Showing papers on "Stopband published in 1984"

Quadrature mirror filter design in the time domain

Abstract: A new technique for designing quadrature mirror filters is described. The formulation, carried out in the time domain, is shown to result in an optimization problem requiring minimization of a quartic multinomial. An iterative solution is suggested which involves (computation of) the eigenvector of a matrix with a dimensionality equal to one half the number of filter taps. Our experiments show that convergence to the optimum tap weights is stable, and the accuracy of the final solution is limited only by the accuracy of the eigenvalue-eigenvector routine. As in an earlier technique, the user can specify the stop: band frequency the relative weights of the passband ripple energy and the stopband residual energy, and, of course, the number of filter taps.

E-Plane Integrated Circuit Filters with Improved Stopband Attenuation (Short Papers)

Abstract: Improved stopband attenuation is achieved by thick strips, by reduced waveguide sidewall dimensions, and by double planar integrated circuits. In contrast to thick strips which may cause high passband insertion losses and filters with reduced waveguide dimensions which require additional tapers, double planar E-plane integrated circuit filters combine the advantages of low costs, high stopband, and low passband insertion losses. Computer-aided design of a four-resonator Ka -band double metal insert filter achieves a calculated stopband attenuation between 40 and 60 GHz of more than 50 dB, the calculated minimum passband insertion loss is 0.43 dB (measured 1.8 dB). Higher order mode excitation and finite thicknesses of the inserts are included in the calculations.

Optical demultiplexer utilizing an Ebert mounting silicon grating

Abstract: A two-dimensional optical demultiplexer utilizing an Ebert mounting grating is proposed and discussed. In this demultiplexer, the optical system design to reduce aberration is very important. It is shown that aberration can be greatly reduced by modifying the input/ output facet. The experimentally fabricated demultiplexer has 2.0- 2.6-dB branching loss, >20-dB stopband rejection, and sharp cutoff branching characteristics.

An Investigation of Striplines and Fin Lines with Periodic Stubs

Abstract: In this paper, a technique based on the network-analytical formalism of electromagnetic fields is used to analyze the strip and fin lines with periodic stubs. Numercal results for the dispersion characteristics of the periodically loaded lines are presented. The effect of the loading stubs on the passband and stopband characteristics is investigated.

Evanescent mode triple ridge lowpass harmonic filter

Abstract: A waveguide lowpass filter has successive groups of three separate ridges spaced longitudinally in said filter. A center ridge of each filter has a larger cross-sectional area than two side ridges which are the same size. All ridges are parallel to one another in a longitudinal direction. The groups are associated with shunt capacitances and the spaces between adjacent groups are associated with series inductances in an evanescent mode. In operation, the filter is capable of supporting a TE10 mode in the passband and three modes, TE10, TE20 and TE30 in the stopband. The filter has a relatively high power handling capability as compared to previous evanescent mode lowpass harmonic filters.

Dielectric Waveguide Grating Design for Bandstop and Bandpass Filter Applications

Abstract: Techniques have been obtained for the precision design of dielectric waveguide (DW) bandstop filters in the form of a grating in DW which utilizes notches of varying depth. The grating is designed from a transmission-line prototype which has a prescribed stop band and also prescribed Chebyshev pass bands. Two such grating structures used with loads on one end and a 3-dB coupler can be used to form a bandpass filter.

Frequency selective side absorber for a meander line

Abstract: A meander line slow wave structure mounted on ceramic bars for a microwave device such as an injected beam crossed-field amplifier includes frequency selective attenuator means which will preferentially attenuate waves at frequencies near and within the stopband of the slow wave structure by the placement of side absorber bars of attenuating material adjacent to the outer side surfaces of a plurality of meander line finger segments. The frequency selective absorber material, in its preferred form, comprises a beryllia and silicon carbide ceramic composition which additionally adapted to accommodate metallic absorber top plates, nichrome films, and slotted side ring configurations.

