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This paper presents a novel compact wideband quadruple-mode bandpass filter (BPF) with four resonant modes and five transmission zeros (TZs). Two T-shaped stepped impedance stub loaded resonators are coupled in parallel to the input and output feed lines to form the entire BPF. To provide a wideband and outstanding rejection in upper stopband, the two TZs are introduced by the stepped impedance stub as well as the designed coupling capacitor, and the two inherent TZs produced by the coupling between the resonators and feed lines are used and carefully tuned. The proposed BPF is fabricated in 65 nm CMOS technology with a core area of 0.072 mm2 (7.1×10-3 λ02). The measurement results show that the 3-dB bandwidth is 24.2 GHz at the center frequency of 94 GHz as well as the minimum insertion loss is 4.6 dB. Meanwhile, the stopband extends to 170 GHz with a stopband rejection above 25 dB.

Bandpass filters for millimeter-wave band applications are typically designed using resonators. However, the design of a multilayer coplanar waveguide (CPW) monolithic microwave integrated circuit (MMIC) bandpass filter for 5G millimeter-wave band, n257 with operating frequencies from 26.5 to 29.5 GHz is still not available. Therefore, in this work, a compact bandpass filter for 5G millimeter-wave application was designed with multilayer CPW MMIC bandpass filter based on a meander resonator. The meander resonator of the bandpass filter was designed using low-loss multilayer CPW lines. In designing the bandpass filter, the resonator length and perturbation was utilized to optimize the resonance and bandwidth, and meander resonator was used to miniaturize the bandpass filter. As result, a compact bandpass filter with size of 0.75×0.75 mm2 for 5G millimeter-wave band n257 was achieved. It has bandwidth of 3 GHz, an insertion loss of -2.87 dB and a return loss of -11.1 dB at frequency 28 GHz. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a high‐selective crossover with a third‐order filtering characteristic, high passband isolation, and multiple controllable transmission zeros based on a coupled topology using single‐ and dual‐mode resonators. By virtue of the odd‐ and even‐mode feature of the stub‐loaded dual‐mode ring resonator, not only can the two resonant modes for different passbands be relatively independently controlled, but also better isolation can be achieved. With a single‐mode resonator and stub‐loaded dual‐mode resonant coupling topology, the resultant crossover can perform third‐order filtering performance in two distinct passbands/channels and generate several transmission zeros outside the desired bands to improve the isolation between the passbands. Experimental results demonstrate that, compared with conventional works, the filtering order of the proposed crossover is promoted and its passband isolation can be significantly improved by about 8 dB. The proposed work may facilitate its widespread applications in high‐performance multichannel integrated microwave systems for avoiding interference between multiple intersecting signal paths. [ABSTRACT FROM AUTHOR]

In this letter, a compact circularly polarized (CP) microstrip patch filtenna designed by reusing dual‐mode substrate integrated waveguide (SIW) cavity is proposed. The dual‐mode SIW cavity, operating at its TE120 and TE210 modes, can be used not only as the first stage resonator of the filtering network but also feeds the four microstrip patches working at their TM10 and TM01 modes. A pair of asymmetric perturbed posts is inserted in the SIW cavity to perturb the electric field distributions of TE120 and TE210 modes so as to achieve one axial ratio (AR) minima. The other AR minima is realized by sequentially exciting the four orthogonal microstrip patches via the four rectangular slots that are etched on the top surface of the SIW cavity. In addition, four metal posts penetrated the SIW cavity is employed to improve the impedance matching. For verification, a CP filtenna prototype centered at 5.13 GHz is designed, manufactured, and tested. The measured results agree well with the simulated ones, demonstrating a fractional impedance bandwidth of 6.9% (4.95–5.3 GHz), a 3 dB AR bandwidth of 4.2% (5–5.21 GHz), and a maximum boresight realized gain of 8.4 dBic. [ABSTRACT FROM AUTHOR]

A novel dual-band bandpass filter (DB-BPF) based on SIW dual-mode resonant cavity is proposed in this study. This resonant cavity works in the degenerate mode TE102 mode and TE201 mode. The two modes of operation are coupled by opening a window between the resonant cavities, and the passband frequency of the DB-BPF is adjusted by controlling two degenerate modes. This filter works at 9 GHz and 9.5 GHz and has a 3-dB fractional bandwidth of 2.2% and 3.5% GHz, respectively, and has three transmission zeros (TZs) which improve out-of-band rejection and isolation between high-passband and low-passband. The return loss in the high-passband and low-passband is below 13 dB; the insertion loss of the high-passband and low-passband is 2.32 dB and 3.16 dB, respectively. The measured results agree well with the simulation results, which proves the feasibility of the design method. [ABSTRACT FROM AUTHOR]

