Dual-mode Dual-band Bandpass Filter Research Articles

Dual‐mode dual‐band bandpass filter design utilising cylindrical TM‐mode cavities

This letter presents the design of a novel dual-mode dual-band bandpass filter that utilises the TM210 and TM020 modes of cylindrical cavity resonators for millimetre-wave operation when fed with standard WR-10 waveguide ports. In this manner, the two selected modes of the cylindrical cavity resonators are demonstrated as a single propagation path for fixed dual-passband responses without the need of cavity perturbations or tuning screws. The passbands are designated for centre frequencies at approximately 102.8 and 110.9 GHz and exhibit a four-pole Chebyshev characteristic in each of the passbands, which are separated by a transmission zero location. Simulated and measured results of the prototype are presented to verify the design.

Dual-mode resonator filter with improved feed-lines for dual-band applications

Abstract An improved feedline configuration for dual-mode resonator filter is investigated in this paper. Based on the introduced topology, a dual-mode dual-band bandpass filter with center frequencies of 1.8 and 2.4 GHz is optimally designed, fabricated and tested. The introduced dual-band bandpass filter has simple structure and enables high selectivity to be realized due to two pairs of transmission zeros located near to the lower and upper passband, respectively. Both measured and simulated performances are presented with good consistency.

Compact dual‐mode dual‐band HMSIW bandpass filters using source–load coupling with multiple transmission zeros

Compact dual-mode dual-band bandpass filters (BPFs) with multiple transmission zeros (TZs) using over-mode half-mode substrate integrated waveguide (HMSIW) resonators are presented. Each passband built by TE001 or TE201 has three TZs introduced by source–load coupling and low-/high-order mode cross-coupling between TE001 and TE201 to improve the frequency-selectivity. The equations that determined the TZs are built. Perturbation slots realise the independent-control of frequency ratio. Dual-mode dual-band BPFs are designed, fabricated and measured, and the simulated results agree with the measured results well.

Substrate-Integrated Waveguide Dual-Mode Dual-Band Bandpass Filters With Widely Controllable Bandwidth Ratios

A realization method, named the design parameters ratio technique, of substrate-integrated waveguide (SIW) dual-mode dual-band bandpass filters (DM-DBBPFs) with widely controllable bandwidth ratios is presented when TE101 and TE201 modes in substrate-integrated rectangular cavities are exploited to dominate the first and second passbands, respectively. Emphasis is placed on filters design to simultaneously realize the design parameters including the external quality factors $Q_{e}$ and coupling coefficients $M_{\mathrm{ ij}}$ required for both passbands by determining proper offset positions of the feeding ports and coupling windows, which can easily be fixed by ratios of synthesized $Q_{e}$ and $M_{\mathrm{ ij}}$ for the two bands, respectively. Consequently, the fractional bandwidths (FBWs) of the two passbands can be allocated flexibly over a wide range of ratios, typically with the FBW ratio of 0.2–1.5. Three SIW DM-DBBPFs including a third-order direct-coupled one operating at 12 and 16 GHz with the identical absolute bandwidths, a third-order cross-coupled one operating at 12 and 15 GHz with the same FBWs, and a fourth-order cross-coupled one operating at 12 and 17 GHz with the FBW ratio of 0.6 are designed and fabricated to demonstrate the method.

Design of a Compact Dual-Mode Dual-Band Bandpass Filter Using Stacked-Loop Resonators Structure

Design, fabrication and measurement of a high-selectivity dual-mode dual-band bandpass filter are presented in this paper. The resonance frequencies of the filter are 1.8[Formula: see text]GHz and 2.4[Formula: see text]GHz which are generated by a meander-loop resonator and a square-loop resonator. The two dual-mode single-band-loop resonators are stacked on each other and create a dual-band bandpass filter. Some advantages of our design are compact size, high selectivity, low loss and also no dependence of two bands, resonance frequencies on each other. The measurement results exhibit that the minimum insertion losses are 0.19[Formula: see text]dB for 1.8[Formula: see text]GHz and 0.32[Formula: see text]dB for 2.4[Formula: see text]GHz. Moreover return losses are better than 43.2[Formula: see text]dB and 40.6[Formula: see text]dB for 1.8[Formula: see text]GHz and 2.4[Formula: see text]GHz, respectively. The proposed filter has a size of [Formula: see text][Formula: see text]mm2. This microstrip filter is fabricated on RT/Duroid6010 substrate with dielectric constant 10.8 and thickness 1.27[Formula: see text]mm and its equivalent circuit is also offered. The measured results exhibit good agreement with the simulated ones.

