Search

In this paper, a novel dual‐band wideband bandpass filter (BPF) based on transversal signal‐interaction concepts with a wide upper stopband is proposed and investigated. The designed specification of two passbands can be managed and satisfied based on the independent controllable fractional bandwidth of the two passbands and the centered frequencies. The centered frequencies of dual‐band BPF are, respectively, 0.79 GHz (ƒ1) and 1.24 GHz (ƒ2) with 3 dB fraction bandwidths of 26.54% and 11.3%. Two transmission paths consisting of coupled stub‐loaded square ring resonators and anti‐coupled shorted lines are used to realize signal cancellation of multiple transmission path signal transmission from Port 1 to Port 2. Eleven transmission zeros (TZs) modify harmonic suppression up to 10 ƒ1 with stopband rejection higher than 15 dB. Butterworth lumped notch network and step impedance resonator (SIR) are also utilized to improve the selectivity and harmonic suppression. A compact filter with a circuit size of 0.08λg × 0.08λg is implemented and tested. Good agreement between simulation and measured results verifies the reliability of the designing scheme. [ABSTRACT FROM AUTHOR]

In this paper, a novel dual-band wideband bandpass filter (BPF) based on transversal signal-interaction concepts with a wide upper stopband is proposed and investigated. The designed specification of two passbands can be managed and satisfied based on the independent controllable fractional bandwidth of the two passbands and the centered frequencies. The centered frequencies of dual-band BPF are, respectively, 0.79 GHz (ƒ1) and 1.24 GHz (ƒ2) with 3 dB fraction bandwidths of 26.54% and 11.3%. Two transmission paths consisting of coupled stub-loaded square ring resonators and anti-coupled shorted lines are used to realize signal cancellation of multiple transmission path signal transmission from Port 1 to Port 2. Eleven transmission zeros (TZs) modify harmonic suppression up to 10 ƒ1 with stopband rejection higher than 15 dB. Butterworth lumped notch network and step impedance resonator (SIR) are also utilized to improve the selectivity and harmonic suppression. A compact filter with a circuit size of 0.08λg X 0.08λg is implemented and tested. Good agreement between simulation and measured results verifies the reliability of the designing scheme.

In this article, waveguide dual-band filter and diplexer working on W-band are synthesized through cascading mixed TE301- and TE102-mode cavities as well as TE101-mode resonators. Based on the discussion of top resonance modes in single cavity, the TE301&TE102 dual-mode resonator which features oversized dimension, technological insensitivity and high Q-factor is the strong candidate for designing high-frequency filters and diplexers. For dual-band filter, such dual-mode resonator can be shared by both bands as T-junction, and each band can be independently controlled. Besides, a W-band diplexer is proposed based on the analogous method. Two extra zeros have also been generated for each channel with adopting the singlet concept. Finally, the filter and diplexer prototypes are machined by CNC-milling. The filter has obtained 3-dB FBWs of 4% (86.7–90.2 GHz) and 6.3% (96.7–103 GHz), low insertion losses (ILs) of -0.9 dB and -0.5 dB, as well as less than -16 dB return loss, respectively. The diplexer has achieved 3-dB FBWs of 4.9% (86.3–90.6 GHz) and 6.5% (96.9–103.4 GHz), low ILs of -0.7 dB and -0.4 dB, high insolation with more than 40 dB, respectively. All the experimental results including transmission zeros on out-of-band are very close to the simulations in the full band. The performance of dual-band filter and diplexer is highlighted comparing with the reported ones too. [ABSTRACT FROM AUTHOR]

