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Topic

Stopband

About: Stopband is a(n) research topic. Over the lifetime, 6710 publication(s) have been published within this topic receiving 82087 citation(s).


Papers
More filters
Journal ArticleDOI
Abstract: In this paper, a new approach for the development of planar metamaterial structures is developed. For this purpose, split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) coupled to planar transmission lines are investigated. The electromagnetic behavior of these elements, as well as their coupling to the host transmission line, are studied, and analytical equivalent-circuit models are proposed for the isolated and coupled SRRs/CSRRs. From these models, the stopband/passband characteristics of the analyzed SRR/CSRR loaded transmission lines are derived. It is shown that, in the long wavelength limit, these stopbands/passbands can be interpreted as due to the presence of negative/positive values for the effective /spl epsiv/ and /spl mu/ of the line. The proposed analysis is of interest in the design of compact microwave devices based on the metamaterial concept.

1,265 citations

Journal ArticleDOI
16 Jul 1998-Nature
Abstract: The ability to confine and control light in three dimensions would have important implications for quantum optics and quantum-optical devices: the modification of black-body radiation, the localization of light to a fraction of a cubic wavelength, and thus the realization of single-mode light-emitting diodes, are but a few examples1,2,3. Photonic crystals — the optical analogues of electronic crystal — provide a means for achieving these goals. Combinations of metallic and dielectric materials can be used to obtain the required three-dimensional periodic variations in dielectric constant, but dissipation due to free carrier absorption will limit application of such structures at the technologically useful infrared wavelengths4. On the other hand, three-dimensional photonic crystals fabricated in low-loss gallium arsenide show only a weak ‘stop band’ (that is, range of frequencies at which propagation of light is forbidden) at the wavelengths of interest5. Here we report the construction of a three-dimensional infrared photonic crystal on a silicon wafer using relatively standard microelectronics fabrication technology. Our crystal shows a large stop band (10–14.5 μm), strong attenuation of light within this band (∼12 dB per unit cell) and a spectral response uniform to better than 1 per cent over the area of the 6-inch wafer.

1,026 citations

Journal ArticleDOI
Abstract: This paper presents a novel photonic bandgap (PBG) structure for microwave integrated circuits. This new PBG structure is a two-dimensional square lattice with each element consisting of a metal pad and four connecting branches. Experimental results of a microstrip on a substrate with the PEG ground plane displays a broad stopband, as predicted by finite-difference time-domain simulations. Due to the slow-wave effect generated by this unique structure, the period of the PBG lattice is only 0.1/spl lambda//sub 0/ at the cutoff frequency, resulting in the most compact PEG lattice ever achieved. In the passband, the measured slow-wave factor (/spl beta//k/sub 0/) is 1.2-2.4 times higher and insertion loss is at the same level compared to a conventional 50-/spl Omega/ line. This uniplanar compact PBG (UC-PBG) structure can be built using standard planar fabrication techniques without any modification. Several application examples have also been demonstrated, including a nonleaky conductor-backed coplanar waveguide and a compact spurious-free bandpass filter. This UC-PBG structure should find wide applications for high-performance and compact circuit components in microwave and millimeter-wave integrated circuits.

819 citations

Journal ArticleDOI
TL;DR: An efficient procedure for the design of finite-length impulse response filters with linear phase is presented, which obtains the optimum Chebyshev approximation on separate intervals corresponding to passbands and/or stopbands.
Abstract: An efficient procedure for the design of finite-length impulse response filters with linear phase is presented. The algorithm obtains the optimum Chebyshev approximation on separate intervals corresponding to passbands and/or stopbands, and is capable of designing very long filters. This approach allows the exact specification of arbitrary band-edge frequencies as opposed to previous algorithms which could not directly control pass- and stopband locations and could only obtain (N - 1)/2 different band-edge locations for a length N low-pass filter, for fixed \delta_{1} and \delta_{2} . As an aid in practical application of the algorithm, several graphs are included to show relations among the parameters of filter length, transition width, band-edge frequencies, passband ripple, and stopband attenuation.

772 citations

Proceedings ArticleDOI
James D. Johnston1
09 Apr 1980
TL;DR: This paper discusses a family of filters that have been designed for Quadrature Mirror Filter (QMF) Banks that provide a significant improvement over conventional optimal equiripple and window designs when used in QMF banks.
Abstract: This paper discusses a family of filters that have been designed for Quadrature Mirror Filter (QMF) Banks. These filters provide a significant improvement over conventional optimal equiripple and window designs when used in QMF banks. The performance criterion for these filters differ from those usually used for filter design in a way which makes the usual filter design techniques difficult to apply. Two filters are actually designed simultaneously, with constraints on the stop band rejection, transition band width, and pass and transition band performance of the QMF filter structure made from those filters. Unlike most filter design problems, the behavior of the transition band is constrained, which places unusual requirements on the design algorithm. The requirement that the overall passband behavior of the QMF bank be constrained (which is a function of the passband and stop band behavior of the filter) also places very unusual requirements on the filter design. The filters were designed using a Hooke and Jeaves optimization routine with a Hanning window prototype. Theoretical results suggest that exactly flat frequency designs cannot be created for filter lengths greater than 2, however, using the discussed procedure, one can obtain QMF banks with as little as ±.0015dB ripple in their frequency response. Due to the nature of QMF filter applications, a small set of filters can be derived which will fit most applications.

722 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20223
2021281
2020375
2019436
2018420
2017392