In this paper, we study meandered topologies of a dual-mode loop resonator for microwave multiplexer applications. Compact channel filter structures that characterize controllable transmission zeros locating simultaneously at the lower stopband or upper stopband are, for the first time, investigated for such a kind of resonators and based on this, a microstrip triplexer is proposed. The studied triplexer uses one of the filter structures to realize the middle channel, and the rest structure to realize the upper and lower channels. The center frequencies of the three channels are 1.8 GHz, 2.0 GHz and 2.2 GHz, and the 3-dB fractional bandwidths are 3.6%, 3.6% and 4.1%, respectively. The developed triplexer features high channel-isolations of over 40 dB as a result of the controllable transmission zeros of the channel filters. [ABSTRACT FROM AUTHOR]

In this paper, a dual-mode loop resonator based circuit topology is studied for microwave diplexer applications. Several diplexers, with dense and sparse channel separations, are further discussed based on the introduced topology, featuring capable of controlling transmission zeros flexibly. Hence microwave diplexers with high selectivity and good channel isolation can be realized by placing transmission zeros of the channel filters at the desired channels. With the use of the proposed topology, the achieved center frequency ratio between two channels can be from 1.03 to 1.35 with good isolations, high selectivity and compact size. The demonstration diplexers are realized on PCB processes, but can be implemented with other media including MMIC. Experimental validations on the developed demonstrator are presented in the paper, and measured responses match well the full-wave electromagnetic simulated results. The developed UMTS diplexer demonstrator achieves the measured minimum passband insertion losses of 2.55 and 2.7 dB with return losses better than 15 dB and channel isolations over 40 dB at the two channels.

A new compact bandpass filter with transmission zero control based on the suspended microstrip dual mode technology is proposed. A square-shaped resonator on Rogers/Duroid 5880 substrate is placed in the middle of a metallic cavity. A new configuration of four posts grounded from the top and bottom of the cavity are lied in the middle of each side of the square resonator to improve the spurious window. A 2nd order bandpass generalized Chebyshev filter is designed and simulated to operate at a resonant frequency of 4.8GHz with a bandwidth of 100MHz, which are suitable for 5G applications. The internal coupling was achieved by itching the resonator at 45° between two degenerated mode. The results show a two TZs located at the upper and lower side with a good controllability. The spurious window was about 2 and the filter offers a 50% size reduction compared to the traditional suspended microstrip. [ABSTRACT FROM AUTHOR]

In this article, a new compact, wide bandwidth dual‐band bandpass filter (DB‐BPF) with four transmission zeros (TZs) is proposed. A dual‐path configuration is realized by cascading different dual‐mode resonators. The novel dual‐mode resonators are based on stepped impedance resonators (SIRs) that generate the TZs owing to their intrinsic characteristics. The proposed DB‐BPF can fulfill simultaneous independent control of the external and internal‐resonator coupling. The design procedure based on the cascaded dual‐mode resonators and frequency transformation is also introduced. The surface current distributions are simulated to verify the performance of the proposed filter. The measured results show 2.14/4.33 GHz DB‐BPF with 3‐dB fractional bandwidth (FBW) of 0.27/0.15, respectively, which is suitable for WLAN applications. The return and insertion losses of the passband are better than 15/15‐dB and less than 0.8/1.3‐dB, respectively. The overall physical size of the fabricated DB‐BPF is 20.4 mm × 20.4 mm, equivalent to 0.23λg × 0.23λg, where λg is the guided wavelength at 2.14 GHz. The simulation results are in good agreement with the measurement results. [ABSTRACT FROM AUTHOR]

In this paper, a dual-mode loop resonator based circuit topology is studied for microwave diplexer applications. Several diplexers, with dense and sparse channel separations, are further discussed based on the introduced topology, featuring capable of controlling transmission zeros flexibly. Hence microwave diplexers with high selectivity and good channel isolation can be realized by placing transmission zeros of the channel filters at the desired channels. With the use of the proposed topology, the achieved center frequency ratio between two channels can be from 1.03 to 1.35 with good isolations, high selectivity and compact size. The demonstration diplexers are realized on PCB processes, but can be implemented with other media including MMIC. Experimental validations on the developed demonstrator are presented in the paper, and measured responses match well the full-wave electromagnetic simulated results. The developed UMTS diplexer demonstrator achieves the measured minimum passband insertion losses of 2.55 and 2.7 dB with return losses better than 15 dB and channel isolations over 40 dB at the two channels. [ABSTRACT FROM AUTHOR]