Compact dual‐mode dual‐band bandpass filter with inside–outside–reversed dual‐ring topology

A compact dual-mode dual-band bandpass filter is proposed based on the inside–outside–reversed dual-ring topology. Different from the traditional design, the total size of the filter is limited by the second passband with shorter wavelength at higher frequency, instead of the first passband with longer wavelength at lower frequency. By loading four square patches in the inner ring, the degenerate modes of the inner ring move down and form the first passband, whereas the second passband is constructed by the outer ring. By utilising the coplanar-waveguide feeding at ground plane, a prototype of the dual-band filter with two operating frequencies at 0.92 and 1.47 GHz is designed and verified experimentally.

High‐selectivity dual‐mode dual‐band microstrip bandpass filter with multi‐transmission zeros

A dual-mode dual-band microstrip bandpass filter using the hybrid structure resonator derived from microstrip patch is proposed. Microstrip rectangular rings are used to excite the TE200 mode and TE002 mode of microstrip patch resonator, forming the high-frequency passband while it also works as a resonator which provides the low-frequency passband. The designed filter has 11 transmission zeros, resulting in good selectivity and good out-band rejection, extending the stopband, with a size of 0.45λ g × 0.41λ g. The measured results are in a good agreement with simulated results.

Planar dual-mode dual-band bandpass filter using a modified rectangular split-loop resonator loaded by an open-circuited stub

A compact planar dual-band bandpass filter using a new microstrip dual-mode resonator has been proposed in this article, which is based on a modified rectangular split-loop resonator loaded by an open-circuited stub. The implemented filter with two passbands has shown an excellent performance, including three transmission zeros disturbed nearby the two passband edges and between the passbands, by which a high selectivity is obtained for the proposed filter. Also, the measured results agree well with the simulated ones.

Compact dual‐mode dual‐band bandpass filter with wide stopband for WLAN applications

A compact dual-mode dual-band bandpass filter (BPF) for WLAN applications is presented. On the basis of a primary passband formed by a ring resonator, a second passband is introduced by taking advantage of its tightly coupled input and output structures. Therefore, a dual-band performance is achieved without increasing the overall circuit size. Shorting vias and spurlines are adopted separately to realise the dual-mode excitation of each passband. Finally, a compact dual-mode BPF centred at 2.4 and 5.2 GHz is designed and fabricated, along with four transmission zeros, leading to sharp skirts and a wide stopband. Experimental results reveal good agreement with simulation results.

Dual-mode dual-band microstrip bandpass filter with controllable center frequency

In this letter, a dual-mode dual-band microstrip bandpass filter design with center frequency control methodology is presented by using dual-mode meandered loop resonator. Center frequencies of the passbands can be controlled by changing the connection points of internally located square loop loading elements without changing the total surface area. These loading elements are also useful to obtain a compact configuration. In addition, while the first passband has two reflection zeros, the second passband has one reflection zero, as it is obtained from the harmonic of the first passband. Therefore, degenerate modes of the first passband can be excited by a perturbation element. Using patch or corner cut perturbation elements, elliptical and linear phase filtering characteristics can be obtained in the first passband, respectively. Two dual-mode microstrip bandpass filters having elliptical and linear phase filtering characteristics were designed, fabricated, and measured. Measured results are in a very good agreement with the simulated results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:639–642, 2015

Erratum: A compact dual-mode dual-band bandpass filter design with controllable first passband [IEICE Electronics Express Vol. 11 (2014) No. 23 pp. 20140991

Erratum: A compact dual-mode dual-band bandpass filter design with controllable first passband [IEICE Electronics Express Vol. 11 (2014) No. 23 pp. 20140991

A dual-mode dual-band bandpass filter using a tri-stubs loaded multimode resonator (TSLMR)

This paper presents a tri-stubs loaded multimode resonator (TSLMR) for designing dual-band bandpass filters. The TSLMR produces four spitting modes and the modal character is analyzed by using odd- and even-mode methods. A pair of even–odd modes is used to form the first passband, while another pair is used to produce the second passband. This resonator structure provides sufficient degrees of freedom to control the central frequencies and bandwidth of each passbands. Meanwhile, multi-transmission zeros are properly tuned for the rejections between the two passbands and in the upper stopband. A dual-band BPF operating at 1.57 and 3.5 GHz is designed and fabricated. Without a shorted structure and extra resonator, the measured filter shows good performance for both in band matching and outside rejections of the desired dual-passbands.

