Multi-bandpass Filter Research Articles

Design of Microwave Multibandpass Filters with Quasilumped Resonators

Design of RF and microwave filters has always been the challenging engineering field. Modern filter design techniques involve the use of the three-dimensional electromagnetic (3D EM) solvers for predicting filter behavior, yielding the most accurate filter characteristics. However, the 3D EM simulations are time consuming. In this paper, we propose electric-circuit models, instead of 3D EM models, suitable for design of RF and microwave filters with quasilumped coupled resonators. Using the diakoptic approach, the 3D filter structure is decomposed into domains that are modeled by electric networks. The coupling between these domains is modeled by capacitors and coupled inductors. Furthermore, we relate the circuit-element values to the physical dimensions of the 3D filter structure. We propose the filter design procedure that is based on the circuit models and fast circuit-level simulations, yielding the element values from which the physical dimensions can be obtained. The obtained dimensions should be slightly refined for achieving the desired filter characteristics. The mathematical problems encountered in the procedure are solved by numerical and symbolic computations. The procedure is exemplified by designing a triple-bandpass filter and validated by measurements on the fabricated filter. The simulation and experimental results are in good agreement.

Compact tunable multibandpass filters based on liquid-filled photonic crystal fibers

We demonstrated a compact tunable multibandpass filter with a short size of about 9 mm and a high wavelength-tuning sensitivity of up to -2.194 nm/°C by means of filling a liquid with a high refractive index of 1.700 into the air holes of a photonic crystal fiber (PCF). Such a PCF-based filter maintains an almost constant bandwidth and a large extinction ratio of more than 40 dB within the whole wavelength tuning range of more than 100 nm. Moreover, the transmission spectrum of the PCF-based filter is insensitive to the stretch force and the curvature of the fiber.

효과적인 잡음 제거와 가속도 계측을 통한 구조적 변위 추정 연구

In this study, the estimation method for the structural displacements by the acceleration measurement is investigated for effective real-time structural monitoring. Theoretically, the velocity and displacement data during the specific period can be obtained by integration of the measured acceleration. But, the integrated data is highly affected by unexpected error sources such as noise signal. So, the effective and rational method for the noise elimination or minimization should be suggested and used. In this study, an effective noise filtering method for an useful displacement estimation by double integration is suggested based on the characteristics of structural dynamics. For the rational noise filtering technique applied to the measured acceleration data, the multi bandpass filter, which allows the signals nearby the peak frequencies of measured data, is newly suggested. By the suggested filtering and double integration method, the estimation method of structural displacements using an acceleration measurement is suggested in this study. The accuracy and rationality of the suggested method was validated using the numerical example obtained by finite element analysis. In the validation, the displacement data estimated by the suggested method was directly compared with those obtained by highpass filter and bandpass filter, formerly well known methods.

Multiple Surface Plasmon Resonances in a Metal–Insulator–Metal Structure Assembled Via Silver–Copper Nanoparticle Arrays

The Ag–Cu nanoparticle arrays, prepared using the electrochemical deposition method, were assembled into the metal–insulator–metal (MIM) structure with polyvinyl alcohol acting as insulating layer, the transmission spectrum of the MIM structure was observed to support the multiple surface plasmon resonances in the wavelength range 1,000 to 2,600 nm. The multiple peaks were formed due to the superposition and coupling of the surface plasmon resonance of nanoparticles with various sizes in the metal layers. The newly found MIM structure in which multiple resonances exist has a potential application in multiband-pass filters and optical magnetic metamaterials at the resonance wavelength.

Diamond-Structured Photonic Crystals with Graded Air Spheres Radii.

A diamond-structured photonic crystal (PC) with graded air spheres radii was fabricated successfully by stereolithography (SL) and gel-casting process. The graded radii in photonic crystal were formed by uniting different radii in photonic crystals with a uniform radius together along the Г-Х <100> direction. The stop band was observed between 26.1 GHz and 34.3 GHz by reflection and transmission measurements in the direction. The result agreed well with the simulation attained by the Finite Integration Technique (FIT). The stop band width was 8.2 GHz and the resulting gap/midgap ratio was 27.2%, which became respectively 141.4% and 161.9% of the perfect PC. The results indicate that the stop band width of the diamond-structured PC can be expanded by graded air spheres radii along the Г-Х <100> direction, which is beneficial to develop a multi bandpass filter.

