摘要:

Two ferrite-limiter configurations, block and slab, are separately investigated experimentally, and are then combined to give an X-band limited with a 15 W peak threshold power and a maximum limited power of 50 kW (corresponding to a dynaic range of 35 dB) when measured with a 0–75μs1 kHz p.r.f. pulse (duty cycle 0–0075).

DOI:10.1049/ij-moa.1978.0007

出版商:IEE    

年代:1978

数据来源: IET

摘要:

The excitation of optical fibres by a focused laser beam is described and the particular modes excited are identified. The results are used to reanalyse an experiment on baseband frequency measurement. Misconceptions in the original analysis concerning the role of the source are pointed out.

DOI:10.1049/ij-moa.1978.0008

出版商:IEE    

年代:1978

数据来源: IET

摘要:

The difficulty of realising effective couplers for single-mode fibres imposes a significant obstacle to their application. The paper is concerned with the use of a holographic element, which substantially reduces the sensitivity to tolerance errors in the manufacture of such a coupler. The approach is based on the use of a hologram output window for the cable end, the coupling between the two windows proceeding by means of pseudoplane waves. The effect is to transfer the need for precision to the factory, the coupler to be assembled in the field being relatively undemanding. The system is applicable to bundles of fibres; preliminary experimental results for the coupling between one pair of fibres to another pair are described.

DOI:10.1049/ij-moa.1978.0009

出版商:IEE    

年代:1978

数据来源: IET

摘要:

A method is described for calculating the frequency-dependent properties of symmetrical microstrip Y-junctions and 120° bends. The Y-junction includes angles of 120° and may have two different line impedances. Using a waveguide model with frequency dependent parameters, a field-matching technique proposed by Kuhn is employed to compute the scattering matrix of a Y-junction with three equal line impedances. The generalised telegraphist's equations are used to extend the calculations to Y-junctions with two different line impedances. The transmission properties of 120° bends are derived from the Y-junction by a symmetry consideration. The theoretical results are compared with measurements, and theory and experiment are found to correspond closely.

DOI:10.1049/ij-moa.1978.0010

出版商:IEE    

年代:1978

数据来源: IET

摘要:

The paper describes a method of determining overlap lengths for interdigital electrodes of an s.a.w. filter by use of constrained damped least squares. In this method, some constraints which must be met exactly by a designed filter, as well as the effects of electrical terminations, can be simultaneously taken into account. The method was applied to the design of a practical filter for a Japanese television receiver. The filter designed was compared with that designed by a conventional Fourier analysis.

DOI:10.1049/ij-moa.1978.0011

出版商:IEE    

年代:1978

数据来源: IET