A tunable absorptive bandpass filter with two transmission zeros is presented. A lowpass absorptive filter prototype consisting of a matching section and a m‐drive filter section is established based on image parameter method, and the filter elements are easily derived through the image impedance with the required return loss and transmission zeros. Moreover, the two transmission zeros are controlled by adjusting the parameters of the m‐drive filter section. A distributed tunable absorptive bandpass filter is realized based on the proposed lowpass filter prototype. The fabricated filter shows a return loss of 21–25 dB and an insertion loss of 2.1–2.8 dB at the center frequency within the tuning range of 1.35–1.58 GHz. [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 study, a novel dual-band bandpass coaxial cavity filter with large design freedoms for center frequencies and bandwidths is proposed by introducing F-shaped dual-mode resonators. Each F-shaped dual-mode resonator is capacitively loaded with two tuning screws for simultaneously tuning two frequencies. A dual-iris structure is implemented for the couplings between the two dual-mode resonators, with two screws applied to enhance the couplings. A dual-disc capacitive coupling is implemented at the input and output ports. By introducing these structures, the frequencies and bandwidths of the two passbands can have large design freedoms. A third-order dual-band filter at 0.845 GHz/1.790 GHz with bandwidths of 12 MHz/26 MHz is also designed, fabricated, and measured. Low insertion losses of 0.4 dB and 0.35 dB are achieved at the passbands. In comparison with planar dual-band bandpass filters, the filter presented in this study offers lower insertion losses and more convenience in filter tuning.

This article presents a novel dual-band bandpass filter based on cylinder dielectric resonators, where the dielectric mode TE01δ is exploited to generate the first passband, and the two degenerate modes HEH11 are used to generate the second passband. In order to achieve the needed couplings between the input/output port and the TE01δ/HEH11 modes, a probe with both a straight and a curved section is designed. The needed inner couplings between modes of contiguous cavities are instead obtained by using inductive irises and capacitive probes. A systematic design procedure is provided for achieving the center frequencies and bandwidths with large design freedoms. To validate the methods, a dual-band filter working at 2.249 GHz and 2.607 GHz with bandwidths of 32 MHz, is designed and fabricated. The Filter shows low insertion loss, high rejection and compact dimensions. Measured results demonstrate the feasibility of the proposed approach.

A dual-band bandpass plasmonic filter based on quarter-wavelength effective localized surface plasmon resonators (ELSPRs) is proposed in this work. Compared with conventional microstrip resonators, ELSPRs have a larger unloaded quality factor and compact size, which can be flexibly designed. Since the harmonics of quarter-wavelength ELSPRs are located only at odd times of their dominant mode frequency, we can not only miniaturize the filter but achieve excellent out-ofband rejection performance. For demonstration, we design and fabricate a dual-band bandpass plasmonic filter, whose size is only 0.0396 λ20, the center frequency is 3.1 GHz and 3.6 GHz, and the relative bandwidth is 10.7% and 7.7% respectively. Measurement results show excellent agreement with the simulations. Our results provide a route for realizing ultra-compact and highperformance functional devices for the fifth generation (5G) applications. [ABSTRACT FROM AUTHOR]

In this brief, a quad-mode cylindrical cavity dual-band bandpass filter (CCDBPF) is proposed. Two stepped cylinders are located at the top and bottom of the cylindrical cavity. Two low-order resonant modes are generated because of two stepped cylinders, and they constitute the first passband. Two high-order modes are the low-order modes of the cylindrical cavity itself, which constitute the second passband. The center frequencies of two passbands are 1.61 GHz and 2.61 GHz, respectively. Two passbands can be independently adjusted. The first passband can be adjusted from 1.55 to 1.67GHz with insertion loss of 0.13-0.15 dB. The second passband can be adjusted from 2.48 to 2.67 GHz with low insertion loss of 0.1-0.2dB. The frequency selectivity is improved because of four transmission zeros (TZs) at 1.49 GHz, 1.89 GHz, 2.52 GHz, and 2.89 GHz. Since the stepped cylinders introduce a low-frequency passband, the miniaturization of the CCDBPF is realized. Finally, the CCDBPF is fabricated and measured. The measured frequency responses are coincident with the simulated results. [ABSTRACT FROM AUTHOR]

