and measurement can be observed.

Dual-Plane Quadruplexer Using Common Lumped-Element Quadruple-Mode Resonator

This letter presents a 0.43 GHz/0.9 GHz/1.575 GHz/ 2.45 GHz quadruplexer with ripple bandwidth of 40 MHz/ 70 MHz/60 MHz/100 MHz using a common lumped-element quadruple-mode resonator (LE-QMR). One resonant mode from LE-QMR and two resonant modes from two $LC$ resonators constitute every channel of the proposed quadruplexer. The dual-plane structure configuration is employed in this design to relieve the limited physical space. A step-to-step design procedure is given to validate our design approach. The measured result shows that the fabricated quadruplexer exhibits low insertion loss, up to 40-dB port-to-port isolation and compact size of $0.071\lambda _{g}\times 0.097\lambda _{g}\times 0.002\lambda _{g}$ .

Perfect acoustic bandgap metabeam based on a quadruple-mode resonator array

Solid structures guide a multitude of elastic modes of different polarizations including both compression and shear, and the nature of the elastic constant tensor implies a much richer behavior than in optics. Here, we introduce a metamaterial in the form of a rectangular cross section beam of a single isotropic material that can simultaneously suppress all elastic-wave polarizations in the beam over a range of frequencies in the kHz range. This is experimentally achieved by machining replicas of a subwavelength unit cell in an aluminum metabeam based on a planar resonator with interconnected ribs, showing complex vibrational degrees of freedom that allow it to couple to compressional, in-plane shear, flexural and torsional vibrations, that is, all four existing mode types. The result is a lightweight structure that can forbid all possible acoustic modes over the metamaterial bandgap frequency range, an exotic behavior that opens up diverse applications in easily manufacturable vibration isolation structures and acoustic wave control.

Compact superconducting single- and dual-band filter design using multimode stepped-impedance resonator**Project supported by the National Natural Science Foundation of China (Grant No. 61371009) and the Fund from the Chinese Ministry of Science and Technology (Grant No. 2014AA032703).

This study presents two multimode stepped-impedance structures to design single- and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The single-band filter with high selectivity is centered at 6.02 GHz and has a fractional bandwidth (FBW) of 25.6%. Four stubs (two low frequency and two high frequency ones) are connected to the rectangular patch in the center to construct a quadruplemode resonator. The independent conditions of the center frequencies of the high and low bands of the resonator are analyzed. A dual-band filter, which operates at 1.53 GHz and 2.44 GHz with FWBs of 12.1% and 14.1%, respectively is designed. The single- and dual-band filters are both fabricated with double-sided YBCO films and they can be used in mobile and satellite communications.

Wideband BPF using quadruple-mode ring resonator loaded with short-circuited stubs and Γ-shaped band-stop sections

Wideband BPF using quadruple-mode ring resonator loaded with short-circuited stubs and Γ-shaped band-stop sections

Wideband balun bandpass filter explored for a balanced dipole antenna with high selectivity

A novel microstrip wideband balun bandpass filter (BPF) is presented for development of a balanced dipole antenna with wide operating band and high frequency selectivity. By utilising the standing-wave property of current distribution along a half-wavelength (λ/2) open-ended microstrip line, out-of-phase signals are ideally obtained at two output ports of a balun. Meanwhile, proper coupling topologies between the open-circuited λ/2 microstrip transmission line and the quadruple-mode resonators are selected to achieve a balun BPF with both characteristics of balanced performance and wideband filtering properties. A balun BPF operating at 1.65 GHz with 32% fractional bandwidth is at first designed. The derived results not only exhibit good performance with 0.49 dB amplitude imbalance and 7.2° phase imbalance, but also achieve high selectivity relying on two transmission zeros. Next, this balun BPF is integrated with a balanced dipole antenna with a flat shape towards wideband and high-selective radiation. Both simulated and measured results achieve higher than 10 dB return loss and 2.4 dBi radiation gain over a band of 1.4–1.9 GHz.

