摘要:

The problem of electromagnetic coupling through slots in a conducting plane is studied using characteristic-mode theory; i.e. the problem is formulated as an operator equation whose solution determines the characteristic modes of the problem. The cases treated are those when the plane is excited by either a transverse electric (TE) or a transverse magnetic (TM) plane waves with different angles of incidence. It is assumed that the media to the right and to the left of the plane exhibit different electromagnetic properties. Where comparison is possible, there is a good agreement with classical results. The computer program is described briefly, and representative examples are given.

DOI:10.1049/ip-h-2.1993.0069

出版商:IEE    

年代:1993

数据来源: IET

摘要:

The complex shunt STUB-G circuits met in the practice of three-port circulators may be matched using one eight-wave long alternate lines or quarter wave long impedance transformers. Another possibility is to employ halfwave long UEs at the characteristic planes of the junction where the complex gyrator circuit is a series STUB-R network. Although this topology is not particularly compact the impedance levels met in this solution are appropriate for the matching of junction circulators with highQcomplex gyrator loads. This paper gives the synthesis of this problem in the case of a single halfwave long UE.

DOI:10.1049/ip-h-2.1993.0070

出版商:IEE    

年代:1993

数据来源: IET

摘要:

A microwave filter synthesis procedure for almost arbitrary phase and amplitude responses is described. Although based on a passive transversal filter implementation, it contains an efficient numerical algorithm to allow for losses in the delay line and multiple reflections between taps; this permits large amounts of energy to be drawn from the delay line so that the filter can have reasonably low loss. The performance of chirp filters and a phase shifter implemented in copper stripline and microstrip are presented as a demonstration. A fractional bandwidth of 150% has been achieved for the chirp; this is about double that produced by previous design methods. It is intended that eventual implementations will include superconducting linear phase filters, chirp devices and amplitude or phase equalisers.

DOI:10.1049/ip-h-2.1993.0071

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Dual-frequency microstrip antennas are expected to find applications in mobile satellite communications. The authors present a multiplayer microstrip structure with a radiating disc. Theoretical results are compared with experiment. Input impedance and mutual coupling between the two feeds are discussed.

DOI:10.1049/ip-h-2.1993.0072

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Progress is described in the theoretical modelling, design and testing of overmoded circular TE01mode waveguide applicable to high power, low loss transmission in the microwave and lower millimetre wave bands. Theoretical techniques, originally developed to model low loss millimetre band waveguide for commercial telecommunications, have been adapted to overmoded sheathed-helix waveguide (with continuous unwanted-mode suppression) subject to new constraints of tighter bend radius relative to the wavelength, high power and significantly less overmoding. Numerical design analysis using coupled mode theory has yielded helix waveguide designs which have been experimentally verified.

DOI:10.1049/ip-h-2.1993.0073

出版商:IEE    

年代:1993

数据来源: IET

摘要:

It is shown that the application of linear and nonlinear algorithms improves the convergence of the series representing the doubly infinite free-space periodic Green's function. The numerical results indicate that the algorithms converge faster than the first-order acceleration. Convergence properties of the Green's function series are reported for the ‘on plane’ case in which the seriesjias the slowest convergence. The number of terms taken in the series and a relative error measure are given for various values of a convergence factor as the observation point is taken different locations within a unit cell.

DOI:10.1049/ip-h-2.1993.0074

出版商:IEE    

年代:1993

数据来源: IET

摘要:

A fast algorithm is presented to solve for the scattered field of a two-dimensional, dielectric-coated conducting cylinder using a hybrid of a combined field surface integral equation and volume integral equation. The fast algorithm is an extension of the fast multipole method and it relies on the translation of scattering centers to speed up the matrix-vector multiplication in the conjugate gradient method. The scatterer is first divided into many subscatterers. Instead of directly computing the matrix-vector multiplication, which needsN2multiplications, an efficient approach is used to reduce the floatingpoint operation count required. The algorithm has a computational complexity ofO(N1.5).

DOI:10.1049/ip-h-2.1993.0075

出版商:IEE    

年代:1993

数据来源: IET

摘要:

Absorption and dispersion spectra of the most important and millimetre-wave active atmospheric gases for arbitrary atmospheric paths are calculated. The atmospheric propagation model (APM) adopts a line by line summation technique to characterise the resultant resonant absorption and dispersion spectra of various trace constituents such as O3, N2O, CO, NO, NO2, SO2, ClO, HNO3, NH3and major contributors H2O and O2. The model assumes a spherically layered atmosphere with each layer taken to be in local thermodynamic equilibrium and with exponential profiles of density and pressure between layer boundaries. The relative air mass integral and the line shape function are also appropriately evaluated.

DOI:10.1049/ip-h-2.1993.0076

出版商:IEE    

年代:1993

数据来源: IET

摘要:

In the paper, a fast source tracking algorithm for an arbitrary two-dimensional power inversion adaptive array is presented and investigated. By solving two sets of linear equations to calculate the preprocessing needed, the algorithm tracks the environment through adaptively adjusting the array response zeros directly in a time-multiplexed manner to minimise the output power. The main advantages of the algorithm are that it has good tracking behaviour and the zero or source positions are directly available.

DOI:10.1049/ip-h-2.1993.0077

出版商:IEE    

年代:1993

数据来源: IET

摘要:

A detailed analysis of the capacitance of a subharmonic millimetre-wave mixer diode presented. The individual components contributing to the total capacitance are identified, with values derived for each component for a 183 GHz Schottky design. A new method is described to determine the shunt capacitance associated with the complicated geometry of the metal bonding pads for planar diodes. It is shown that this component can contribute up to 12 fF towards an overall device capacitance of 25 fF for the 183 GHz design. The inclusion of air bridging and back-etching techniques is shown to reduce this value by 70%, resulting in a lower capacitance, higher cutoff-frequency subharmonic diode device.

DOI:10.1049/ip-h-2.1993.0078

出版商:IEE    

年代:1993

数据来源: IET