Dual-mode Microstrip Bandpass Filter Research Articles

Highly selective microstrip bandpass filters using dual-mode patch resonator loaded with short via

In this paper, highly selective dual-mode microstrip bandpass filters (BPFs) are presented utilizing novel square patch resonator loaded with short via and periodic metallic vias array. Characteristics of the patch resonator are studied, and a new nondegenerate dual-mode patch resonator operating with the second and third higher-order modes is proposed. A two-pole BPF based on one dual-mode patch cavity is analyzed, and two transmission zeros (TZs) are produced. To realize higher-order filtering responses, four-pole BPFs with two cascaded dual-mode patch resonators are proposed, and different cascaded methods of two dual-mode patch resonators by a λg/4 microstrip connecting line (MCL) are analyzed and compared to maintain high selectivity and small size. For the demonstration, two four-pole filters with the center frequency at 3.3 GHz and five transmission zeros is designed, fabricated and measured.

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.

Novel Approach for Center Frequency and Bandwidth Tuning in Multimode Resonator Based Microstrip Dual-Mode Bandpass Filter

In this paper, a novel approach for both center frequency and bandwidth tuning in a dual mode bandpass filter is demonstrated. The proposed filter is configured from a half wavelength multimode resonator structure. The Ultra-wide bandpass response of the multimode resonator is extracted using an inter-digital feed structure which provides good input/output coupling. By deploying stepped admittance structure perturbation element into the symmetrical plane of the multimode resonator, the dual-mode response is achieved with three upper stopband transmission zeros (TZs). The coupling between two degenerative mode frequencies is controlled by the admittance ratio (Y) of the stepped admittance structure. Changing admittance ratio (Y) of stepped admittance structure, resulted in the change in even mode resonance frequency and location of three upper stopband transmission zeros while keeping odd mode frequency fixed. The proposed filter has a size of 14.0 x 30.0 mm2.

Fractally slotted patch resonator based compact dual-mode microstrip bandpass filter for Wireless LAN applications

A miniaturized dual-mode microstrip bandpass filter (BPF) based on fractally slotted patch resonator is presented in this paper. The proposed filter is centered at 2.4 GHz desirable for Wireless LAN applications. The dual-mode filter is realized using the fractally slotted structure on an octagonal patch resonator with perturbation. The design offers transmission zeros (TZs) at 2.19 GHz and 2.66 GHz on either side of the filter passband ensuring high selectivity. The locations of TZs from the center frequency can be adjusted by tuning the perturbation size. The filter is fabricated on a substrate with high permittivity and found to have a 3-dB fractional bandwidth (FBW) of 5% in the passband. Moreover, the measured minimum insertion loss is less than 0.91 dB and the return loss is greater than 23 dB in the passband. The prototype filter is fabricated and tested. Good agreement is accomplished between the experimental and simulation results. Furthermore, the footprint of the fabricated filter is about 0.416λg × 0.416λg where λg is the guided wavelength at 2.4 GHz.

Compact and high selectivity dual‐mode microstrip BPF with frequency‐dependent source–load coupling

In this letter, a dual-mode microstrip bandpass filter (BPF) with compact size and high selectivity is designed with a short-stub centred loaded resonator. Owing to the frequency-dependent source–load coupling and the intrinsic characteristics of the short-stub loaded resonator, three transmission zeros that are located near the passband edges and in the upper-stopband can be generated to improve the selectivity. The compact BPF with fractional bandwidth of 3.5% located at 2.4 GHz for WLAN application has been designed and fabricated, and good agreement between simulation and measurement verifies the validity of this design methodology.

Highly Selective Dual-Mode Microstrip Bandpass Filters Using Triangular Patch Resonators

In this paper, highly selective dual-mode microstrip bandpass filters are proposed using horizontal and vertical slots formed on the surface of a triangular patch. Slots are responsible for splitting and coupling of dual degenerate modes and also facilitate in controlling their resonant frequencies by varying the dimensions of the slots. Horizontal and vertical slots reroute the direction of the flow of current on the surface of the patch, which results in switching of transmission zeros. Two 2-pole and one 4-pole dual-mode filters are designed, simulated and fabricated. Two pole filters have transmission zeros on side of the passband and four pole filter have transmission zeros on both sides of the passband. The designed filters exhibit a fractional bandwidth of less than 7 % and there is a good agreement between simulated and measured results.

Investigation of New Microstrip Bandpass Filter Based on Patch Resonator with Geometrical Fractal Slot.

