摘要:

A generalised scattering matrix (GSM) of the generalised 2-port discontinuity is proposed for use in the analysis of multiportmultidiscontinuity structures. This gives the GSM of the discontinuity in a simple way and with a number of algebraic manipulations independent of the number of discontinuity ports. Moreover, they can be cascaded with the same procedure as two-port discontinuities. This leads to a simplification in the analysis of structures with multiple discontinuities and with more than 2 ports. An application to short-circuited E-plane septum and E-plane reaction cavities is considered. The results show that these structures can be used to obtain waveguide stop-band filters of small size and low cost.

DOI:10.1049/ip-h-2.1988.0001

出版商:IEE    

年代:1988

数据来源: IET

摘要:

A combined method, using the finiteelement approach and the analytical approach, is described for the solution of arbitrarily shaped discontinuities in a dielectric slab waveguide. Both TE and TM mode incidences are treated. The method is based on replacing the unbounded configuration by a corresponding bounded structure. The validity of the method is confirmed by comparing numerical results for step discontinuities with other available results. Computed results are also presented for typical boundary deformations in optical fibres caused by a fusion splice.

DOI:10.1049/ip-h-2.1988.0002

出版商:IEE    

年代:1988

数据来源: IET

摘要:

A matched waveguide five-port with partial symmetry is described. The linearSmatrix element/S-matrix eigenvalue relations for this device are derived. Six-port calibration curves are given for a practical realisation inX-band used in a six-port measurement system.

DOI:10.1049/ip-h-2.1988.0003

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Studies have shown that for a symmetrical five-port junction to be used in a six-port reflectometer set-up, it should ideally be matched over the operating bandwidth. Using the results obtained from an electromagnetic model, a suitable symmetrical five-port E-plane waveguide junction (with five attached H-plane tapers) was designed. The junction-with-tapers prototype when tested yielded a residual mismatch of less than 0.18 over the entire waveguide bandwidth.

DOI:10.1049/ip-h-2.1988.0004

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The paper determines the eigenvalues and conditions of propagation of hybrid modes inside a circular cylindrical waveguide with an impedance wall. The analysis allows for different longitudinal and transverse impedances on the walls. A general characteristic equation is derived from which the corresponding characteristic equations for circular cylindrical waveguides with a perfectly conducting wall, a corrugated wall or a dielectric lined wall can be obtained. Finally, it is found that the propagation of hybrid modes in circular waveguides with large radii is independent of the surface impedance.

DOI:10.1049/ip-h-2.1988.0005

出版商:IEE    

年代:1988

数据来源: IET

摘要:

In the paper, a new, efficient, modified three dimensional spectral domain solution is achieved for generalised planar periodic waveguides, in which a ‘modal spectrum’ is set up with respect to periodic loaded stubs. Slow-wave propagation characteristics on structures such as finlines and slotlines are investigated. Important behaviour, such as passband and stopband, related to cutoff and resonant frequencies is discussed in detail. The computed results are found to have good agreement with the measured ones.

DOI:10.1049/ip-h-2.1988.0006

出版商:IEE    

年代:1988

数据来源: IET

摘要:

A spherical modal matching technique is developed to analyse and design wide flare angle corrugated conical horns. The theory is verified by experimental measurements. It is found that the junction at the throat of the horn controls the return loss and the higher order mode excitation. The optimum throat geometry depends on the flare angle. For narrow flare angle horns, the first slot should be half a wavelength deep. For horns with semi-flare angles between about 20 degrees and 40 degrees, a short smooth wall conical section gives lowest return loss. For horns of larger flare angle the slot depth should be constant.

DOI:10.1049/ip-h-2.1988.0007

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Diffraction effects which arise in the direct far field geometrical optics synthesis of shaped beam reflector antennas are examined. A spherical wave expansion technique is introduced which allows the optical coverage area and reflector dimensions to be specified in Westcott's complex co-ordinate synthesis technique. Examples are given of the method when applied to the synthesis of typical beam shapes encountered in satellite communications.

DOI:10.1049/ip-h-2.1988.0008

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The paper describes the synthesis of shaped-beam dual-reflector antenna patterns using two methods. In the first, for a prescribed far field the antenna aperture field is obtained initially and then a Geometric Optics synthesis method used to define the reflector coordinates. In the second method an optimisation procedure is employed to shape the reflectors directly, so as to generate, through Physical Optics, the desired far field. The two methods are compared for the pattern corresponding to the EUTELSAT 2 spacecraft. Close agreement is found and differences ascribed to initial constraints.

DOI:10.1049/ip-h-2.1988.0009

出版商:IEE    

年代:1988

数据来源: IET

摘要:

A feeding technique for double-sided printed dipoles enabling the realisation of flat arrays on foam-like substrates with bandwidths up to 25% is presented. An experimental comparison with thin single-layer microstrip arrays shows that the available gains are equal, while the bandwidths for the double-sided dipole are much larger. A modification of microstrip analysis, presented in this work, provides useful design data for the double-sided elements.

DOI:10.1049/ip-h-2.1988.0010

出版商:IEE    

年代:1988

数据来源: IET