A design of a microstrip quad-band BPF with flexibly controlled bandwidth is presented in this paper. Two dual-mode short-circuited SLRs with a common via-hole are proposed, which are utilized to obtain the first and second passband, while the third passband is generated by implementing the second-order half-wavelength coupled-line resonator. Another dual-mode open-circuited SLR can be operated at the fourth passband. The proposed quad-band BPF is centered at 1.80/2.45/3.50/4.90 GHz for DCS/WLAN/WiMAX and 5G applications. By appropriately choosing the lengths of the four sets of resonators, all passbands can be fully varied independently with minimal effect on other passbands. Moreover, the bandwidth of each passband can be flexibly controlled by tuning the coupling parameters. The dimension of the fabricated proposed filter is about 0.12 × 0.20 λg, indicating the compactness of the design, whereas the measurements are in good agreement with the simulated results. The measured S11 are at least 12 dB in the four passbands. The passbands S21 are approximately 0.65, 1.42, 0.78, and 1.20 dB, which exhibit low insertion loss at the passband frequency of the first, second, third, and fourth passband, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a horn antenna with a 5th‐order dual‐mode ellipsoid resonator filtering network, fabricated by stereo lithography apparatus 3‐D printing technic. The filtering part employs two dimpled ellipsoid dual‐mode resonators, operating at the fundamental TM101 mode. Compared to the filters employing cylindrical resonators with tuning posts, the proposed filtering network is with lower loss (due to the high Qu resonator) and the performance is less sensitive to the fabrication errors. The antenna was demonstrated at Ku band (12–18 GHz), with a measured RL >10 dB across the passband of 14.6–15.4 GHz. The measured gain of the antenna is 11.4 dBi at 15 GHz and maximum in‐band gain variation is 0.4 dB. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, a novel triple wideband bandstop filter design is proposed with two adjacent microstrip square loop resonators (MSLR) having different edge lengths. Degenerate modes of the square loop resonators are induced by using direct coupling mechanism. Perturbation and loading elements are located on resonators and used to control reflection zeros between the second and third bands. Even odd mode analysis of a single direct coupled dualmode resonator is also extracted to elucidate the filter topology. The proposed resonator structure is designed by using a full-wave EM simulator and three different filter responses are obtained from the designed resonator structure. One of the filters is fabricated and, it is observed that measured results are compatible with simulated results. [ABSTRACT FROM AUTHOR]

In this paper, a reconfigurable dual-band bandpass filter, using memristive switches, is proposed. The applied memristor is non-volatile and has low-power consumption, which could be potentially used as an RF switch. The dual-band bandpass filter is based on the dual-mode resonator with a memristor. The odd-mode and even-mode method is utilized to analyse the proposed reconfigurable filter. By loading a memristor to the optimum position of the resonator, the proposed dual-band bandpass filter's responses can be switched. The memristor is equivalent to a low-impedance resistor in ON state and a high-impedance capacitor in OFF state. The frequency responses of the proposed reconfigurable dual-band bandpass filter can be tuned by transforming the state of two memristors. The alternative test method is used in this paper, and measured results are consistent with simulated results. [ABSTRACT FROM AUTHOR]

In this article, a novel dual-mode monoblock dielectric resonator (MDR) for compact monoblock dielectric bandpass filters is presented and put into practical use for the first time. In the dual-mode resonator, two dissimilar TEM modes are generated by forming two perpendicular metalized blind holes in a silver-coated cuboid-shapes dielectric block. The resonator can maximize the space utilization with up to 50% volume reduction while maintaining a wide spurious-free frequency band. The coupling of the two modes in such a resonator can be effectively controlled by one or more partial-height metalized posts. A convenient input/output (I/O) coupling scheme for surface-mount applications is introduced, and versatile coupling arrangements for realizing various filter characteristics are presented. To demonstrate the proposed filter miniaturization technique, a six-pole inline bandpass filter with one pure imaginary transmission zero (TZ) in a 3.5-GHz band is electromagnetic (EM) designed, and a ten-pole symmetric bandpass filter with two pure imaginary TZs in a 2.6-GHz band of fifth-generation (5G) new radio (NR) frequency band is designed, prototyped, and tuned. Experimental results show that the proposed dual-mode MDR filter can obtain an acceptable RF performance for 5G applications with a significant volume reduction compared to existing single-mode solutions. [ABSTRACT FROM AUTHOR]