A compact dual-mode microstrip bandpass filter using geometrical slot is presented in this paper. The adopted geometrical slot is based on first iteration of Cantor square fractal curve. This filter has the benefits of possessing narrower and sharper frequency responses as compared to microstrip filters that use single mode resonators and traditional dual-mode square patch resonators. The filter has been modeled and demonstrated by Microwave Office EM simulator designed at a resonant frequency of 2 GHz using a substrate of εr = 10.8 and thickness of h = 1.27 mm. The output simulated results of the proposed filter exhibit 22 dB return loss, 0.1678 dB insertion loss and 12 MHz bandwidth in the passband region. In addition to the narrow band gained, miniaturization properties as well as weakened spurious frequency responses and blocked second harmonic frequency in out of band regions have been acquired. Filter parameters including insertion loss, return loss, bandwidth, coupling coefficient and external quality factor have been compared with different values of perturbation dimension (d). Also, a full comparative study of this filter as compared with traditional square patch filter has been considered.

Microstrip dual‐mode bandpass filter design using pie‐section truncated semi‐circle and quarter‐circle resonators

New dual-mode microstrip bandpass filters (BPFs) using pie-section truncated semi-circle and/or quarter-circle resonators are presented. The even-mode and odd-mode frequency responses of these two resonators are investigated. Compared to the four-parameter optimisation of the conventional stub-loaded dual-mode resonator, only three parameters need to be adjusted and optimised for the proposed resonators. Based on these two novel resonators, three BPF examples are designed, fabricated and tested. In addition, the technique of source-load cross coupling to improve performance of the filters is adopted. The good agreement between simulated and measured results validates the design concept.

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

A miniature fractal-based dual-mode dual-band microstrip bandpass filter design

In this paper, a fractal-based complementary split-ring resonator (CSRR) has been introduced as a defected ground structure (DGS) in the ground plane of a dual-mode microstrip bandpass filter to produce a new compact filter with dual-band response. The conventional double square ring resonator structure is modified such that its inner ring is made with a fractal shape instead of a square. Measured and simulation results show that the resulting filter offers a dual passband response; the higher passband is attributed to the dual-mode microstrip ring structure, whereas the lower passband is as a result of the embedded CSRR DGS structure. In addition, the results show that the position of the lower passband could be varied, to a certain extent, without affecting the position of the higher passband by applying higher fractal iteration levels to the inner split ring. These features, together with the compact size the proposed filter offers, make it suitable for use in a wide variety of dual-band communication applications. Measured results, carried out on filter prototypes, have been found in agreement with those theoretically predicted.

New dual-mode square patch bandpass filter using CSRR slot-type perturbation

A compact dual-mode microstrip bandpass filter using square-patch resonator and a new perturbation element is designed in this letter. This new slot-type element is composed by a complement split-ring resonator (CSRR) with two pairs of etching slots. The nature of coupling between the degenerate modes is investigated with respect to the perturbation size. By proper arranging the orientations of the CSRRs, new coupling characteristics can be obtained. The proposed dual mode bandpass filters are designed, and simulated. The simulation and measure results of proposed bandpass filter are reasonable.

Effects of narrow slits on frequency response of a microstrip square loop resonator and dual‐mode filter applications

AbstractIn this letter, the effect of narrow slits on resonance characteristics for a microstrip square loop resonator (SLR) with mitered bends is investigated and a new formula to calculate the resonance frequency of SLRs loaded inductively by means of slits is derived as a function of the number of slits.A novel dual‐mode SLR configuration performing a slow‐wave characteristic obtained by using narrow slits is proposed to use in design of microstrip dual‐mode bandpass filters. Also, a new perturbation technique based on the change of electrical lengths is presented for the excitation of two degenerated modes of these type resonators. Additional, two dual‐mode bandpass filters having linear phase and elliptical frequency characteristics have been designed, fabricated and tested to verify the proposed filter topology. Experimental results agree with simulated results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:143–146, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27237

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.

A Novel Dual-Mode Microstrip Bandpass Filter with a Pair of Equal Crossed Slots

A novel dua1-mode microstrip bandpass filter with two triangle corner cuts and a pair of equal crossed slots is proposed. The performance of the designed filter is studied in detail. The proposed filter structure uses a single patch without coupling gaps. The center frequency is about 2.11GHz. The 3dB relative bandwidth is 9.95%, and the minimum insertion loss in the passband is 0.12dB. Two transmission zeros can be implemented on both sides of the passband. The insertion loss is l0dB within 2.04-2.18GHz. The effect on the filter’s performance by changing filter parameters is studied. The results show that this new filter can provide a low loss and make miniaturization easy.

