Fibre-optic delay-line devices for r.f. signal processing

A bandpass filter and a discriminator for r.f. signals have been constructed by using fibre-optic delay lines, and their frequency-response characteristics have been investigated. Both devices had a fundamental frequency of 193 MHz, and the filter had a 3 dB passband of 10 MHz.     

Minimising signal distortion in f.l.f. active filters

A simple method is described which minimises signal distortion in follow-the-leader-feedback (f.l.f.) active filters. The procedure, which is easily implemented on a digital computer, determines the free design parameters of f.l.f. structures such that the signal-level capabilities of the filters are maximised.     

Q dependence of IMPATT-diode f.m. noise

Measurement of IMPATT-diode-oscillator f.m. noise, for external Q factors ranging between 100 and 10 000, showed that the product of r.m.s. frequency deviation and square root of power output is inversely proportional to the Q factor, in accordance with the Edson formula for f.m. oscillator noise. The excess-noise temperature, varying between 30 and 50dB, rapidly increases with current through the diode. The correlation for f.m. and a.m. noise lies between 0.8 and 1.     

Joint-loss dependence on mismatch parameters in graded-index optical fibres

The dependence of the mean value and the RMS joint-loss distribution on geometrical and optical parameters deduced in practical cases by simple and compact formulas. The different sensitivities of the various parameters can suggest different, more advantageous choices of the tolerance set.     

Two-dimensional variable f.i.r. bandpass filters

In this letter the cosine transformation is extended to the design of constant-centre-frequency/variable-bandwidth and constant-bandwidth/variable-centre-frequency circularly symmetric 2D f.i.r. bandpass digital filters.     

Moulded microwave squid for r.f.-attenuator calibration

The letter describes the use of a moulded microwave SQUID which has been used to calibrate a high-precision waveguide-beyond-cutoff (w.b.c.o.) r.f. attenuator with an accuracy of 0.0024 dB (s.d.).     

Form of Doppler processing for radars of random p.r.i. and r.f.

A self-validating procedure ls outlined for the noncoherent combination of phase information from multiple radar pulses of random r.f. and p.r.i., for the precise measurement of range rate. The method is contingent on `point target? and `point source? assumptions.     

Variable-cutoff two-dimensional lowpass f.i.r. digital filters

A recently formulated transformation for implementing 1-dimensional variable-cutoff filters is extended to the design of 2-dimensional variable-cutoff lowpass filters, and it is shown that the cutoff frequencies along the two frequency axes can be independently controlled, each by one parameter. The filters designed with the 1st-order transformation have certain drawbacks, which are shown to be overcome with the 2nd-order transformation with proper constraints on the variable parameters.     

2. Weltkonferenz für Photovoltaik in Wien

Ohne Zusammenfassung     

Annealing effects on transition temperature of r.f. sputtered Bi-Sr-Ca-Cu-O thin films

High-T_c Bi-Sr-Ca-Cu-O thin films have been made on YSZ substrates by single-target r.f. sputtering. The target was prepared for a composition of Bi₄Sr₃Ca₃Cu₄O_x. The best film showed the onset of superconductivity at 83 K and zero resistance at 75 K. The dependence of T_c(o) of sputtered films on annealing conditions is studied in detail.     

Umweltmanagement für Hochspannungsnetze

High voltage transmission lines are the subject of increasing public opposition. Environmental issues have become an important factor for utility companies, governments, standardisation organisations and local authorities. In this situation environmental management and more active public communication will have to play a significant role. The realisation of environmental management systems (EMS) for overhead power lines is discussed with regard to system boundaries and operation conditions. Based on standard EN ISO 14001 a model of an environmental management system manual for a high-voltage grid company is developed. Environmental information systems, environmental index values and the importance of EMS for rights-of-way management are discussed and solutions are proposed.     

Noise in IMPATT oscillator at large r.f. amplitudes

The noise-current generator of a large-signal IMPATT oscillator is shown to be inversely proportional to the avalanche starting current. This is verified by a numerical study of a large-signal model of an IMPATT oscillator.     

Intermodulation in an f.m. oscillator injection locked by an f.m. signal

Analysis of injection locking by f.m. signals is presented when the locked oscillator and the locking source are frequency modulated by the same signal. Intermodulation noise and optimum deviation of the locked oscillator are derived, assuming f.m. by band-limited Gaussion noise. Previous published results and recent experiments confirm the results obtained.     

Kundenabrechnungssystem für STEWEAG-Sondervertragskunden

The liberalization (de-regulation) of the energy markets creates a new environment, with new requirements and demands on utilities and their business practices. STEWEAG responded to these changes of the market by initiating in 1993 an indepth re-engineering process for the whole company. The customer account (billing) management system for industrial and commercial customers is to be regarded as part of this process of re-engineering. The variety of features of the system described in this presentation should enable the reader/audience to understand why STEWEAG has opted for this system.     

Admittance of a slot antenna following r.f. voltage breakdown

An experiment to determine the input admittance of a slot antenna after r.f. voltage breakdown outside the aperture has occurred is described. It is found that the conductance decreases and the susceptance increases with input-power level.     

Series operation of Gunn diodes for high r.f. power

Several GaAs Gunn diodes have been made to operate at a single frequency simultaneously in series operation. This, as explained, is an unexpected result and enables the impedance level of these semiconductor devices to be raised and the power level to be increased. This can have important consequences for ultrahigh-power generation.     

Thin stoichiometric silicon nitride prepared by r.f. reactive sputtering

Thin silicon nitride films were prepared on silicon wafers at deposition rates of 4 nm/min to 56 nm/min by r.f. reactive sputtering. Various mechanical, chemical and optical properties were investigated as a function of r.f. power, gas composition and temperature by means of AFM, RBS, XPS and an ellipsometer. Chemical stoichiometric films, with N-to-Si atomic ratio of 4:3 and refractive index of 2.0 were achieved even at room temperature. An interference filter for a UV detector with central wavelength of 254 nm was manufactured based on sputtered nitride, aluminum and silicon dioxide.