摘要:

This paper deals with the electromagnetic characterisation of the transmission and scattering properties of an aperture in a thick conducting plane filled with an inhomogeneous composite material for transverse magnetic (TM) polarisation. Of particular interest in this analysis is the introduction of a new technique that combines the finite element and boundary integral methods. The conjugate gradient method and fast Fourier transform are also incorporated for the solution of the resulting system to allow the treatment of large apertures. Numerical examples are presented which demonstrate the validity, versatility and capability of the technique.

DOI:10.1049/ip-h-2.1990.0030

出版商:IEE    

年代:1990

数据来源: IET

摘要:

This paper describes an analytical method capable of transforming the scattered data from a line source into a plane wave, in the case of circularly symmetric targets, without resorting to the computer intensive plane wave synthesis procedure. A tomography experiment is simulated as a potential application of this method.

DOI:10.1049/ip-h-2.1990.0031

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A study of multilayer microstrip antennas fed by coaxial probe or microstrip line is presented. The method developed is applicable to structures with stacked or offset radiating elements of various shapes including rectangles, discs and triangles. Theoretical and experimental results of input impedance are given for the different structures. Radiation information is presented and the relative merits of different structures are discussed.

DOI:10.1049/ip-h-2.1990.0032

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Measurements of the effect of a diffracting aperture on a Gaussian beam at 230 GHz {λ = 1.3 mm) are reported, and are in good agreement with theoretically calculated beam shapes. This is of importance in the design of compact diplexers. It is found that apertures ≥2.4 times the 8.7 dB beam size (1/efield size, w0) should be used to ensure beams unmodified due to truncation.

DOI:10.1049/ip-h-2.1990.0033

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The resonant behaviour of a novel microstrip rhombic resonator is investigated by analysing an equivalent circuit based on transmission line modelling. Design curves showing the dependence of resonator performance on its parameters, as well as the substrate parameters, are presented. Experiments carried out showed a significant reduction in insertion loss when the rhombic resonator is dielectrically shielded. The resonator could be used as a microwave bandpass filter or a stabilisation circuit for microwave oscillators in both hybrid and monolithic integrated circuits.

DOI:10.1049/ip-h-2.1990.0034

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The introduction of a step discontinuity in one of the arms of a symmetrically coupled microstrip rhombic resonator creates a disturbance in the symmetry of the resonator, and results in the splitting of the resonant frequency. This is evidence of the fact that two degenerate modes are excited in the resonator and experiments carried out verify this phenomenon. Design curves are also presented to show the dependence of resonator performance on its parameters, as well as substrate parameters. This resonator could find applications in double-tuned narrowband microwave filters.

DOI:10.1049/ip-h-2.1990.0035

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A novel technique for checking the accuracy of wideband electrical measurement data is presented, based on the Hilbert transform relationship between the real and imaginary parts of a complex function. Fundamental properties of the transform are summarised and the convergence of the numerical integration process considered and illustrated. Functions E1(ω) and E2(ω) are identified as possible indicators of the intrinsic errors in the data and various examples are given to examine the effects of curvefitting, sharp responses, statistically dependent and independent random errors, and mathematically generated data. It is concluded that with specialist interpretation the new technique can be a valuable checking tool in some wideband measurement programmes, particularly when the typical cost of the latter are considered.

DOI:10.1049/ip-h-2.1990.0036

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The analysis of an arbitrary angle H-plane waveguide bend is given in this paper using the boundary residual least square method. This method avoids the problem of calculation unsteadiness, which may be encountered by other methods such as the point-matching method or the method of lines. Numerical results obtained agree well with the experimental results in the literature. A series of useful equivalent circuit parameter curves are presented.

DOI:10.1049/ip-h-2.1990.0037

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A numerical method based on the coupling of the finite difference method in the time domain with the discrete Fourier transform, is presented and is applicable to axially symmetrical resonant systems. An appropriate treatment of the resultant Fourier coefficients provides the frequency spectrum and the spatial distribution of the modes defined in the structure. The validity of the method has been shown by applying it to systems of a known analytical solution: a homogeneous cavity and a cavity dielectrically loaded at its base.

DOI:10.1049/ip-h-2.1990.0038

出版商:IEE    

年代:1990

数据来源: IET