This paper presents the design of frequency-tunable dual-band, tri-band and quad-band bandpass filters (BPFs). The proposed three BPFs can be independently tuned and individually switched by varying the capacitances of the varactors. In the designed tunable dual-band BPF (TD-BPF), common input/output feed lines are utilized for two tunable dual-mode resonators (TDRs). Further, three TDRs and four TDRs are employed to achieve tunable tri-band BPF (TT-BPF) and tunable quad-band BPF (TQ-BPF), respectively. Then, the TD-BPF and the TT-BPF are fabricated and measured to verify individual tunability and independent switchability. For the TD-BPF, the measurement results show that the center frequency (CF) of the first passband varies from 1.37 to 1.62 GHz, and the CF of the second passband varies from 2.3 to 2.64 GHz. In the measured TT-BPF, the tuning ranges of CFs of three passbands are 1.3–1.5 GHz, 2.36–2.6 GHz, and 3–3.54 GHz, respectively. [ABSTRACT FROM AUTHOR]

This work presents a series of independent bandpass filters (BPFs) based on dual-mode resonators (DMRs) with short stub-loaded. BPFs conform to the 802.11n protocol and include three passbands with center frequencies and bandwidths of 2.46 GHz, 3.55 GHz and 5.22 GHz, 130 MHz, 130 MHz and 470 MHz. Insertion loss and reflection loss are 1.5 dB, 1.6 dB and 1.3 dB, 18 dB, 20 dB, 30 dB. The filters are useful in the WLAN/WIMAX applications with compact size. According to the current distributions along the resonator, the feed-lines with high design flexibility arms were introduced in order to supply the needed external coupling for the dual-/tri passbands simultaneously, and achieve good impedance matching in each passband. Finally, by the version 15 of High Frequency Structure Simulator (HFSS), three BPFs with single, dual and triple passbands were designed on the Rogers 5880 substrate with the relative dielectric constant ɛr = 2.2, substrate loss tanδ = 0.002, and the thickness h = 0.508 mm. The BPFs are measured by Agilent 85058E Vector Network Analyzer (VNA). The measured results have good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

Two novel substrate integrated waveguide (SIW) high-isolation dual-mode diplexers based on electromagnetic perturbation technology have been presented in this paper. The capacitive perturbation and inductive perturbation have been introduced in the presented dual-mode diplexers. Furthermore, this perturbation can produce two transmission zeros in the real frequency axis, and those transmission zeros in the real frequency axis can improve the frequency selectivity of each channel of the diplexer and the isolation between two channels. Two different SIW dual-mode diplexers have been designed, fabricated, and measured. The measured insertion losses at each center frequency are 2.2 and 2.4 dB for the diplexer 1, 1.8, and 1.5 dB for the diplexer 2, with the fractional bandwidths of 1.95% and 2.08% for the diplexer 1 and 1.94% and 2.05% for the diplexer 2. The isolation is greater than 45 dB. Reasonable agreement between the simulated and measured results is achieved for the proposed dual-mode SIW diplexers.

A design of a microstrip quad-band BPF with flexibly controlled bandwidth is presented in this paper. Two dual-mode short-circuited SLRs with a common via-hole are proposed, which are utilized to obtain the first and second passband, while the third passband is generated by implementing the second-order half-wavelength coupled-line resonator. Another dual-mode open-circuited SLR can be operated at the fourth passband. The proposed quad-band BPF is centered at 1.80/2.45/3.50/4.90 GHz for DCS/WLAN/WiMAX and 5G applications. By appropriately choosing the lengths of the four sets of resonators, all passbands can be fully varied independently with minimal effect on other passbands. Moreover, the bandwidth of each passband can be flexibly controlled by tuning the coupling parameters. The dimension of the fabricated proposed filter is about 0.12 × 0.20 λg, indicating the compactness of the design, whereas the measurements are in good agreement with the simulated results. The measured S11 are at least 12 dB in the four passbands. The passbands S21 are approximately 0.65, 1.42, 0.78, and 1.20 dB, which exhibit low insertion loss at the passband frequency of the first, second, third, and fourth passband, respectively.

