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have presented, the current through the load is 2 / Z [ E: -EZ+ 1.However, in this case we can also represent the current as E / ( Z( t ) ) where E is the voltage across the load and Z( t ) is the time varying impedance. (Only R is varying with time.)we now have a relationship that gives us an exact solution for f ( E:): where 2d 7 'c Now, let us look at the circuit used in the example. Using standard circuit techniques for determining the impedance yields R / j o C R + l / j o C z( I ) = j w L + Since (d/dt>e/*l = jwelor we can replace each occurrence of j w with d/dt. After this substitution, algebraic rearrangement of (6) and (7) yields (8), which is identical to (3) when all Relative FreqLiency Relotivp FI + x i~i~i i r -y Received 12-4-89 Microwave and Optical Technology Letters, 3/3, 98-102 ABSTRACT A method is proposed for using urruy element positions plur the element excitutions in order to ohtuin both acceptable sum and diflerence patterns for a monopulse array with u two-section feed network. Preliminary resuhs ure discussed.

Perfectly matched layers (PML's), which are employed for mesh truncation in the finite-difference time-domain (FDTD) or in finite element methods (FEM's), can be realized by artificial anisotropic materials with properly chosen permittivity and permeability tensors. The tensor constitutive parameters must satisfy the Kramers-Kronig relationships, so that the law of causality holds. These relations are used to relate the real and imaginary parts of the constitutive parameters of the PML media to deduce the asymptotic behaviors of these parameters at low and high frequencies.

In this paper, we introduce a novel approach for an efficient solution of matrix equations arising in the method of moments (MoM) formulation of electromagnetic scattering problems. This approach is based on the characteristic basis functions (CBFs), which are used to substantially reduce the matrix size because these bases are not bound by the conventional λ/20 domain discretization. As a result, it is possible to electrically solve large problems with much fewer unknowns than those needed when using conventional RWG basis functions. The accuracy and efficiency of the CBFs are demonstrated in a variety of scattering problems to illustrate the versatility of the approach. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 95–100, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10685

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