Compact substrate‐integrated waveguide (SIW) diplexers and dual‐band bandpass filter (BPF) with widely separated passbands and wide‐stopband are proposed for the first time based on half‐mode substrate‐integrated rectangular cavity (HMSIRC). Thanks to the dual‐mode cavities and two respective channels, the frequencies and couplings of the two passbands can be flexibly controlled. To conquer the limitation of conventional full‐mode cavity, the use of HMSIRC could intrinsically reject TE201 mode and many higher‐order even modes, simultaneously realizing wide‐stopband and widely separated passbands based on TE101 and TE102 modes. Moreover, the properly arranged internal coupling windows, which could intrinsically suppress the specific unwanted modes by sufficiently employing the existing design degrees of freedom, help further separate the two passbands and extend the stopband. The passband and stopband responses are systematically analyzed for different frequency ratios with the realizable frequency ratio and stopband bandwidth up to 1.91 and 2.65f1, respectively, which supplies the design guideline for SIW diplexers and dual‐band BPFs with widely separated passbands and wide‐stopband. Two SIW diplexers and an SIW dual‐band BPF with frequency ratios of 1.72, 1.85, and 1.72 are synthesized and designed for demonstration, realizing the rejection levels and stopband bandwidths of 20 dB/2.34f1, 35 dB/2.36f1, and 20 dB/2.6f1, respectively. [ABSTRACT FROM AUTHOR]

In this brief, a novel on-chip dual-band bandpass filter (D-BPF) with two independently controllable transmission zeros (TZs) is proposed. Based on resonators transformation, the schematic and design procedure of the filter are presented. Using even-/odd-mode analysis, analytical equations are used for demonstration of the theory. As an example, a 3.32/5.17-GHz D-BPF with 3-dB fractional bandwidth (3-dB FBW) of 25.45%/14.20% for 5G applications is designed, fabricated, and measured. The size of the filter in low-temperature cofired ceramic (LTCC) is only 11.4 mm * 6 mm * 0.94 mm. The filter has been successfully measured with the minimum insertion loss of 1.38/1.53-dB and high return loss of 28/23-dB at the center frequency. [ABSTRACT FROM AUTHOR]

A compact dual‐band bandpass filter based on the substrate integrates suspended line platform is proposed in this letter. The design is implemented using low‐cost FR‐4 material, while the loss can be reduced by 3D metal connections with substrate cutout. 0.97 dB/1.6 dB improvement of insertion loss is achieved and verified at 3.45 GHz/4.9 GHz. By paralleling quarter wavelength step impedance resonators with different operating frequencies, two paths formed between source and load. Both bandwidth and location of transmission zeros can be adjusted independently. Two stubs are added working not only as feed structure but also as a stop band resonator, which can provide 20 dB out‐of‐band suppression up to 4.4f0. The obtained performances are good enough to compare with the state of art, though very low‐cost FR‐4 materials are used. [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]

This paper presents a series of novel designs for dual-band bandpass filters (BPFs) with excellent in-band and out-band filtering performances. By imbedding the spiral-line resonator into the coupling open-loop structures and adjusting the symmetrical structure, the second-order quad-mode BPFs are designed and then the fourth-order oct-mode dual-band BPFs. The final two designs possess eight resonant modes in the passband and also four/eight transmission zeros in the stopband, achieving a high transition-band selectivity with the roll-off rate over 1000 dB/GHz, broad out-band rejection from 1.5 GHz to 5.3 GHz (lower than 30 dB), and strong isolation between dual bands with the suppression level of 30 dB, operating at 3.2/3.4 GHz and 3.2/3.5 GHz respectively. Measured results agree well with simulations and prove the validity of the asymmetry feeders for multi-transmission-zero characteristics. [ABSTRACT FROM AUTHOR]

A novel method to design compact wideband dual-band substrate integrated waveguide (SIW) bandpass filters (BPF) is proposed in this paper. By loading a novel beeline compact microstrip resonant cells (BCMRCs) with band-gap characteristics on top layer of SIW, two wide passbands separated by a stopband are generated. In order to enable the filter to have lower reflection coefficients in the two passbands, we use a tapered gradient line embedded with rectangular slots and loaded open stubs as the transition structure from microstrip line to SIW. The wideband dual-band BPF (DBBPF) is fabricated. The lower-band and upper-band fractional 3-dB bandwidths are 58.2% and 22.6%, while the measured minimum insertion losses (ILs) are 0.7 and 0.92 dB, respectively. The stepped-impedance openloop ring resonator (SIOLRR) is introduced in order to improve the selectivity of the filter. The wideband DBBPF with SIOLRR is studied, simulated and measured. Two transmission zeros are generated in the stop band between the two passbands. Good agreement between simulated and measured results can be obtained. [ABSTRACT FROM AUTHOR]

This article presents a dual-band bandpass filter based on the double-sided spoof surface plasmon polaritons-line. The whole structure consists of a dual-band filtering part and two SSPPs lowpass filtering parts. Simulated results show that the proposed dual-band bandpass filter has an excellent dual-band filtering performance and wide upper band suppressions. Simulated bandwidths of two passbands are 41% (2.36–3.58 GHz) and 13.9% (6.7–7.7 GHz). It can realize the suppression of $S_{21}$ below −40 dB from 9.6 to 39.7 GHz. A prototype has been fabricated and measured. Measured results are in a good agreement with simulated ones, which validates our design concepts and methods. The proposed dual-band bandpass filter will have significance in microwave device designing, especially in the plasmonic device in microwave frequencies. [ABSTRACT FROM AUTHOR]

A tunable bandpass filter with switchable single‐/dual‐band responses is presented. The single‐band to dual‐band transformation is achieved by controlling frequencies of poles in a passband. The frequencies of poles are adjusting by using a coupled structure with two coupling capacitors. A filter with both 4‐pole single‐band and 2‐pole dual‐band characteristics is built on a Duroid substrate with εr = 3.0 and h = 30 mils. The tuning of the center frequency and the passband transformation are done using silicon varactor diodes. In the 4‐pole single‐passband mode, a center frequency tuning of 1.0 to 1.4 GHz is achieved with 1‐dB bandwidths of 150 to 198 MHz. The 2‐pole dual‐band bandpass filter mode has the center frequency tuning of 1.0 to 1.29 GHz (low‐band) and 1.4 to 1.58 GHz (high‐band). The application areas are in wideband cognitive radios. [ABSTRACT FROM AUTHOR]

Folded quad-mode stub-loaded loop resonators (QMSLLRs) are proposed for realizing both bandpass and dual-band bandpass filters with compact dimensions. The QMSLLR is a folded square loop loaded with four short stubs, providing structure symmetry in both transversal and longitudinal directions. Determined by the lengths of the loaded stubs, the four resonant frequencies as analyzed with even-odd mode method can be either distributed in one passband with equal space, or in two passbands with a guard band in between, for realizing a single-band bandpass filter or a dual-band bandpass filter, respectively. For both the input and output couplings, two perpendicular feeding lines are parallel coupled to the QMSLLR at one corner. The measure results prove that the structure is suitable for the design of a medium band or even narrow band bandpass filters with compact dimensions. [ABSTRACT FROM AUTHOR]

In this article, a compact dual‐band bandpass filter (BPF) is studied and designed by utilizing a modified hexagonal split ring resonator (H‐SRR). The modified H‐SRR consists of a classical H‐SRR loaded by an open‐stepped impedance stub and a grounding via located at the symmetrical plane of the resonator. The proposed BPF operates at 2.5 and 4.83 GHz. Its advantages include simplicity of design, high rejection level due to transmission zeros, and low insertion loss. In addition, the size of the circuit occupies only 142.6 mm2. A good agreement is obtained between measurement and simulation results. [ABSTRACT FROM AUTHOR]

To alleviate the nonuniform error distribution and slow convergence caused by the uncertainty of sample selection in the training process of artificial neural networks, a semisupervised radial basis function neural network (SS-RBFNN) model with a new sampling strategy is proposed for parametric modeling of microwave components in this article. After evaluating the current training performance, the new sampling strategy selects suitable training samples to ensure each subregion of the whole sampling region with the same level of training and testing accuracy. Meanwhile, the proposed SS-RBFNN simplifies the modeling process to further enhance the modeling accuracy and efficiency. Two numerical examples of a slow-wave defected ground structure dual-band bandpass filter and a microstrip-to-microstrip vertical transition are employed to verify the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

