Uniform Impedance Resonator Research Articles

High‐selective wideband bandpass filter with adjustable notched‐band using stub‐loaded resonator

A high-selective microstrip wideband bandpass filter (BPF) with an adjustable notched-band is proposed. First, a pair of open-ended stubs is tap-connected to a λ/2 uniform impedance resonator at two symmetrical locations with respect to its centre, and they are further electrically connected by a microstrip line section. Such an arrangement leads to the emergence of a notched-band owing to the out-of-phase cancellation of two dissimilar signal paths in a wide passband. Secondly, the electrical path connecting the two open-ended stubs is gradually tuned so as to adjust the notched-band to the desired frequency location. Finally, a prototype filter is designed and fabricated, and its measured results are provided to verify the predicted frequency response.

The Design of Wideband Microstrip Bandpass Filter Using Dual Stepped Impedance Stub-Loaded Resonator

In this paper, a uniform impedance resonator (UIR) with a pair of identical stepped impedance open-circuited stubs loaded at two symmetrical positions with respect to its center is presented and analyzed for the design of a wideband micristrip bandpass filter (BPF). With compared to the conventional single open-ended stub loaded in the middle of the UIR or paired uniform stubs located at the two symmetrical position, the proposed resonator has the advantage of providing more freedom to adjust the bandwidth. Meanwhile, the two transmission zeros at both lower and higher sides of the passband ensure the filter has a good roll-off rate at the passband edge.

Design of compact tri‐band bandpass filter using centrally loaded resonators

ABSTRACTTri‐band bandpass filter using centrally loaded resonators is presented in this article. The triple‐passband characteristics are realized by properly controlling the lengths and impedances of the uniform impedance resonator and the stub. To illustrate the concept, two tri‐band filters are designed, fabricated, and measured. Simulated and measured results are found to be in good agreement with each other. The prototype of the tri‐band filters achieve insertion loss of 1.6, 1.9, and 1.9 dB at 2.4, 3.5, 5.8 GHz, 1.2, 1.3, and 1.3 dB at 1.57, 2.45, 5.2 GHz, respectively. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2695–2699, 2013

Full-wave analysis of a compact bandpass meandering resonator filter using method of lines

Full-wave analysis based on the method of lines and the generalized transmission line equations is applied for the design of a small-size wide stopband bandpass filter. The analytical calculation in the direction of propagation and using nonequidistant discretization enables the analysis of the method of lines to be efficient for structures that can be divided into cascaded subsections along the propagation direction of the wave. The proposed filter consists of a pair of meandering uniform impedance resonators and feeding lines. Wide stopband and high selectivity as well as compact size of the filter are achieved due to the effect of multipath between the feeding points and the resonators that leads to suppression of the first and second harmonic of the filter. The modes distribution and the scattering parameters of the designed filter are computed and studied, leading to an achievement of a passband return loss greater than 18 dB and insertion loss about 1.7 dB. The designed filter is fabricated and tested, where good agreement is found between the numerical and experimental results.

Compact Tri-Band Bandpass Filter Based on $\lambda/4$ Resonators With U-Folded Coupled-Line

This letter presents a novel compact microstrip tri-band bandpass filter (BPF) based on $\lambda/4$ resonators. The first and third passbands are realized by coupling the two dual-band $\lambda/4$ stepped impedance resonators (SIRs) with synthesized frequency response. Meanwhile, the second passband in the middle is achieved by introducing the two coupled $\lambda/4$ uniform impedance resonators (UIRs). A non-uniform coupled-line with the U-folded shape on one line is then proposed to independently achieve the dissimilar external couplings as desired in the tri-passbands. In parallel, the quadruplet topology for each band is formulated by introducing an additional weak I/O cross coupling, thereby bringing one pair of transmission zeros at each side of all the triple passbands, In final, a tri-band BPF with the central frequencies of 1.8, 3.5, and 5.8 GHz, and respective fractional bandwidths of 7.0%, 5.0%, and 3.5% is designed and fabricated. The measured results show good consistence with the simulated ones.

Tri-band Microstrip Bandpass Filter Using Dual-Mode Stepped-Impedance Resonator

This letter presents a compact dual-mode tri-band bandpass filter by using a short-circuited stub-loaded stepped-impedance resonator (SIR) and a short-circuited stub-loaded uniform impedance resonator. Also, a hairpin SIR geometry is introduced to miniature the size of this filter while maintaining excellent performance. The use of a short-circuited stub at the central point of the hairpin SIR can generate two resonant modes in two passbands. Its equivalent circuit structure is analyzed by using the even-odd mode theory. For demonstration purposes, a tri-band filter for the applications of the Global Positioning System at 1.57 GHz, Worldwide Interoperability for Microwave Access at 3.5 GHz, and wireless local area networks at 5.2 GHz is designed, fabricated, and measured.