This article presents a novel balanced diplexer based on substrate integrated waveguide (SIW) dual-mode resonator. The six-port model has been introduced in this article to achieve the conversion of S-parameters between balanced and unbalanced devices. The SIW dual-mode resonator with common-mode (CM) rejection capability is able to restrain CM signal in the passband of the diplexer. Moreover, the CM rejection performance is improved by etching the slotline on the surface of SIW without changing the transmission of the differential-mode (DM) signal. A diplexer with lower and higher channels centered at 8.8 and 9.4 GHz, with a 3-dB FBW of 4% and 4.8%, respectively, is designed and fabricated to verify the proposed concept. The measured results show that the CM rejection is greater than 42/45 dB and the DM isolation between the lower and higher channels is greater than 35 dB in passband, which shows good agreements with simulations. [ABSTRACT FROM AUTHOR]

This Letter presents a miniaturised wide tuning-range four-way filtering power divider (FPD). It is mainly developed by integrating a co-shared varactor-loaded quasi-lumped-element dual-mode resonator and an isolation resistor, achieving a wide tuning power division ratio (PDR) and centre frequency (CF) simultaneously. The presented tunable four-way FPD stands out from those in the literature, by both its improved performance (wider tuning range for PDR and CF with nice isolation and matching) and ultra-compact design layout. To validate the design concept, a reconfigurable prototype is designed, fabricated, and tested. Measured results will coincide with the simulated ones. [ABSTRACT FROM AUTHOR]

A novel third‐order tunable cross‐coupled trisection bandpass filter (BPF) based on dual‐mode resonators (DMRs) is presented in this letter. Electric and magnetic dominant coupling path can be constructed by using two coupled DMRs to meet the requirement of cross‐coupled tunable bandpass filter with constant bandwidth. Three resonating modes of the two DMRs are used to build the cross‐coupled trisection tunable bandpass filter topology. The coupling structure is analyzed and the coupling coefficients are calculated. The tunable BPF is designed, and a transmission zero (Tz) due to the cross‐coupled trisection topology is generated, so that frequency selectivity is enhanced. The prototype is fabricated and measured. The measured results show that the fabricated circuit realizes a tunable central frequency range from 1.64 to 2.16 GHz, maintaining a −3 dB bandwidth of 119.5 ± 3.5 MHz, and a Tz is generated at the lower side of the passband. [ABSTRACT FROM AUTHOR]

A high-isolation diplexer based on a dual-mode substrate integrated waveguide (SIW) resonator is proposed in this paper. Based on the theory of the dual-mode resonator, the miniaturized diplexers are designed by using the SIW dual-mode resonators. The superior isolation of the diplexers is obtained because the two operating modes of the dual-mode SIW resonators are not directly coupled and there is no interference with each other. In order to further improve the isolation of the circuit, the number of the order of the diplexer is added. Equivalent circuits are given to analyze and design the dual-mode high-isolation diplexers. Detailed analyses are given according to the equivalent circuits. The dual-mode third-order and fourth-order diplexers are designed and fabricated. The measured results agree well with the simulated ones. The total sizes of the fabricated third-order and fourth-order diplexers are 1.78 λ g × 2.64 λ g and 1.79 λ g × 3.63 λ g, respectively. [ABSTRACT FROM AUTHOR]

Circularly polarized slot antennas based on dual-mode elliptic substrate integrated waveguide (SIW) cavities are proposed in this letter. Current distribution on the dual-mode cavity is analyzed first to facilitate the layout design. The antennas are divided into three categories. For the first one, three unbalanced slots are etched on the upper surface of the cavity with a central rectangular slot placed perpendicularly to the arc-shaped slots on the two sides of the long axis. For the other two antennas, two pairs of symmetric arc-shaped slots are etched on the upper surface of the cavity. One of them has an additional shorting-pin in the center. Circular polarization is achieved by simultaneously exciting two quasi-TM110 cavity modes and combining them in the 5–6 GHz frequency range. The working principle of the dual-mode antennas is theoretically illustrated in detail and experimentally verified. The proposed antennas offer attractive features, including novel working principle, simple structure, low loss, low profile, low cost, and good gain, appearing as good candidates for indoor communication. [ABSTRACT FROM AUTHOR]

This article presents a novel folded configuration of dual-band filter employing TE $_{11m}$ dual-mode elliptical cavity resonators. The proposed side-coupled configuration leads to a significant reduction of filter footprint compared with previously reported in-line dual-band filter structures. Such configuration also facilitates cross couplings to realize advanced quasi-elliptic filter functions. The structure employs irises for both sequential and cross couplings. The limitations of bandwidth realization and spurious-free window are analyzed in detail, and new coupling structures are proposed to improve the overall in-band and out-of-band responses. All the proposed dual-band designs have low insertion loss and allow for independent control of each frequency and coupling parameter. To demonstrate the concept, two 8-pole C-band elliptical cavity dual-band filters are designed, manufactured, measured, and compared. To the best of the authors’ knowledge, this is the first reported folded dual-band filter configuration based on metallic waveguide cavities. [ABSTRACT FROM AUTHOR]

