摘要:

A new general matrix theory of mode warping is advanced for directional couplers with nearestneighbour interaction and an arbitrary number of lines. The design procedure involves defining the form of the normal-mode vector, the type of ‘taper parameter’ and then computing changes in the elements of the ‘wave-propagation’ matrix due to differential changes of normal-mode vector. The wave-propagation matrices may thus be obtained at any point of the warped-mode coupler. These computed wave-propagation matrices at certain positions of the coupler are then used for obtaining the theoretical power against frequency plots at the output ports as well as for computing the physical dimensions of the coupler. A specific design using five coupled lines with the centre frequency at C band has been fabricated to demonstrate the power of the technique. Here using coupled comb/herringbone lines on microstrip, a normal mode of a single-line input is warped into a five-line mode with equal power splitting. Computed and measured results are presented for an experimental five-line coupler fabricated in open microstrip line form for working within 1.5 to 8.5 GHz. Applications and implications of the theory are discussed.

DOI:10.1049/ip-h-2.1986.0013

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The equivalent circuit parameters of rectangular waveguide H-plane junctions, bends and obstacles may be found by a two-dimensional finite element method. Results are presented for perfectly conducting and dielectric obstacles, and for a waveguide bend. Good agreement is obtained with previously published results.

DOI:10.1049/ip-h-2.1986.0014

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The matched symmetric five-port is synthesised directly from its scattering matrix using the equation relating the admittance and scattering matrices. The significance of the overall phase of the scattering matrix in this procedure is discussed and two alternative five-ports illustrate this. The design technique may be used to design other junctions from a given scattering matrix, provided a suitable geometry can be chosen.

DOI:10.1049/ip-h-2.1986.0015

出版商:IEE    

年代:1986

数据来源: IET

摘要:

An automatic computer controlled technique is proposed to measure the resonant frequency, loaded quality factor and coupling factor of a dielectric resonator coupled to a microstrip line. The complex transmission coefficient of the system is measured, as a function of frequency, by means of a network analyzer. At each frequency, the reflection coefficient is calculated and its magnitude is processed to obtain the characteristic parameters of the resonator. Estimated errors for Q- and coupling factors are in the order of 1% and for the resonance frequency are about 1 part in 106.

DOI:10.1049/ip-h-2.1986.0016

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A computer-aided design is introduced for E-plane filters with single and double metal inserts within a reduced-width or increased-width waveguide section, respectively. This design achieves filter performances with high peak attenuation in a broad second stopband. The theory described includes both the higher-order mode interaction of all discontinuities and the finite thickness of the inserts. The step-wall discontinuity effect is included in the optimisation process as an additional parameter to be optimised. Ka-band (26.5–40 GHz) design examples demonstrate the good stopband attenuation behaviour of this type of filters. Moreover, this design only requires thin strips, which are very appropriate for technical realisation.

DOI:10.1049/ip-h-2.1986.0017

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The performance of antenna systems is always influenced by diffraction effects. Diffraction problems may be analysed using physical optics or geometrical theory of diffraction. Here, the Fresnel field of a rectangular aperture with serrated edges is analysed using physical optics. The method can be applied very succesfully in compact antenna test range design for a fast prediction of the test-zone field performance.

DOI:10.1049/ip-h-2.1986.0018

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A simple moment solution is given for the problem of electromagnetic scattering from multiple conducting and lossy dielectric cylinders of arbitrary cross-section. The conductors may be of the form of strips and the dielectrics may be in the form of shells. The system is assumed to be excited by a plane wave polarised transverse magnetic to the axis of the cylinders. The equivalence principle is used to replace the conductors by surface electric currents and the dielectrics by equivalent surface electric and magnetic currents. Three coupled integral equations are obtained by using the condition on the tangential component of the electric field produced by these surface currents. The method of moment is used to solve the integral equations. A point matching technique is used with pulse expansion functions. Sample numerical results such as the induced currents on the conductors, the total near field, the scattered far field and the radar cross-section are presented. The agreement with available published data is excellent.

DOI:10.1049/ip-h-2.1986.0019

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The formulation of design equations for shaped dielectric lenses is considered under the assumptions of geometrical optics. The use of complex co-ordinates to track the refracted-ray directions introduces a very flexible approach in which no symmetry assumptions are necessary. The problem of designing a lens to serve as an optical transformer for aperture distribution control is shown, in general, to require the solution of a Monge- Ampere equation.

DOI:10.1049/ip-h-2.1986.0020

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The application of the log-periodic technique to the series-fed electromagnetically coupled overlaidpatch array allows antennas with flat conformal characteristics and wide bandwidths to be obtained. Ak-βanalysis of this and other microstrip array types indicate that the microstrip patch is not an optimum element for log-periodic arrays and that direct connection will result in arrays having a limited bandwidth. The addition of series capacitance to the patch equivalent circuit, implemented by electromagnetic coupling, allows an optimum to be approached. Log-periodic overlaid patch array design and measured results for an array with a 4:1 bandwidth are presented. These, together with a transmission-line analysis, indicate the array-design trade offs available and that the ultimate bandwidth is limited primarily by changes in the input return loss and radiation pattern due to the use of uniform thickness substrates.

DOI:10.1049/ip-h-2.1986.0021

出版商:IEE    

年代:1986

数据来源: IET

摘要:

In many applications, particularly on aircraft, the integration of two or more antennas into the same physical area is desirable. A technique, using compensated grating structures, is described which offers the opportunity of constructing radiating elements and feeds which are ‘invisible’ at a second frequency. This technique is described in detail and its application to microstrip and other similar media is discussed. Particular attention is given to the edges of the structures, and measured results clearly showing the ‘invisibility’ are presented. An array of ‘invisible’ microstrip radiators has been mounted in an existing primary aperture. Primary radiation patterns are given, which show the very small degradation introduced by the secondary array.

DOI:10.1049/ip-h-2.1986.0022

出版商:IEE    

年代:1986

数据来源: IET