Tri-band Microstrip Bandpass Filter Using Dual-Mode Stepped-Impedance Resonator

This letter presents a compact dual-mode tri-band bandpass filter by using a short-circuited stub-loaded stepped-impedance resonator (SIR) and a short-circuited stub-loaded uniform impedance resonator. Also, a hairpin SIR geometry is introduced to miniature the size of this filter while maintaining excellent performance. The use of a short-circuited stub at the central point of the hairpin SIR can generate two resonant modes in two passbands. Its equivalent circuit structure is analyzed by using the even-odd mode theory. For demonstration purposes, a tri-band filter for the applications of the Global Positioning System at 1.57 GHz, Worldwide Interoperability for Microwave Access at 3.5 GHz, and wireless local area networks at 5.2 GHz is designed, fabricated, and measured.

Multi-Layered Dual-Band Bandpass Filter Using Stub-Loaded Stepped-Impedance and Uniform-Impedance Resonators

The design of multi-layered dual-band bandpass filter using stub-loaded stepped-impedance and uniform-impedance resonators is proposed. The filter is designed to have dual-passband at 2.4, and 5.2 GHz for Wireless Local Area Network (WLAN). The multi-layered filter consists of the stub-loaded stepped-impedance resonator (SL-SIR) on the top layer and the stub-loaded uniform-impedance resonator (SL-UIR) on the bottom layer, that can provide the multi-path propagation to enhance the filter performance and compact circuit size. The proposed SL-SIR and SL-UIR play important roles for controlling the transmission zeros at each first and second passband edges. The measured results are in good agreement with the full-wave electromagnetic simulation results.

Compact dual-band bandpass filter with controllable bandwidths using stub-loaded multiple-mode resonator

A compact microstrip-line dual-band bandpass filter using a stub-loaded multiple-mode resonator is presented. This multiple-mode resonator is formed by loading three stubs (one short-circuited and two open-circuited stubs) in shunt to a simple uniform impedance resonator in the centre and two symmetrical locations, respectively. By properly adjusting the lengths of the three stubs, the first two resonant modes of this multiple-mode resonator can be allocated within the first passband, whereas the third and fourth resonant modes can be allocated within the second passband of the dual-band filter. This results in the formulation of a novel dual-band filter with compact-size and high isolation between passbands by incorporating this multiple-mode resonator with source-load coupling. Two coupling paths are used to control the bandwidth of each passband independently. To illustrate the concept, two dual-band filters of different frequency ratios are designed, fabricated and measured. Simulated and measured results are found to be in good agreement with each other, showing that a rejection level of 15 dB up to more than four times the first passband frequency can be obtained.

Novel UWB Bandpass Filter Using Stub-Loaded Multiple-Mode Resonator

Novel compact ultra-wideband (UWB) bandpass filter (BPF) using stub-loaded multiple-mode resonator (MMR) is presented in this letter. The MMR is constructed by loading three open stubs in a uniform-impedance resonator, i.e., one stepped-impedance stub at the center and two uniform-impedance stubs at the symmetrical side locations. Five modes, including two odd modes and three even modes, could be designed within UWB band, and two transmission zeros generated by the stepped-impedance stub improve the passband selectivity greatly. The letter shows modal resonant frequencies against the step-impedance-stub-loaded parameters, which can control the even modes flexibly, while the odd modes remain the same. A compact planar UWB BPF is simulated, fabricated and measured. The simulated and measured results are in good agreement and show good in-band filtering performance and sharp selectivity.

A Simple Method to Design a Compact Triple-passband Filter Using Novel Coupling Scheme and Multi-Layered Substrate

In this paper, a simple method to design a compact triplepassband filter is presented. The proposed filter structure is mainly composed of two half-wavelength input/output (I/O) terminated microstrip lines and three open-loop uniform impedance resonators (UIRs), which are designed for three different passbands. By properly selecting the coupling position between I/O open-ended microstrip lines and each desired resonator, three passbands can be integrated, and the insertion loss can be improved. In order to achieve compact size, the three UIRs are placed on different layers of the substrate. A filter example operated at 1.575 GHz, 1.8 GHz, and 2.4 GHz for GPS, GSM, and WLAN applications is designed using the proposed concept and then fabricated. Experiment results show a good agreement with the simulated performances.

COMPACT THIRD-ORDER MICROSTRIP BANDPASS FILTER USING HYBRID RESONATORS

In this paper, a novel microwave bandpass fllter structure is proposed. By introducing a metallic via hole, the fllter structure operates as one ‚/2 and two ‚/4 uniform impedance resonators and consequently form a triplet coupling scheme. The equivalent circuit model is analyzed in detail, which shows that there is a transmission zero in the low stopband. Based on that concept, three microstrip fllters are designed, fabricated and measured, respectively. The flrst fllter has no source/load coupling and only one transmission zero is created. By introducing source/load coupling, the second fllter can create three transmission zeros. The third fllter can create a controllable transmission zero in upper stopband. The simulated and measured results agree very well.