Self‐packaged SISL dual‐band BPF using a new quadruple‐mode resonator

A new quadruple-mode resonator (QMR) is proposed to design a self-packaged dual-band bandpass filter (DBBPF) by using the substrate integrated suspended line (SISL) technology. The low insertion losses of the fabricated DBBPF are 0.52/1.76 dB and the fractional bandwidth are 65.4%/9.2% for two operation passbands at 2.65/8.71 GHz, respectively. The measured results are in good agreement with electromagnetic simulation.

Quad-Band Bandpass Filter Using Quad-Mode Stub-loaded Resonators

Compact multi-band bandpass filters using quad-mode stub-loaded resonators are proposed in this letter. Firstly, a novel approach about the mode-splitting characteristics of the quadruple-mode resonator is investigated, which can provide dual-band behavior. Secondly, a quad-band filter is proposed and designed by cascading two quadruple-mode resonators; the upper one operates at 1.8/2.4 GHz (GSM- and WiMax-band) and the lower one at 1.57/2.1 GHz (GPS- and WCDMA-band). Finally, the proposed filters have been fabricated. Respectable agreement between simulation and measurement verifies the validity of this design methodology.

Dual-Band Superconducting Bandpass Filter Using Quadruple-Mode Resonator

A dual-band high-temperature superconducting (HTS) bandpass filter (BPF) using a quadruple-mode resonator is realized in this paper. The resonator consists of a half-wavelength uniform impedance resonator, an open stub in a symmetrical plane, and two spiral open stubs at the two sides of the symmetrical plane. Distinct characteristics of the quadruple-mode resonator are investigated by using even/odd mode theory, and the design graphs are given to analyze the dual-band filter. A dual-band HTS BPF with central frequencies of 1.8 GHz for GSM applications and 2.4 GHz for wireless local area network applications is designed using the proposed quadruple-mode resonator, which is fabricated by depositing YBCO films on a 0.5-mm-thick MgO substrate. Its size occupies only 13 mm × 17 mm. Measured results demonstrate that an insertion loss within the passbands is less than 0.25 dB. In addition, a transmission zero is achieved in-between two passbands, and two transmission zeros are realized in the upper stopband of the higher passband, which improve the skirt selectivity and stopband characteristics of the filter.

Compact quadruple‐mode resonator for wideband bandpass filter design

This study presents the realisation of a wideband bandpass filter using a novel compact quadruple-mode resonator. The quadruple-mode resonator, which is evolved from the square open-loop resonator, is an interesting structure for a compact design. The resonator has two odd and two even mode resonant frequencies whose approximate analytical expressions are derived. For a wide bandwidth filter, three short branch-lines are introduced to the resonator in order to widen the separation between the resonant frequencies. A filter with a 3 dB fractional bandwidth of 96.0% is demonstrated. Simulated and measured results are in good agreement.

Compact and Sharp Skirts Microstrip Dual-Mode Dual-Band Bandpass Filter Using a Single Quadruple-Mode Resonator (QMR)

A new type of microstrip dual-mode dual-band bandpass filter (BPF) using a single quadruple-mode resonator (QMR) is proposed in this paper. The classical even-/odd-mode method is applied to analyze the characteristics of the proposed resonator, which shows that it has two pairs of symmetrical resonant modes. Owing to the inherent characteristic of a dual-mode resonator and source-load coupling, four transmission zeros can be produced and these four resonant modes can be divided in two groups, resulting in a dual-band BPF with two resonant modes in each passband. As examples, two dual-mode dual-band BPFs, Filter A with central frequencies (CFs) at 1.99/5.58 GHz and -3-dB fractional bandwidth (FBW) of 62.3%/19.7%, while Filter B with CFs at 1.64/5.26 GHz and -3-dB FBW of 32.9%/7.6%, are designed and fabricated. An aperture-backed compensation technique is employed in such two filters to enhance the coupling strength between the feeding lines and QMR. Furthermore, a meander coupled-line section is employed in the Filter A design, while a defected microstrip structure is introduced in Filter B design, so as to increase much more design freedoms for tuning filter performance. The fabricated two filters exhibit simple design procedures, low insertion losses, good return losses, sharp shirts, and compact sizes. Moreover, two BPFs do not need external input/output impedance transformation feeding lines.