Multi-band and all-band absorptive filters can greatly promote the miniaturization of radio frequency (RF) communication systems. However, the existing absorptive multi-band filters have problems such as large size, narrow passband, high insertion loss, and low RF signal absorption capacity. Herein, a new all-frequency absorptive dual-band bandpass filter (BPF) is proposed by combining an N-shaped microstrip coupler with T-shaped transmission line absorption branches. The N-shaped microstrip coupler can flexibly implement the dual-band bandpass filtering of RF radio frequency (RF) signals in a compact structure. The T-shaped transmission lines can effectively absorb the stopband signals reflected from the N-shaped coupler at full frequency. The theoretical and experimental results show that the 3-dB fractional bandwidths (FBWs) of the proposed BPF with a size of 0.41 λ g × 0.20 λ g are 60.5 % at 1.3 GHz and 13.3 % at 4.1 GHz, respectively, and the return losses in all frequency are greater than 10 dB, indicating that the filter has the characteristics of wide passband, small size, and all-frequency absorption of reflected bandstop signals. In short, the combination of N-shaped coupler and T-shaped transmission line provides a way to achieve an all-frequency absorptive dual-band BPF with a small size, wide passband and low return loss. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic 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.)

Based on a novel microstrip terminated cross-shaped resonator (TCSR), the dual-band bandpass filters (DB-BPFs) with fixed and reconfigurable bandwidths are proposed in this brief. In addition to the basic TCSR’s three poles and four zeros, the extra four poles and three zeros can be introduced with the help of a pair of symmetrical parallel-coupled lines and open-ended stubs. Therefore, a planar DB-BPF with multiple transmission poles and zeros can be realized. To achieve the reconfigurable bandwidths, a capacitor is inserted into the basic TCSR’s lower stub. It is found that the lower bandedge of the first passband can be tuned while the other three bandedges are kept unchanged. Two prototypes, including fixed-bandwidth filter (Filter I) with 3-dB fractional bandwidths (FBWs) of 20.8% and 17.3%, and reconfigurable-bandwidth filter (Filter II) with 3-dB FBW variation from 22.5% to 34.7% for the first passband and 19.8% for the second passband, are designed, fabricated, and experimentally characterized. The experimental characterizations of these two filters verify the proposed design. [ABSTRACT FROM AUTHOR]

A simple and effective method to design a dual-band bandpass filter with high isolation and wide stopband is presented and validated using symmetric open-circuited stub-loaded resonators. By adjusting the electric length and the ratio of characteristic admittance of the resonators, the first two resonant frequencies are identical, but the higher order resonant frequencies dispersed in the upper stopband to extent the bandwidth of stopband. Two transmission zeros are introduced to obtain high isolation and selectivity between the two passbands by placing them in the appropriate position. Proper feeding position is selected to further improve the attenuation of stopband. The measured results highly agree with the simulated one. Measured results demonstrate the isolation level of 40 dB, attenuation of larger than 28 dB, and a wide stopband.

This paper proposes a novel design methodology for dual-band Doherty power amplifier (DPA) with a novel dual-band bandpass filter and quad-section stepped impedance resonators. This design rejects the annoying frequencies of the second and third harmonics in the dual-band and contributes greatly to efficiency improvement of DPA. The methodology is validated with the design, simulation, implementation and experimentation of a 10 W GaN-based DPA for global system for mobile communications and worldwide interoperability for microwave access (WiMAX) applications at 1.84 GHz and 3.5 GHz, respectively. In the measurement results, the DPA achieves a drain efficiency (DE) of 55.5% with an output power of 38.2 dBm and power gain is 16.2 dB at the 6.1 dB output power back-off (OBO) from a saturated output power at 1.84 GHz. Furthermore, the DPA achieves a DE of 46.2% with an output power of 36.15 dBm, and power gain is 10 dB at the 6.1 dB OBO at 3.5 GHz. Using a10-MHz 16-QAM signal at 1.84 GHz and a 5-MHz WiMAX signal at 3.5 GHz, the linearity results show an adjacent channel leakage ratio of − 46.9 and − 44.3 dBc with the average output power of 37.6 and 36.1 dBm at 1.84 and 3.5 GHz, respectively. [ABSTRACT FROM AUTHOR]