DESIGN OF DUAL-BAND BANDPASS FILTERS USING A DUAL FEEDING STRUCTURE AND EMBEDDED UNIFORM IMPEDANCE RESONATORS

In this paper, a simple method and structure to design a dual-band bandpass fllter (BPF) by using a dual feeding structure and embedded uniform impedance resonator (UIR) is presented. In this structure, two passbands can be designed individually and several transmission zeros can be created to improve the band selectivity and stopband performance. The flrst passband is determined by the dual feeding structure and the second passband is determined by the UIR. Moreover, by using the inter coupling in the UIR, the performance of the second passband can be easily tuned without degrading the flrst passband. In order to verify the design concept, two fllter

Design of a Triple-Passband Microstrip Bandpass Filter with Compact Size

This paper presents the triplepassband microstrip bandpass filter (BPF) with compact size. Two sets of the coupled asymmetric stepped impedance resonators (SIRs) and uniform impedance resonators (UIRs) are arranged for generating the triple-passband properties. It is convenient to control the triple-passband properties by tuning the impedance ratio (K) and length ratio (γ) of the asymmetric SIRs. The UIRs are also employed to enhance the coupling between the coupled resonators at 3rd passband. The filter is designed at 2.4/5.2/8.2 GHz and achieves nearly 50% circuit size reduction compared with the previous works. This study provides a simple method to design a triple-passband filter with compact circuit size. Experimental verification is provided, and good agreement has been found between simulation and measurement.

Compact dual-band bandpass filter using defected microstrip structure for GPS and WLAN applications

A modified defected microstrip structure (DMS) for designing a dual-band bandpass filter with independently controlled centre frequencies is presented. The DMS using an F-shaped spurline embedded into a uniform impedance resonator is applied to generate double-resonance characteristics. Based on this theory, a dual-band filter for GPS/WLAN applications has been designed, analysed and fabricated. It is compact and has easy fabrication. Measured results verify the validity of this design methodology. Also, this is believed to be the first report on the DMS in microwave dual-band filter design.

Dual-mode filter design based on uniform or stepped impedance resonator

This article presents a design of compact microstrip dual-mode filter. The design uses dual-mode resonators developed from a uniform or stepped impedance resonator with a load tapped at the middle of the resonator. Four different types of loads can be employed to excite an additional even mode. This kind of dual-mode resonator is applicable in filter design. To validate the new approach, several bandpass filters are designed, fabricated and measured. Measurements have verified the effectiveness of the method.

Reply to “Comments on ‘The Design of Coupled Resonator Bandpass Filter With Stop-Band’”

For original paper see ibid., p.251-253, (2008). For comment see ibid., p.650, (2008). The resonant conditions of uniform impedance resonators (UIR) are only determined by the length of the resonator. As for stepped impedance resonators (SIR), however, both the length and the impedance ratios must be taken into account. Therefore, SIR has more design parameters than UIR. The SIR's spurious frequencies can be easily controlled by choosing proper impedance ratios. In addition, the SIR has a smaller overall electrical size as compared with the UIR at the same center frequency.

Compact microstrip bandpass filter using two‐layer aperture‐coupled resonator‐embedded structure

AbstractA two‐layer microstrip bandpass filter using aperture‐coupled topology is proposed in this article. The filter is composed of two uniform impedance resonators and two stepped impedance resonators located on two stacked microstrip layers, and the couplings between the resonators on the upper layer and those on the lower one are obtained by using three coupling apertures etched on a common ground plane placed between the two layers. With this two‐layer configuration, the proposed filter becomes very compact. To demonstrate the design, a four‐order bandpass filter is designed at 2.33 GHz. Compared with a single layer structure filter, a significant size reduction of about 50% is obtained. Furthermore, a stop‐band is extended to 8 GHz (3.43 f0) with a rejection better than −20 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2357–2360, 2008; Published online in Wiley InerScience (www.interscience.wiley.com). DOI 10.1002/mop.23680

Design of a multilayered dual‐band bandpass filter with transmission zeros

AbstractIn this article, a dual‐band bandpass filter (BPF) using the multilayered structure is presented. The BPF consists of a pair of uniform impedance resonators on the top layer and a pair of step‐impedance resonators on the middle layer. By using the multilayered structure, the multitransmission zeros located near the passband edges, which is introduced by the crosscoupling effect, can be created to improve the filter selectivity. In addition, the bandwidths of the two passbands (2.4/5.2 GHz) can be tunable by adjusting the coupling gap distance between the resonators. The fabricated filter has a very compact size. Experimental results of the fabricated filter are well agreed with the simulation results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2010–2013, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23585

Miniaturised dual-mode microstrip bandpass filters with wide upper stopband

Dual-mode bandpass filters with miniaturised size and wide upper stopband are presented here. The miniaturisation is realised by resorting to the proposed unilateral and bilateral stepped-impedance open stubs. With adequate design, the loaded capacitance values of a stepped-impedance open stub can achieve 3.2 times the counterpart of a uniform impedance resonator. In addition, the proposed resonator is featured of an additional transmission zero in the upper stopband. To establish the necessary capacitive input/output couplings, filters with only one coupling arm is demonstrated and an enhanced rejection level of the upper stopband is obtained. Results show that the proposed filters cannot only reduce the circuit size up to 68%, but also achieve wide upper stopband as well.