Bandpass Filter With Tunable Bandwidth Using Quadruple-Mode Stub-Loaded Resonator

In this letter, a novel quadruple-mode resonator bandpass filter (BPF) with tunable bandwidth is proposed. By using two types of microwave varactors to tune the resonant frequencies and transmission zeros (TZs), the high-side edge of the passband and low-side edge of the passband can be separately varied. Therefore, the bandwidth could be tunable with reasonable adjust of the values of varactors. Theoretical expressions have been derived for the resonant frequencies and the TZs. The measured results of the BPF show that the fractional bandwidth can be tuned from 22% to 34% at a fixed centre frequency 2.0 GHz with a return loss better than dB. The tested results show good agreement with simulated results.

Microstrip-line millimetre-wave bandpass filter using interdigital coupled-line

An interdigital microstrip coupled-line bandpass filter is proposed for millimetre-wave application. A quadruple-mode microstrip-line resonator is designed to constitute the passband. The interdigital coupled-line sections are designed as the input/output network of the resonator. Meanwhile, sharp selectivity of the passband is achieved. As design examples, the in-band and out-of-band performances of a filter prototype using low-cost single-layer microstrip-lines has been designed and experimentally examined. The measured results show that the filter achieves a passband insertion loss of 1.07 dB at 40 GHz, the lower- and upper-stopband rejections are larger than 18 dB and 3 dB fractional bandwidth is 20%.

High Selectivity Broadband Bandpass Filter Using Stub-Loaded Quadruple-Mode Resonator

—In this paper, a compact and high selectivity broadband microstrip bandpass filter (BPF) using stub-loaded resonator is proposed. The basic block of the proposed filter is a quadruple-mode resonator consisting of a stepped-impedance resonator and three shunt open stubs. The proposed resonator can provide two even-mode, two odd-mode frequencies and two transmission zeros. The even-mode resonant frequencies can be flexibly controlled by the centre stub, while the odd-mode frequencies are fixed. The two other symmetrical stubs can both affect even- and odd- mode frequencies. The proposed filter exhibits high selectivity profiting from the two transmission zeros (TZs) near the passband created by two types of stubs. The measured –3 dB bandwidth is 1.0 GHz at the centre frequency of 2.5 GHz, and the S 21 exhibits a wide spurious free response up to 6 GHz. Measured results show good agreements with EM simulation results.

High rejection quadruple-mode broadband BPF with source-load coupling

A compact and high rejection broadband bandpass filter (BPF) with source-load coupling is proposed using the quadruple-mode stub-loaded resonator. Two identical folded open stubs near the centre plane can adjust high resonant frequencies fm3 and fm4 into the desired passband and create two transmission zeros to sharpen the upper skirt and suppress the resonant frequency fm5. Owing to the source-load coupling, two transmission zeros are created in the upper-stopband and near the lower cutoff frequency not only to deepen the upper-stopband, but also to sharpen the lower skirt. A filter with the fractional bandwidth 50% is simulated, fabricated and measured. Measured results agree well with EM simulations.

QUADRUPLE-MODE STUB-LOADED RESONATOR AND BROADBAND BPF

Novel compact microstrip quadruple-mode stub-loaded resonator and broadband bandpass fllter (BPF) are proposed in this letter. As a starting part of designing a quadruple-mode broadband BPF, the initial novel triple-mode open impedance-stepped stub loaded resonator characteristic is investigated to choose its proper dimensions. Based on these pre-determined dimensions of the triple- mode resonator, two identical short-circuited stubs are loaded against the impedance-stepped open stubs in the resonator to generate a tuned resonant mode and a transmission zero in lower stopband which leads to a high rejection skirt. A compact broadband BPF with the quadruple-mode resonator is simulated, fabricated and measured. The measured results agree well with the EM simulations.