Design and Fabrication of Transmission line based Wideband band pass filter

A multi section wideb and band pass filter with a centre frequency of 2.3 GHz and 3-dB bandwidth of approximately 618 MHz, is designed and fabricated. The design of the filter is based on transmission line section based circuit configuration. The salient features of this filter isthat it provides low insertion loss, sharp rejection along with simple approach and easy realization. The designed filter is simulated using Agilent® ADS tool and the experimental characteristics are found to be in close agreement with the simulation.

Design of a new compact dual-mode multiband bandpass filter using multi-armed ring-open-loop resonators without coupling gaps

In this article, we proposed at first step a new compact dual-mode bandstop filter with broad stopband and low insertion loss in the passband using one ring resonator.Based of this microstrip ring resonator, a novel type of multibandpass filters is proposed. The idea of the proposed filters is to engineer the transmission band using multireject band resonators, which are implemented using multi-armed open-loop resonators that are directly coupled to the input/output ports. Each resonator pair of arms creates a reject band in the transmission response. By properly adjusting the multireject bands, appropriate multitransmission bands are created. The idea was verified by designing three different filters with multibandpass response. The designed and fabricated filters have compact size with good agreement between the measured and simulated responses. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2668–2672, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25576

Development of a HTS Slot Antenna With Multi-Bandpass Filters

We developed a single-chip receiver antenna combined with coplanar waveguide (CPW) impedance matching circuits and multi-bandpass filters (multiplex receiver). Firstly, we designed a HTS slot antenna with 10.5 GHz center frequency. Next, in order to compensate the reactance of the antenna at different center frequencies of the BPFs, we attached the reactance compensation transmission lines behind the -junctions. Finally, we design the channel #1 BPF and channel #2 BPF matched to the input impedance of the antenna and reactance compensation line. The channel #1 BPF has center and channel #2 BPF has center . The prototype YBCO 2-channel BPFs was fabricated and verified the design theory.

A FILTER DESIGN METHOD BASED ON COMBINATION WAVELETS

This paper presents a method to design a filter with combination wavelets. The combination wavelets filter (CWF) is formed by frequency shift and single wavelet superposition. This paper discusses how to select the parameters needed to construct the filters with Gaussian combination wavelets. The low-pass, high-pass, band-pass, band elimination and multiband-pass filters are designed and the examples given. The combination wavelets filter can be designed easily and conveniently by choosing the correct parameters. This method can be used flexibly and widely.

Evaluation of triple‐band filters for quantitative epifluorescence microscopy

The performance characteristics of two sets of triple-band epifluorescence filters have been evaluated for use with digitally enhanced fluorescence microscopy. Use of such filters, at most, requires movement of the excitation filter, while the dichroic and emission filters remain fixed, allowing multi-wavelength imaging to be performed on standard microscopes. The dyes appropriate for use with these particular filters include Texas Red (TR), Bodipy (BD), FITC and Cascade Blue (CB), four fluorophores now commonly conjugated to both immunochemical probes and other proteins and lipids of biological interest. Good spectral separation existed for most experimental conditions allowing accurate localization of the different fluorophores during multi-wavelength imaging. Anomalous responses were observed during near-UV excitation at high concentration for some dyes. Scanning spectrofluorometry demonstrated that concentration-dependent spectral shifts occurred, resulting in large increases in near-UV absorbance. Despite the complexity of concentration and dye-interaction effects, quantitative measurements of dye concentration could be made, even in regions of multiple dye co-localization. Therefore, multi-band pass filters are an additional valuable approach for performing quantitative fluorescence microscopic imaging.

CCD microscopy and image analysis of cells and chromosomes stained by fluorescence in situ hybridization

This paper reviews methods and applications of CCD microscopy for analysing cells and chromosomes subjected to fluorescence in situ hybridization (FISH). The current status of indirect and direct FISH staining methods with respect to probe labelling, detection sensitivity, multiplicity and DNA resolution is summarized. Microscope hardware, including special multi-band pass filters and CCD cameras required for FISH analysis, is described. Then follows a detailed discussion of current and emerging applications such as the automated enumeration of chromosomal abnormalities (counting of dots in interphase cells), comparative genomic hybridization, automated evaluation of radiation-induced chromosomal translocations, and high-resolution DNA mapping on highly extended chromatin. Finally, the limitations of the present methodology and future prospects are discussed.