Compact and high selectivity dual-mode dual-band microstrip BPF with QWR and SLR

In this letter, a novel compact and high selectivity dual-mode dual-band microstrip bandpass filter (BPF) with quarter-wavelength resonator and stub-loaded resonator is proposed using extended feed lines.Either of the SIRs cannot only separately generate one passband but also mainly control the passband performance. Due to the extended feed lines, parasitic coupling and intrinsic characteristics of the resonators, multiple transmission zeros can be created to improve the selectivity. Meanwhile, the BPF can obtain compact size due to the folded resonators and feed lines. A dual-mode dual-band BPF with the fractional bandwidth 15.6 and 6.4% is designed and fabricated. The simulated and measured results show a better agreement and validate the proposed theory. The size is only 0.185λg × 0.130λg in which λgis the guided wavelength at the first passband center frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 2702:2705, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27211

Wide upper-stopband microstrip bandpass filter with dual-mode open loop stepped-impedance resonator and source-load coupling structure

In this article, a dual-mode microstrip bandpass filter (BPF) with compact size, sharp skirt, and wide upper-stopband performance is proposed using the short-stub-loaded open loop stepped-impedance resonator and source-load coupling structure. The advantageous features of the resonator are that the even-mode resonant frequencies can be controlled exclusively by the short stub, and two transmission zeros are created near the passband by the short stub and the folded arms. Meanwhile, two transmission zeros generated by the source-load coupling structure can be applied to suppress the first and second spurious harmonics. Finally, a microstrip BPF located at 2.4 GHz with a fractional bandwidth 4% is designed, fabricated, and measured. The upper stopband in experiment is extended up to 20 GHz with an insertion loss lower than −21.2 dB. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1618–1621, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26881

Compact and high selectivity dual-band dual-mode microstrip BPF with single stepped-impedance resonator

A novel dual-band dual-mode microstrip bandpass filter (BPF) with compact size and high selectivity performance is proposed using a single short-stub-loaded stepped-impedance resonator (SIR). Owing to the source–load coupling and the intrinsic characteristics of the SIR, five transmission zeros can be generated near the passband edges and in the upper-stopband to improve the selectivity. A dual-band filter located at 1.57 GHz (GPS application) and 5.35 GHz (WLAN application) has been designed, fabricated and measured. Good agreement between simulation and measurement verifies the validity of this design methodology.

Dual-mode dual-passband microstrip bandpass filter with a high selective performance

A dual-mode bandpass filter with a high selective performance for dual-band application is presented in this article.The filter is designed with square loop resonator with tree-shaped patches attached to the four inner corners of the loop, which equivalents to load capacitors in the inner of loop resonator. This loading can reduce the size of filter. The input/output feed lines located along a straight line. Such a feed arrangement is physically suitable for certain microwave networks. A demonstrated filter with the dual-band operating at 1.6 and 2.08 GHz was designed. Simulated and measured results indicate that a high selective dual-mode dual-band filter with wide harmonic responses has been achieved. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:666–669, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25784

Novel Broadband Bandpass Filters Using Y-Shaped Dual-Mode Microstrip Resonators

A Y-shaped dual-mode microstrip bandpass filter (BPF) with input-output cross-coupling is presented. The characteristic of the Y-shaped dual-mode resonator has been investigated. The resonance frequencies of the degenerate modes can be adjusted easily to satisfy the bandwidth of the BPF. A parallel-coupling feed structure with a cross coupling has been used to generate two transmission zeros at the lower and upper stopband, which can improve the out-of-band performance. A broadband dual-mode microstrip BPF has been designed, fabricated, and measured. The simulated and measured results are in agreement generally. Within the 3.1 to 5.4 GHz bandwidth, the measured insertion loss, return loss and group delay variation are below 0.5 dB, above 15 dB, and below 0.2 ns, respectively.

Novel dual mode microstrip bandpass-filter [Technical Committee

A novel four-pole, dual-mode bandpass filter is presented. It is based on microstrip meandered ring resonators, where dual-mode resonances are utilized through well-placed discontinuities in the symmetry plane of the ring structure. These filter types show very compact size, low insertion loss, and high stopband attenuation as well as steep filter slopes. The investigation was carried out within the student paper contest "Packaged X-Band Filter" at IMS 2008. Therefore, the passband is defined between 7.145--7.235 GHz, while the insertion loss is less than 5 dB and the return loss exceeds 15 dB. Between 8.4--8.5 GHz, the stopband attenuation should exceed 45 dB. This article presents the filter construction and simulation results. The integration into the given package as well as measurement results are presented.