A novel dual‐band bandpass filter (BPF) based on a single triple‐mode ring resonator is proposed. The proposed BPF could provide three transmission poles for each passband to improve operating bandwidth. Meanwhile, seven transmission zeros are achieved at the stopband to improve the selectivity. The proposed dual‐band BPF was designed, fabricated and tested. The measured results are in good agreement with the simulated values.

A simple and planar design structure for dual-band bandpass filter (BPF) with multiple transmission poles and zeros is proposed in this brief. According to frequency response transformation, two passbands are realized on both sides of the operation frequency. Sharp selectivity and high isolation level with eight transmission poles and seven transmission zeros are achieved just by employing three-section coupled lines and three short-circuit stubs. Besides, the analytical (closed-form) extraction process for the transmission poles and zeros of the proposed dual-band BPF is presented based on the rigorous scattering-parameters theory and the even- and odd-mode analysis method. A prototype for the dual-band BPF with 3-dB fractional bandwidth of 41.1% and 19.0% is designed and fabricated. The measured and simulated results are in good agreement to verify the validity of the proposed design principle. [ABSTRACT FROM PUBLISHER]

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 1.8GHz and 2.4GHz 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 0.19dB for 1.8GHz and 0.32dB for 2.4GHz. Moreover return losses are better than 43.2dB and 40.6dB for 1.8GHz and 2.4GHz, respectively. The proposed filter has a size of mm2. This microstrip filter is fabricated on RT/Duroid6010 substrate with dielectric constant 10.8 and thickness 1.27mm and its equivalent circuit is also offered. The measured results exhibit good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

Compact dual-band bandpass filters with stepped-impedance conductor-backed asymmetric coplanar waveguide resonators are proposed, and synthesis formulas are derived to facilitate the design. By using an asymmetric topology, two additional transmission zeros are obtained. To further improve the selectivity, an embedded coplanar waveguide resonator is proposed to achieve two independently controllable transmission zeros. Two dual-band bandpass filters are designed and fabricated. The measured results validate the proposed design.

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]

We have developed two high-order high-temperature superconducting (HTS) dual-band bandpass filters (BPFs) with a receiver subsystem for future mobile communication systems. They feature stub-loaded hair-pin resonators with two types of microstrip lines between them. One has a six-pole design, and the other has an eight-pole design. Both were designed to operate at 2.15 GHz with a 43-MHz (2%) bandwidth for the lower passband and at 3.50 GHz with a 70-MHz (2%) bandwidth for the upper one. They were fabricated using YBa 2 Cu 3 O y thin film on a CeO 2 -bufferd r-Al 2 O 3 substrate. The measured results for both filters agree well with the simulated ones. The HTS dual-band BPF receiver subsystem uses a pulse tube cryocooler and a wideband low noise amplifier (LNA). We measured the frequency response of the six-pole dual-band BPF with and without a wideband LNA with a gain of 10 dB. The measured return losses were close. [ABSTRACT FROM AUTHOR]