This paper proposes a compact bandpass filter using a folded ring resonator, which occupies an area, one-quarter the size of a conventional ring resonator. For the filter design, circuit modeling is used to derive the coupling coefficients between the even- and odd-mode resonances of the proposed resonator with the perturbation stub. The validity of the proposed filter is demonstrated by designing and fabricating a two-pole bandpass filter with a 100 MHz bandwidth at the central frequency of 2.45 GHz [ABSTRACT FROM AUTHOR]

A compact high-isolation power divider with bandpass response and high-frequency selectivity is presented in this letter. Two dual-mode resonators are used to realize filtering response. The circuit size of the proposed power divider can be reduced by using dual-mode capacitance loaded square meander loop resonators. Due to capacitive load, the resonator can exhibit slow-wave characteristics, which can be utilized to suppress harmonics and reduce size. The simulated and measured results show reasonable agreement. [ABSTRACT FROM AUTHOR]

In this article, a compact bandstop filter (BSF) with desirable four attenuation narrow bands is developed for multiple wireless network systems. The developed filter composes of two microstrip circuits. In the first microstrip circuit, stepped-impedance and two open-circuit stubs in defected microstrip structure (DMS) are analyzed to generate the first and the second rejection bands. The third and the fourth stopbands are realized using a second microstrip circuit consist of two dual-mode resonators. This circuit are capacitively coupled to the DMS-circuit. The filter attitude is very well explained using a coupling mechanism diagram. To demonstrate the developed concept, dual and quad-bandstop filters are designed, fabricated, and measured to supress the frequencies of (2.4 GHz and 5 GHz WLAN) and (1.56 GHz GPS, 2.4 GHz WLAN, 3.5 GHz WiMax, and 5.25 GHz WLAN) respectively. The measured results agree with the predicted ones closely. The measured responses improved that the quad-BSF can apply 10 dB attenuation bandwidths of 81 MHz, 73 MHz, 60 MHz, and 129 MHz centred at 1.56 GHz, 2.4 GHz, 3.5 GHz, and 5.25 GHz respectively. The designed filter has overall circuit area of 125 mm2 excluding the feeding ports. [ABSTRACT FROM AUTHOR]

This letter presents a substrate-integrated-waveguide-based compact, dual-mode self-diplexing antenna. A single square cavity with a rectangular ring slot is used for both dual-mode excitation and radiation. A prototype diplexing antenna is fabricated that radiates linear, orthogonal polarization at 9.5 and 10.5 GHz. The measured peak gains at the two frequencies are 5.75 and 5.95 dBi, respectively. Intermodal coupling between the modes provides two transmission zeros, which are utilized to achieve port isolation better than 29 dB. The proposed technique can be used for closely spaced radiating frequencies. As no external filter is used, the structure is compact. Furthermore, because of the slot loading effect, the antenna is smaller than a recently published antenna claimed as the most compact antenna. Its working principle is discussed in detail. Finally, design guidelines are suggested. [ABSTRACT FROM AUTHOR]

This paper introduces a novel microwave planar filter design using triple–mode resonator. In order to achieve the filter size reduction we use the multilayer technology. The structure consists of two dielectric layers separated by a common ground plane. The triple – mode resonator consists of two dualmode resonators which are placed on different sides of dielectric layers. Electrical connection between the two resonators is realized by using a via-hole. We use the dual-mode resonator with the short circuited central stub. The filter is designed for the center frequency of 1 GHz. In order to reduce the simulation time for the filter design, we propose a new circuit model, because the circuitlevel simulations are significantly faster than three-dimensional electromagnetic (3D EM) simulations. The 3D filter structure is decomposed into domains and each of them is modeled by a microwave network. The results of the 3D EM simulation and circuit-level simulation are in good agreement. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR32005]

In this paper, a novel microwave higher-order filter design is presented using dual-mode resonators. The filter is realized in multilayer technology in order to reduce the footprint area. The structure consists of two dielectric layers separated by a common ground plane. The filter is realized with two resonators which are printed on different sides of dielectric layers. The conductive coupling between the resonators is realized with a via. The coupling between the resonators is investigated as a function of the via position. The proposed filter design achieves a size reduction of 50% as compared to classical microstrip design.

In this paper, we propose novel microstrip-ridge gap waveguide (MS-RGW) millimeter-wave bandpass filters based on a dual-mode resonator. The resonator represents a rectangular patch grounded by a set of vias, whose pair of fundamental degenerate modes are separated in the spectrum using the via position perturbation. MS-RGW feeding lines are realized as periodically grounded microstrip lines inserted into a perfect magnetic conductor (PMC) structure, which are fed via the 2.92-mm connector through the specifically designed transition. A detailed analysis of the filters is provided together with the analysis of their building blocks—mushroom-based PMC surface, MS-RGW with periodically grounded microstrip line, and dual-mode resonator. The proposed filters are fabricated using standard PCB technology and the measured results show that the filters exhibit low losses, good in-band and out-of-band characteristics, and good selectivity. As such, the proposed filters represent excellent candidates for millimeter-wave filtering applications since they reconcile the requirements for high performance, low loss, and low cost. [ABSTRACT FROM AUTHOR]

Abstract A novel memristor-based multilayer dual-mode resonator is presented, which is suitable for the design of reconfigurable multi-band filters. The memristor is used as an RF/microwave switch. A dual-band bandpass filter is realized with the proposed memristor-based dual-mode resonators. The corresponding memristor setup circuitry is optimized in order to minimize the circuitry influence on the desired filter frequency response. [ABSTRACT FROM AUTHOR]

A bandpass-filtering-response power divider with good isolation is presented in this paper. The short-circuited-loaded resonators are employed to construct the presented compact power divider. The presented divider can be viewed as an integration of a second-order dual-mode bandpass filter and the quasi-Wilkinson power divider. The simulated and measured results of the proposed power divider demonstrate good performance, such as about 30-dB high isolation among the output ports, wide upper stopband, excellent amplitude and phase balancing, and reasonable bandpass-filtering response. [ABSTRACT FROM AUTHOR]

This paper explores a dual-mode resonator that uses laterally coupled alternating thickness (LCAT) modes, and a dual-passband filter for WiFi 2.4G and n77 bands is constructed. The resonator's frequency can be adjusted by the electrode thickness, period and piezoelectric film thickness, and their effects on the quality factor (Q) values and effective electromechanical coupling coefficient (k 2 eff) were analyzed. In addition, the impact of Sc-doped concentration on resonators' performance was investigated, and the AlSc 0.35 N-based resonators exhibited both high Q and k 2 eff values. Furthermore, two resonant modes were effectively excited by setting two working regions. Adding an acoustic blocking groove reduces mutual acoustic energy leakage, increasing Q values for target modes and suppressing spurious signals. The dual-mode resonator' structure were further optimized to ensure that both modes have similar high performance. Ultimately, this work constructs a dual passband filter with center frequencies of 2.49 and 3.54 GHz with 75 and 132 MHz bandwidths respectively, and achieves over 60 dB out-of-band rejection. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel microwave microfluidic sensor with dual-sensing capability. The sensor is based on a dual-mode resonator that consists of a folded microstrip line loaded with interdigital lines and a stub at the plane of symmetry. Due to the specific configuration, the resonator exhibits two entirely independent resonant modes, which allows simultaneous sensing of two fluids using a resonance shift method. The sensor is designed in a multilayer configuration with the proposed resonator and two separated microfluidic channels--one intertwined with the interdigital lines and the other positioned below the stub. The circuit has been fabricated using low-temperature co-fired ceramics technology and its performance was verified through the measurement of its responses for different fluids in the microfluidic channels. The results confirm the dual-sensing capability with zero mutual influence as well as good overall performance. Besides an excellent potential for dual-sensing applications, the proposed sensor is a good candidate for application in mixing fluids and cell counting. [ABSTRACT FROM AUTHOR]

In this paper, a novel microstrip diplexer with tunable bandwidths and switchable channels is presented by using dual-mode square loop resonators (DMSLRs). Two resonators at different electrical lengths are coupled to input and output ports with lumped capacitors, and the isolation between the output ports is optimized by means of these capacitors. In order to obtain tunable bandwidth in each channel, varactor diodes are located at the orthogonal corners of the proposed resonators. In addition, the proposed resonators have reference patch elements at the lateral arms to provide convenience of varactor diode capacitances, such as perturbation elements. Depending on the capacitances of the varactor diodes, the bandwidths of each channel can be tuned. Furthermore, each channel can be switched off. The designed diplexer has two channels at the center frequencies of 1.8 and 2.6 GHz, which are allocated to 4.5G applications. Three-dB bandwidths can be tuned between 60 and 160 MHz for the first channel and between 150 and 350 MHz for the second channel. Isolation between the output ports is obtained as better than 18 dB in each channel. The designed diplexer was fabricated and measured, and the measured results were consistent with the predicted results. [ABSTRACT FROM AUTHOR]

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A new planar microstrip-fed monopole ultra-wideband (UWB) antenna with dual notched bands has been presented. By employing a simple dual-mode resonator with two symmetrical outer high-impedance lines beside the microstrip feed line of the proposed UWB antenna, two controllable rejection bands with high-frequency selectivity are created. The parametric studies of the proposed structure are explored for the dual band-notched operating mechanism. Finally, the experimental results, including return losses, radiation patterns, and peak gains are shown, declaring that the proposed antenna has good impedance matching performance and radiation pattern properties. [ABSTRACT FROM PUBLISHER]

ABSTRACT A frequency reconfigurable bandpass filter using an electronically tunable dual-mode Substrate Integrated Waveguide (SIW) resonator is presented. Four lumped capacitors as electric tuning elements are loaded near the regions of strongest electric field of TE102 and TE201 modes. The resonant frequency of these two orthogonal modes is tuned by different capacitance values of four lumped capacitors coupled to the SIW resonator. Measured results show that the proposed filter exhibits a tuning range of about 37% from 3.44 to 5 GHz with the total insertion loss variation of 1.85-5.2 dB. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:934-937, 2017 [ABSTRACT FROM AUTHOR]

ABSTRACT: A novel and compact microstrip dual-mode bandpass filter with multi-transmission zeros is designed, fabricated, and measured in this letter. The presented filter consists of a modified square-loop resonator (MSLR) with dual-mode resonant characteristic and an improved input/output defected microstrip structure with a dual-bandgap feature, which is overlapped with the MSLR at the input/output tapping location. Finally, a planar wideband filter with low insertion loss and high selectivity is simulated by the full-wave electromagnetism solver, and verified by our circuit experiment. The measured results of proposed filter have agreed well with the simulated ones, and have shown an excellent electric characteristic with −3 dB fractional bandwidth 33.9% at the mid-band frequency, minimum insertion loss 0.5 dB, maximum return loss better than −20 dB, and four transmission zeros nearby the lower and upper pass-band edges. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:618-621, 2017 [ABSTRACT FROM AUTHOR]

A novel fractal design scheme has been introduced in this paper to generate microstrip bandpass filter designs with miniaturized sizes for wireless applications. The presented fractal scheme is based on Minkowski-like prefractal geometry. The space-filling property and self-similarity of this fractal geometry has found to produce reduced size symmetrical structures corresponding to the successive iteration levels. The resulting filter designs are with sizes suitable for use in modern wireless communication systems. The performance of each of the generated bandpass filter structures up to the 2nd iteration has been analyzed using a method of moments (MoM) based software IE3D, which is widely adopted in microwave research and industry. Results show that these filters possess good transmission and return loss characteristics, besides the miniaturized sizes meeting the design specifications of most of wireless communication systems

Differential techniques are widely used in communication and sensor systems, as these techniques have been shown to improve the performance. This paper shows how differential sensing of permittivity can be conducted in a simple way. For that purpose, a microstrip line loaded with a pair of stepped-impedance resonators is used in two different resonator connections: parallel and cascade. Each resonator is individually perturbed dielectrically so that: 1) when the two individual permittivities are identical, the structure exhibits a single resonance frequency and 2) when the permittivities are different, resonance frequency splitting occurs, giving rise to two resonances (all these resonances are seen in the form of transmission zeroes). The two sensing approaches are successfully validated through electromagnetic simulations and experiments. By virtue of a differential measurement, robustness against changing ambient factors that may produce sensor miscalibration is expected. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM PUBLISHER]

This paper presents a second-order Chebyshev constant fractional bandwidth (CFBW) tunable bandpass filter with compact size and frequency invariant-passband characteristics using tunable external quality factors. The filter is designed using a stub loaded dual-mode resonator and two sets of varactors for tuning the center frequency and the return loss level. The design is featured with the net-type filter of a short grounded-stub so that the CFBW property can be assured. In addition to the conventional design, a pair of varactors is included at the ends of feeding transmission lines to keep the external quality factors constant while tuning. Within the tunable range of the varactors, the proposed filter is tunable from 1.7 to 2.1 GHz with a 5% CFBW. The measurement results show a 20-dB return loss and insertion loss below 2.9 dB over the entire tuning range. [ABSTRACT FROM PUBLISHER]