Search

In this letter, a novel compact tri-band bandpass filter (BPF) with high selectivity is presented. The proposed tri-band performance measure is realized by using eight sets of resonators, i.e., two- and three-section stepped impedance resonators (SIRs). The three-section SIR is designed for determining the three passbands and providing the electric coupling, while the two-section SIR is used for determining each passband respectively and providing the magnetic coupling. Then, coupling structures with two transmission zeros near each passband edge are presented, therefore, the band selectivity of the filter is much improved. The three passband frequencies could be independently designed and tuned. This novel tri-band BPF is fabricated and the measured results are in good agreement with the full-wave simulation results. [ABSTRACT FROM AUTHOR]

A new type of dual-mode planar filter with flexible transmission zeros using slot-line square loop resonator (SSLR) is presented. This resonator is based on the slot-line loop on the ground plane. Four slot-line stepped impedance stubs are loaded in the center loop to achieve compact size and harmonic suppression. Two sizes of slot patches added at the inner corners can split the degenerate modes and adjust the coupling between even and odd modes. A pair of T-shaped feed lines on the top plane can provide flexible source-load coupling, which leads to symmetrical or asymmetrical frequency response. Both the equivalent circuit and coupling matrix analysis methods are utilized to design the dual-mode filter. Two kinds of filters operating at 3.35 and 3.80 GHz with wideband and flexible transmission zeros are designed and fabricated. [ABSTRACT FROM AUTHOR]

In this paper, a novel triple-band microstrip filter with improved out-of-band suppression is presented. The theoretical design of triple-band filter is based on frequency transformation method, which is then realized by a group of triple-band resonators as the building block of the filter. Two open stubs with different lengths are loaded directly in the middle of two resonators to introduce a pair of transmission zeros, which achieves high out-of-band suppression filtering response with no need of cross-coupling. To validate the method, a practical triple-band filter with pass-bands at 3.3-3.4 GHz, 3.5-3.6 GHz, 3.7-3.8 GHz and transmission zeros at 3.1 GHz, 4 GHz is designed and fabricated. [ABSTRACT FROM AUTHOR]

In this paper, the triangular electromagnetic resonators (TERs) is introduced and investigated. The electric mode at lower frequency and magnetic mode at higher frequency, originating from coupling to the electric field and magnetic field, are validated through the measurement in parallel-plate waveguide system, parameter retrieval algorithm and surface currents distributions. Besides, the double negative properties of TERs-wire structures have been validated through both transmission experiment and phase shift experiment. This new resonators with distinct electric resonance as well as magnetic resonance could provide us a new way to design double negative material. [ABSTRACT FROM AUTHOR]

A novel measurement method of parallel-plate waveguide (PPW) system is introduced to detect the characteristics of left-handed metamaterials (LHMs). A sample of LHM composed of triangular open-loop resonator plus wire structures is proposed and measured by using this PPW system. The measurement results are in good agreement with the simulation results. Furthermore, the parametric retrieval algorithm, the calculated negative phase shift and the simulated subwavelength imaging result are given to validate the authenticity of PPW measurement system, which effectively demonstrates the measured transmission passband is indeed a left-handed passband. [ABSTRACT FROM AUTHOR]

A novel dual-band filter using open loop ring resonator (OLRR) and defected stepped impedance resonator (DSIR) is presented in this paper. The OLRR forms one pass on the upper plane, and the DSIR forms the other pass on the lower plane. A proper designed feed structure is analyzed and used, which can provide desired external couplings to the two passes independently. At last, a dual-band filter with cascaded quadruplet (CQ) topology is designed and fabricated, which operates at WLAN bands 2.45/5.25 GHz. The simulated and measured results show good agreements and validate the proposed design method. [ABSTRACT FROM AUTHOR]

A wideband cross coupled bandpass filter making use of square split-ring resonator (SRR) defected ground structure (DGS) and parallel microstrip feed line is presented in this paper. The coupling between a pair of SRR DGS is much larger than that of the conventional SRR, which is fully investigated and applied to the design of wideband cross coupled filter. By extracting the coupling coefficient of various coupling structures and external quality factors of various feed structures, a SRR DGS four-pole filter with center frequency of 2.2 GHz and bandwidth of 20% is designed and fabricated. [ABSTRACT FROM AUTHOR]

Performance of amplifying evanescent wave is investigated on the basis of simulation. Three cases of waveguides loading SRR resonators, strip lines and composite meta-materials are analyzed individually. In certain frequencies, these three kinds of arrays all have the ability of evanescent wave amplification. [ABSTRACT FROM AUTHOR]

A novel dual-mode bandpass filter based on conventional triangular structure is designed in this paper. The filter has the characteristics of compact structure, low insertion loss and so on. Several attenuation poles in the stopband are realized to improve the selectivity of the proposed bandpass filter. The experimented results were in good agreement with simulated results. [ABSTRACT FROM AUTHOR]

A compact dual-band microstrip filter with equal-length split-ring resonators and 0°-feed structure is proposed in this article. The frequency splitting effect of the equal-length SRRs is described in detail. A 0°-feed structure is introduced and applied to realize additional transmission zeros at finite frequencies. The measurement of the filter is in good agreement with the simulation. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1098–1101, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23288 [ABSTRACT FROM AUTHOR]

This paper presents a novel dual-band banpass filter using microstrip open-loop resonators. A new microstrip unit of dual-band bandpass filter is introduced, which can be used as unit element of duan-band filter design. The two open-loop resonators are treated as passband resonator and stopband resonator in analysis, respectively. A five-pole C-band dual-band bandpsss filter has been designed and fabricated. The measured results show a good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A novel design method of dual-band and tri-band band-pass filters is proposed in this paper. A compact loaded open-loop resonator(LOLR) structure is introduced. The resonant frequency response of the resonator is described in detail. A dual-band filter and a tri-band filter are designed with the LOLRs. 0° feed structures are applied to improve the selectivity of the proposed filters. The measurements of the filters are in good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A novel type of dual-band microstrip structure and its equivalent circuit are investigated, which is composed of defected split-ring resonator and interdigital capacitor. The influence of design parameters on the frequency characteristics is discussed, then a dual-band microstrip filter, which has two passbands of 1.8–2.5 GHz and 5.5–5.9 GHz with a transmission zero, is designed and fabricated. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2104–2106, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22673 [ABSTRACT FROM AUTHOR]

A topology of a compact planar microstrip filter with a notched band is introduced, which employs a split-ring resonator defected ground structure (DSRR). Folded short-circuited stubs are used to realise the bandpass filter with good selectivity and out-of-band characteristics. By employing a split-ring resonator defected ground structure, a narrow notched band was introduced to reject the undesired wireless local-area network (WLAN) radio signals. The measured insertion loss is less than 1.6 dB, the return loss is more than 13 dB, and the variation of group delay is less than 0.5 ns throughout most of the two passbands. The width of the narrow notched band is about 1 GHz and the attenuation is more than 25 dB at the centre frequency of 5.4 GHz. [ABSTRACT FROM AUTHOR]