A novel compact dual-band bandpass waveguide filter is presented in this paper. H-plane metal inserts with complementary split-ring resonators are implemented as resonating elements in the standard (WR-90) rectangular waveguide. Design starts from the models of the waveguide resonators with two resonant frequencies (9GHz and 11GHz) using a single flat or folded metal insert. Further, folded inserts are used for the second-order dual-band filter design. The equivalent circuits are proposed for the considered waveguide resonators and filter. A good agreement of the amplitude responses obtained for three-dimensional electromagnetic models and microwave circuits is achieved. Finally, compact dual-band bandpass waveguide filter is proposed as a novel solution using miniaturized inverters for both central frequencies. Compact filter model is further modified in order to obtain solution customized for easier fabrication. For the compact filter model, amplitude response is experimentally verified. The required filter response is preserved, as verified by a good agreement of the results obtained for the original dual-band filter and for the compact filter solutions. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel coupling matrix synthesis method for dual-band bandpass filter is presented in this article. The output admittance poles and zeros of the single-band filter prototype are firstly obtained and then transformed into dual-band prototype. Then the coupling matrix with predefined topology is optimized according to these poles and zeroes directly. This method can be achieved with no need to construct the characteristic function of dual-band filter and reconfigure the coupling matrix. Symmetric and asymmetric dual-band bandpass filter coupling matrix synthesis has been carried out to illustrate and validate this method. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:603-606, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents, a novel dual-band bandpass filter based on λ/4 uniform impedance resonators (UIRs). The design consists of four λ/4 UIRs, two for each band. The λ/4-resonators are coupled through alternate J/K-inverters. A weak input-output coupling is introduced to add pair of transmission zeros outside each passband, which improves the cut-off of the filter. The filter is designed for Wi-Fi 2.4 and 3.6 GHz bands. The filter is designed in FEKO electromagnetic simulator using FR-4 substrate having dielectric constant 4.4 and thickness of 1.6 mm. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2758-2761, 2015 [ABSTRACT FROM AUTHOR]

In this paper, A high selective dual-band bandpass filter was proposed using a dual-mode ring resonator with two short-circuited stubs. For dual-mode resonance, the ring resonator is directly connected with non-orthogonal feed-lines via coupling capacitors. Two short-circuited stubs which are unequal lengths are simultaneously placed at two corners along the two symmetry plane of the ring resonator in order to obtain dual-band responses. Because the feeding angle perturbated ring resonator of the proposed dual-band bandpass filter has the symmetrical structure, Even/Odd mode analysis can be well applied to extract the scattering parameters and transmission zero frequencies. The proposed dual-band bandpass filter was designed and fabricated for WLAN(Wireless Local Area Network) application of IEEE 802.11n standard. The measured results showed a good agreement with the simulation results, and it should be well applied not only for WLAN applications but also for any other communication systems. [ABSTRACT FROM AUTHOR]

A novel compact dual-band bandpass filter (BPF) based on short stub-loaded stepped impedance resonator (SSL-SIR) and a pair of tri-section stepped impedance resonator (T-SIR) is presented. The dual-band BPF can be divided into two sub filters. The upper sub filter creates the first passband centered at 2.4 GHz, and the lower sub filter generates the second passband centered at 3.5 GHz. The two passbands can be controlled separately and have almost no mutual influence between each other. The structure of the filter is miniaturized and a wide stopband performance is also achieved by introducing SIR. The simulated and measured results are both presented and show good agreement. [ABSTRACT FROM AUTHOR]

This paper discusses a novel multi-stub-loaded stepped-impedance resonator (MSLSIR) with a specific feeding structure. The fundamental and higher order modes of resonant frequencies of the stepped-impedance resonator are key parameters involved in the design of a dual-band bandpass filter (DBPF). However, since resonant frequencies are dependent on each other, the overall structure is not compact. The proposed MSLSIR has the advantage of flexible control over one resonant frequency while the other frequency is fixed. Furthermore, the utilization of isosceles right-angled triangular (IRT) and short-circuited stubs as loaded elements improves size miniaturization of DBPF when a low permittivity substrate is used. The analysis of the IRT stub is based on the coupling impedance formulas derived by integration of the associated Green's function. As an application, a DBPF is presented, which operates at 3.5 and 5.2 GHz, corresponding to the WiMAX and WLAN applications, respectively. In addition, a good stopband rejection, up to $$3\hbox {f}_{1}$$ , is obtained using the defected ground structure technique. An overall good agreement between the calculated, simulated and measured results is observed, thereby confirming the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a novel dual-band bandpass filter based on subwavelength compound metallic grating deposited on the waveguide structure by using the finite-difference time domain (FDTD) method. The compound metallic grating is constructed by carving a groove on the top surface of every metal strip. The designed structure generates two remarkable transmission peaks with a dip in-between at normal incidence. Two transmission peaks with narrow bandwidth and high transmission depth is attributed to the existence of grooves in the designed structure. We research the implied physical mechanism of two resonance peaks and one dip by investigating the effect of different structure parameters on transmission spectrum and the electromagnetic field distributions at the location of resonance. It is found that the two resonance peaks are determined by different hybrid modes of F–P like resonance, waveguide resonance mode and SPP mode. Besides, angularly resolved spectra are presented to further reveal physical mechanism of two resonance peaks. This work can be used to develop a dual-band bandpass filter in the telecom wavelength range. [ABSTRACT FROM AUTHOR]

