摘要:

AbstractThis article presents a study of the ARTMAP neural network in designing cascaded gratings. A neural network can be trained to keep changing the dimensions of the metallic strips, their distance of separation, their width, the number of layers required in a multilayer structure, and the angle of wave incidence until the frequency response of the structure matches the desired one. In the past, the back‐propagation (back‐prop) learning algorithm was used in conjunction with an inversion algorithm for the design of frequency‐selective surfaces. Unfortunately, both the back‐prop algorithm and the inversion procedure are slow to converge. In this work the Fuzzy ARTMAP neural network is utilized. The fuzzy ARTMAP is faster to train than the back‐prop, and it does not require an inversion algorithm. Several results (frequency responses) from cascaded gratings for various angles of wave incidence, layer separation, width strips, and interstrip separation are presented and discussed. © 1995 John Wiley

ISSN:0895-2477    

DOI:10.1002/mop.4650080402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractScan impedance of elements, especially near the edge of a finite array, differs from that of an element in an infinite array. A numerical experiment shows the standing‐wave behavior of scan impedance over the finite array, for a range of scan angles. The standing wave exists even for a broadside beam. © 1995 John Wiley&Sons. I

ISSN:0895-2477    

DOI:10.1002/mop.4650080403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractDoppler Lidar is a good candidate for wind velocity measurement. But the total Doppler shift experienced by the backscattered laser pulses with a conical scanning instrument varies in a wide frequency range. Narrowing intermediate frequency bandwidth could provide better performances for both detection and low noise amplification. Therefore, optical mixing and parametric amplification in the same device have been investigated with HgCdTe photodetectors cooled at liquid nitrogen temperature. The optical and microwave setup needed for simulating Doppler and testing these detectors is described. Some experimental results, which demonstrate the feasibility of this new heterodyning process, are given. © 1995 John Wiley&Sons. Inc

ISSN:0895-2477    

DOI:10.1002/mop.4650080404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractA new method, referred to as ISOMOM, is presented for reducing storage and execution time of standard moment‐method solutions. ISOMOM isolates the dominant elements of the moment‐method matrix using a smooth filter function on the integral equation kernel, and this leads to sparse matrix systems with about 20% or less nonzero elements. The method is applied to the metallic strip electric field integral equation for illustrative purposes. © 1995 John Wiley&Sons.

ISSN:0895-2477    

DOI:10.1002/mop.4650080405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractPerturbation methods are employed to determine the small‐signal behavior of an LC‐ladder nonlinear, lossless transmission line. It is shown that a straightforward, regular perturbation analysis results in nonuniformly valid expansions, which can be rendered uniformly valid by stretching the time variable. Perturbation methods are also used to show that, when dispersion effects are accounted for, solitons may propagate along the nonlinear, lossless transmission line. The dispersion characteristics of some equivalent circuits derived from a lossless transmission line are also analyzed. © 1995 John Wiley&Sons.

ISSN:0895-2477    

DOI:10.1002/mop.4650080406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article presents an analysis of a microstrip‐line‐fed radiating slot on a cylindrical surface. The reciprocity theorem is applied in this analysis, and the Green's functions for the structure studied here are derived and used in the moment‐method calculation for obtaining the slot impedance, which can be viewed as an equivalent series impedance at the slot position as seen by the microstrip line. Numerical results of the slot impedance for various cylinder radii are calculated, and the curvature effects on the slot impedance are discussed. The radiation pattern of the radiating slot is also calculated and presented. © 1995 John Wiley&Son

ISSN:0895-2477    

DOI:10.1002/mop.4650080407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThree‐dimensional numerical simulation of the complete structure and experimental measurements of a microstrip dielectric‐resonator bandpass filter (MDR‐BPF) are presented. The numerical simulation was performed by using the 3D finite‐element method (FEM). A bandpass filter using two dielectric resonators (DRs) in a rectangular metallic enclosure coupled through microstrip lines has been realized around 6.55 GHz. Numerical results and measured data are compared. Good agreements are achieved. The change percentage of the filter passband frequency as a function of the DR dielectric constant were investigated. © 1995 John Wiley&S

ISSN:0895-2477    

DOI:10.1002/mop.4650080408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAn original analysis, facilitated by the use of Chernoff bound techniques, is presented for an optically preamplified satellite PPM system employing a receiver that integrates over a time slot and compares the result with a fixed threshold. At 155‐Mbit/s operation we demonstrate a potential receiver sensitivity of 50.7 photons/bit with background noise present. We also compare results with those obtainable from a Gaussian approximation, finding the Gaussian approximation consistently less conservative for the cases considered. © 1995 John Wiley&Sons. I

ISSN:0895-2477    

DOI:10.1002/mop.4650080409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractAdequately modeling the radiation pattern of a high‐performance antenna system usually requires the expensive development of complicated electromagnetic software or the storage of an extremely large number of measured data. An alternative and efficient simulation technique is described in this article using a spherical wave expansion model, which requires the storage of a relatively small number of coefficients to define the function for the antenna's radiation pattern. © 1995 John Wiley&Sons. I

ISSN:0895-2477    

DOI:10.1002/mop.4650080410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe dispersion characteristics of open, asymmetrical planar structures may be obtained through the iterative solution of an eigenvalue equation in the spectral domain. During each iteration, a number of terms need to be calculated by means of numerical integration over an infinite range. In this article techniques for the treatment of slow‐converging integrals are described. © 1995 John Wiley&Sons. I

ISSN:0895-2477    

DOI:10.1002/mop.4650080411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY