Showing papers on "Stopband published in 1975"
TL;DR: In this paper, a surface acoustic wave band-elimination filter was developed employing s.a.w. resonators composed of interdigital transducers with a large number of electrodes, exhibiting more than 80 dB stopband rejection with a passband attenuation of less than 1 dB.
Abstract: A surface-acoustic-wave (s.a.w.) band-elimination filter has been developed employing s.a.w. resonators composed of interdigital transducers with a large number of electrodes, exhibiting more than 80 dB stopband rejection with a passband attenuation of less than 1 dB.
10 citations
TL;DR: In this paper, prototype characteristics of nonequiripple antimetric elliptic-function filters which can be realized in orthogonal cascaded dual-mode circular or square waveguide structures are presented.
Abstract: Selected prototype characteristics of nonequiripple antimetric elliptic-function filters which can be realized in orthogonal cascaded dual-mode circular or square waveguide structures are presented. Cavity-coupling data for 4-, 6-, and S-section 0.01- and 0.05-dB-ripple passband designs with variable stopband levels are tabulated. Quantitative comparisons of elliptic and Chebyshev filter designs are also discussed, indicating the superior characteristics of elliptic networks.
8 citations
01 Apr 1975
TL;DR: In this article, the use of the numerical phasedifference filter in the single-sideband modulation scheme for frequency-division multiplexing is investigated and compared with the Weaver-modulator scheme proposed by Freeny et al.
Abstract: The use of the numerical phase-difference filter in the single-sideband modulation scheme for frequency-division multiplexing is investigated and compared with the Weaver-modulator scheme proposed by Freeny et al. A simple algebraic solution to the approximation problem for arbitrary specifications in the stopband is given. The sensitivity of the stopband attenuation is the main problem that precludes the use of RC active structures; it is shown that the digital version can be implemented with a reasonable coefficients wordlength. The structure of the filter is optimised for round-off noise performance. Finally, the two modulation schemes are compared.
8 citations
TL;DR: The approximation of attenuation curve for a recursive digital filter is solved for arbitrary specifications in the stop-band and in the pass-band using the classical theory of the transformed plane and linear programming.
Abstract: The approximation of attenuation curve for a recursive digital filter is solved for arbitrary specifications in the stop-band and in the pass-band. The problem is split into two parts; the first one uses the classical theory of the transformed plane and the second one works with linear programming. The method is illustrated by some specific examples.
5 citations
TL;DR: In this article, a characteristic function is derived by maximising the mean-square error in the stopband of lowpass filters with no finite zeros and a monotonic magnitude response.
Abstract: Lowpass filters with no finite zeros and a monotonic magnitude response are discussed. A characteristic function is derived by maximising the mean-square error in the stopband. Analytically, it has been proved that H filters are the most selective of all other filters with monotonic magnitude response.
3 citations
TL;DR: In this article, an exact method is presented to find a new class of parametrical polynomials which provides (n - m) zero derivatives of relative delay at p = 0 and m zero derivatives about p = \infty.
Abstract: An exact method is presented to find a new class of parametrical polynomials which provides (n - m) zero derivatives of relative delay at p = 0 and m zero derivatives about p = \infty . Explicit expressions of the polynomials for n = 2,3,4,5 , and 6 (and for 0 \leq m \leq n ) are derived from a linear second-order differential equation. Among the possible applications of these polynomials we show their interest in equalizing a class of microwave filters and for design of multiplexing systems.
2 citations
01 Oct 1975
TL;DR: In this paper, the design of an 11 GHz channel branching filter with couplings between non-adjacent resonators is presented, and the conctruction of a 6-section filter is presented.
Abstract: The design of an 11 GHz channel branching filter which has to meet high stopband attenuation requirements demonstrates that elliptic-function filters are superior to conventional filter types as regards insertion loss and size. The conctruction of a 6-section filter with couplings between non-adjacent resonators is presented. Some design rules are derived.
TL;DR: In this paper, a new apodisation of electrodes which provides surface-acoustic-wave filters capable of operation without apodization loss and with sufficiently large stopband attenuation was reported.
Abstract: The letter reports a new apodisation of electrodes which provides surface-acoustic-wave filters capable of operation without apodisation loss and with sufficiently large stopband attenuation. The effectiveness of the apodisation was shown by experiments.
12 May 1975
TL;DR: In this paper, the authors extend the results to multi-section inhomogeneous coupled-line filters with large mode-velocity ratios, and present experimental and theoretical data for these filters.
Abstract: Design data for single-section inhomogeneous coupled-line filters based on large even/odd mode-velocity ratios has recently been published. The purpose of this paper is to extend those results to multi-section inhomogeneous coupled-line filters with large mode-velocity ratios. Both experimental and theoretical data are presented. The rather complex pole-zero structure of single-section inhomogeneous coupled-line filters permits great flexibility in designing multi-section filters. Very sharp transitions between pass- and stop-bands are possible as well as large stopband to passband width ratios.