A compact dual-mode dual-band bandpass filter design with controllable first passband

A compact dual-mode dual-band bandpass filter design with controllable first passband

Design of dual-mode dual-band bandpass filters with controllable frequencies for multimode wireless communication applications

A flexible approach for designing dual-mode dual-band bandpass filters with controllable passband frequencies is presented. Two dual-mode dual-band bandpass filters are proposed for experimental verification. The first filter, whose two passbands are centered at 3.4 and 5.5 GHz with the corresponding fractional bandwidth of 19 and 13%, respectively, is suitable for the applications of worldwide interoperability for microwave access (WiMAX) and wireless local area network. The second filter, whose two passbands are centered at 4 and 7.4 GHz with the corresponding fractional bandwidth of 25 and 13%, respectively, is suitable for the downlink of C-band and X-band satellite communication systems. Both filters have been designed, fabricated, and measured. The measured results show good agreements with those of the simulation.

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.

Multilayer independently controllable dual‐band bandpass filter using dual‐mode slotted‐patch resonator

Presented is a novel multilayer dual-mode dual-band bandpass filter (BPF) using two identical microstrip cross-slotted patch resonators placed back-to-back. The lengths of the slots on the patch resonator are designed to be different, which can be used to control the two degenerate modes individually so as to build two passbands of the proposed BPF. Two separated coupling paths for the two modes can be realised by the etched slits on the common ground plane of the two microstrip resonators. As a result, the coupling coefficients between the two resonators in each passband can be controlled independently. Furthermore, a new source-load coupling scheme is incorporated in this design to enhance the stopband rejection and then improve the band-to-band isolation significantly.

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.

A novel compact configuration for dual-mode microstrip resonators and dual-band bandpass filter applications

In this article, a novel compact dual-mode resonator formed by a square loop having folded arms and mitered bends is proposed.Degenerate modes can be excited by shifting the gaps between the folds. Thus, the center frequency can be arranged at a fixed value because the total electrical length of the proposed configuration is not changed. A novel compact dual-mode dual-band bandpass filter is also designed by locating the one resonator within the other. Additionally, to suppress the harmonic of the first passband, open-circuited stubs are connected to the end of the feedlines. Two dual-mode dual-band bandpass filters with the elliptical and linear phase filtering characteristics for both passbands have been designed, fabricated, and tested. Calculated, simulated, and measured results are in a good agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:775–779, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27444

Dual-Mode Dual-Band Bandpass Filters With Adjustable Frequency RatioUsing an Annular Ring Resonator

A single annular ring resonator is proposed to design a dual-mode dual-band bandpass filter (BPF) with adjustable frequency ratio of the two passbands. The two passbands are formed by the first two pairs of degenerate modes of an annular ring resonator. The change of the inner concentric circular radius leads to the variation of surface current distributions of the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> resonant modes accordingly. As a result, the frequency ratio between 1.65 and 2.00 can be achieved when it changes between a circular patch and a ring resonator. The resonator is inductively coupled to the input and output ports by a pair of high impedance lines. To verify the design principle, two filters with different frequency ratios of the two passbands, 1.75 and 1.90, are designed, fabricated and measured. The experimental results agree well with the predicted ones.

Design and analysis of a compact dual-mode dual-band microstrip bandpass filter

Design and fabrication of compact dual-mode dual-band microstrip bandpass filters with a novel feed scheme is presented. The proposed filters have two square loop resonators for two passbands, and each resonator is fed by the feedlines located at the upper corners of the resonators. By using the perturbation elements such as patches or corner-cuts, two degenerate modes of each passband can be easily excited, so mode frequencies and transmission zeros of the passbands can be controlled independently. Also, the proposed feed scheme provides the harmonic suppression for the first passband. In addition, theoretical results have been obtained by using an equivalent circuit model, and a coupling scheme is also presented. The designed filters have an electrical length of for the quarter wavelength resonator, where is the guided wavelength at 1.8 GHz. Two bandpass filters having elliptical and linear phase filtering characteristics in each passband have been designed, fabricated, and tested. Measured results are in an excellent agreement with simulated and calculated ones. In all frequency responses, return losses are better than 15 dB and insertion losses are at acceptable values for both passbands.