Showing papers on "Stopband published in 1969"

Sharp-cutoff low-pass filters using floating gyrators

Abstract: The practical realization in gyrator-C form of a seventh-order Cauer-parameter low-pass filter with 40-dB stopband attenuation is described. The three floating coils of the equivalent LC filter were replaced by capacitor-loaded semi-floating gyrators. The gyrators were realized in hybrid form using thick-film resistors. The performance of the filter over a temperature range from -40/spl deg/ to +61/spl deg/C was very satisfactory, without any attempt at temperature compensation being made. This, together with the wider allowable element tolerances (compared with other active RC filter methods) shows the inherent suitability of gyrator-C filters for integration. Also in this paper some of the special problems and characteristics of gyrator-C filters are theoretically discussed, in particular the realization of gyrators with floating ports, gyrator Q-enhancement, and component tolerances in gyrator-C filters.

Ferromagnetic Resonance in Ba4Zn2Fe36O60 (ZnU) and Mn‐Substituted ZnU Single Crystals

Abstract: Resonance experiments were performed on Ba4Zn2Fe36O60 (ZnU) and Mn‐substituted ZnU single crystal spheres using a reflection technique and transverse pumping. The influence of surface polish on linewidth was studied from 26.5–40 GHz at 300°K. In general, ΔH was found to be only slightly dependent upon frequency. The lowest linewidth was 18.5 Oe measured on a Mn‐substituted ZnU sample at 26.5 GHz. 4πMs, HA, ΔH, and γeff values are presented at 4.2°, 77°, and 300°K. A bandpass filter was constructed using a spherical resonator in an orthogonal configuration. The electrical characteristics are as follows: (1) Passband insertion loss, La=3.1–5.4 dB; (2) 3 dB bandwidth =200–380 MHz; (3) Stopband attenuation =30 dB, except spurious modes which are greater than 10 dB below main resonance.

Polylithic crystal bandpass filter having attenuation pole frequencies in the lower stopband

Abstract: A bandpass crystal filter of the type which uses coupled resonators and has a shunt capacitor at the junction between pairs of coupled resonators exhibits a stopband loss-frequency characteristic which is approximately symmetrical and monotonic In some applications, it is necessary to sharpen up at least one side of the filter and this extra loss could be obtained if one or more frequencies of infinite loss could be added in the adjacent stopband By connecting the parallel combination of a capacitor and a two-terminal quartz resonator across the junction between pairs of coupled resonators, the loss-frequency characteristic may be modified to include frequencies of infinite loss in the lower stopband

Interference Emission Filtering in High Power Microwave Transmitters

Abstract: Requirements of U. S. Department of Defense and other agencies are that system designers control the spectral characteristics of all new transmitters. The purpose of this paper is to consider the noise outputs of all commonly used microwave tubes and from there proceed to survey the methods of removal and elimination of noise by filtering. Practical design tradeoffs comparing desired stopband attenuation levels versus sacrifice in system VSWR, passband insertion loss, power handling, cost, and size are made. Some recent advances in high power microwave filtering are introduced with recommendations of filter chains usable with various tubes and under various conditions.

Disk-wire mechanical filter using bridging wire to achieve attenuation pole

Abstract: A general stopband disc-wire type mechanical filter having at least four circle mode vibration-type discs therein with a first coupling wire means connected to the perimeters of all four discs and a second coupling wire means connected only to the first and the fourth disc and bridging the two discs therebetween. The second bridging coupling wire means has a length such that it produces a 180* phase shift of energy transferred therethrough with in the passband. Circle mode-type discs resonate in phase with each other at the lower end of the passband and out of phase (with the adjacent discs) at the upper end of the passband. Consequently, the energy transfer through the bridging coupling wires is out of phase with the energy transfer through the first coupling wire means both at the lower and upper ends of the passband, thereby producing the general stopband characteristic.

Quasi-Optical Low-Pass Filters which Attenuate by Absorption

Abstract: A type of filter structure is discussed which has application for quasi-optical systems using focused beams or oversized waveguide. The filter structure consists of a number of focusing reflectors which in the passband of the filter focus the energy from one reflector to the next so that the energy is beamed in a zig-zag fashion. However, the focusing reflectors are made from arrays of spaced-apart metal plates with the edges of the plates parallel to the E field. The focusing face of each reflector is thus formed by the front edges of the plates, When the frequency is suffcientIy high so that the spacing between the plates is greater than a half-wavelength, the energy passes between the plates and is absorbed by dissipative material placed therein. Thus above a certain frequency the reflectors are absorptive and a stopband is formed. A trial three-reflector structure was fabricated and tested with very encouraging results. The minimum loss points in the passband were about 1 dB, and the stopband was broad and free from spurious responses. There were 3- or 4-dB attenuation spikes in the passband due to "trapped modes," but it should be possible to eliminate these by improved mode launchers.