Digital-to-analog converter device for processing PCM signals of different sampling frequencies

Abstract: A digital-to-analog converter device for PCM signals at different sampling frequencies comprises a signal converter which expands the frequency distance between a PCM signal band and a side band by converting the sampling frequencies associated with the PCM signals to be reproduced into higher frequencies. With this signal converter, a single low-pass filter can be simplified, having a gradual ramp cut-off characteristic for removal of the side band wherein a pass band cut-off frequency and a stop band cut-off frequency can be adapted for low pass filtering of the PCM signals at different sampling frequencies.

New Types of SAW Reflector and Resonator with Alternative (Positive and Negative) Reflection Coefficients

Abstract: Conventional SAW reflectors and resonators utilize only the negative or positive reflectivity. So, a large reflection coefficient per one wavelength cannot be obtained because of the large mode conversion into the bulk waves. This paper describes a new types of reflector with both of positive and negative reflectivity within a half or one wavelength. The positive and negative reflection can be obtained by combining the open metal strip and short metal strip which have 180'phase difference. Also, other types of the loading alternative reflection can be obtained by using mechanical loading effects. These reflectors havethe advantages of a large reflectivity, wide stopband, and the small mode conversion into the bulk waves. Experimental results on metal strip gratings show that the new reflectors provide very efficient reflection'characteristics. Also, experimental 100 MHz small size resonators on si02/128O YX LiNbO3 layered substrate show appreciably small capacitance ratio (Y=30) and a zero first-order temperature coefficient of frequency.

FIR low-pass filter design using parametric filter technique

Abstract: This paper describes a new design method for finite impulse response (FIR) filters. FIR low-pass filters which have quasi-equiripple characteristics in the stopband and arbitrary ones in the passband are designed. Applying the parametric filter design technique, the stopband zeros are given in the closed form. Hence, only passband zeros are iteratively approximated to shape passband characteristics. This method can be applied for both the minimum and the linear phase cases.

Digital-to-analog converter device

Abstract: A digital-to-analog converter device for PCM signals at different sampling frequencies (f s1 , f s2 . f s3 ) comprises a signal converter (6a) which expands the frequency distance between a PCM signal band and a side band by converting the sampling frequencies associated with the PCM signals to be reproduced into higher fequencies (2f s1 , 2f s2 ; f s3 ') ' With this signal converter, a single low-pass filter (4a) can be simplfied, having a gradual ramp cut-off characteristic for removal of the side band wherein a pass band cut-off frequency and a stop band cut-off frequency can be adapted for low pass filtering of the PCM signals at different sampling frequencies.

Caractéristiques de dispersion et impédances shunt de trois structures bipériodiques accélératrices en bande S

Abstract: Experimental results about three biperiodic standing wave accelerating structures are presented. Dispersion curves are given and an experimental method to eliminate the stopband is put forward. The effective shunt impedance and the transit time factor are measured by the perturbation method. Measured structure parameters are compared with SUPERFISH theoretical calculations.

A new class of very low sensitivity cascade-form digital-filters based on "passive" second order single-input single-output building blocks

Abstract: A new type of cascade form structure for digital filtering is proposed, with each building block being a second order section, that satisfies certain passivity properties. This passivity is essentially a "structure-induced" boundedness on the transfer function magnitude, and leads to low passband sensitivity. In addition, the cascade nature ensures low stopband sensitivity, as zeros on the unit circle continue to remain on the unit circle in spite of the quantization. The structure itself is independent of the pole locations and therefore meets a wide range of filtering applications.

Integrated VIS SC filter with lattice reference structure

Abstract: Symmetric VIS SC filters simulating reference filters in classical lattice configuration can be realised with less hardware. A fifth-order PCM lowpass with only three operational amplifiers has been designed and integrated in standard CMOS Si-gate technology. VIS SC lattice filters show excellent passband-sensitivity properties. Owing to the higher stopband sensitivity with respect to element tolerances, stopband attenuation requirements in excess of about 35–40 dB can be satisfied only by cascading lower-order SC lattice filters.