A compact dual-band bandpass filter based on a modified stepped-impedance resonator is presented in this article. The conventional low-impedance stub of stepped-impedance resonator is replaced by a closed rectangular loop. The proposed filter consists of two pairs of proposed novel stepped-impedance resonators, one of which is embedded in the other one to obtain two passbands. Five transmission zeros can be generated near the passbands for enhanced frequency selectivity and band-to-band isolation. The center frequencies and bandwidths of the two passbands can be controlled by adjusting the geometric dimensions of the proposed stepped-impedance resonator. To demonstrate the proposed method, a 2.4-/5.2-GHz dual-band bandpass filter for Wireless Local Area Networks (WLAN) application has been designed, fabricated, and measured. The circuit only occupies 0.07λg× 0.09λg. [ABSTRACT FROM AUTHOR]

The first substrate integrated waveguide dual‐band bandpass filter with wide‐stopband performance is presented. This filter is synthesised and designed with fourth‐order Chebyshev responses and identical fractional bandwidths for the two passbands centred at 12 and 16 GHz. Multiple spurious resonances have been intrinsically suppressed by introducing the harmonics‐staggered technique and the centred coupling windows. Good agreements can be observed between the measured and simulated results, and better than 25‐dB rejection level up to 2.05f1 has been successfully achieved. [ABSTRACT FROM AUTHOR]

Based on a short stub-loaded stepped-impedance resonator, a novel compact microstrip bandpass filter with controllable passband center frequencies is presented. To obtain dual-passband characteristics, dual-mode short stub-loaded stepped-impedance resonator and novel quad-pole-splitting techniques are investigated. The single passband is split into two with a notch when two resonators are employed, and dual passbands of a close band could be realized. It was found that the filter exhibits two desirable close passbands, an adjustable fractional bandwidth, and wide upper-stopband response. Moreover, the compact size of the proposed structure can be achieved. Good agreement between the measured and simulated results is shown. [ABSTRACT FROM PUBLISHER]

Based on open-loop resonators (OLRs), an independently tunable dual-band (ITDB) bandpass filter (BPF) is presented in this paper. The top layer of the proposed ITDB-BPF is composed of transmission feed lines and OLRs in a stepped-impedance resonator (SIR) structure. The bottom layer is constructed by OLRs in an asymmetrical SIR with a defect-grounded structure. To obtain the required frequencies and bandwidths, the sizes of resonators and feed lines are realized by defining the coupling coefficients and the external quality factors. As to the proposed ITDB-BPF, the first center frequency is set to be 2.45 GHz for Wireless Local Area Network systems. The second center frequency is selected to be 3.5 GHz for a Worldwide Interoperability for Microwave Access systems. The measurement results show that the insertion losses are 2.9 and 2.6 dB for 2.4 and 3.5 GHz, respectively. The minimum return losses are 14.5 dB for 2.4 GHz and 22.8 dB for 3.5 GHz. The stopband rejections of the lower band from dc to 1.84 GHz and the upper bands from 4.34 to 6 GHz are both greater than 30 dB. The center frequencies of the two passbands can be tuned independently by adjusting different resonators which makes the design of dual-band BPF more flexible than conventional ones. [ABSTRACT FROM PUBLISHER]