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Abstract: A semi-analytical methodology is presented for the accurate analysis of time-domain radiation characteristics of antenna sensors. A locally conformal finite-difference time-domain technique is adopted to derive a minimal pole/residue spherical harmonic expansion of the equivalent currents excited on a suitable Huygens surface enclosing the sensing device. In this way, by using the singularity expansion method, the time-domain gain and effective height of the structure can be evaluated analytically, in terms of the newly introduced incomplete spherical Bessel functions, as the superposition of non-uniform spherical wave contributions attenuating along with the time and space according to the complex poles accounting for the natural resonant processes occurring in the device. The accuracy of the developed technique is assessed by application to an ultrawideband bow-tie antenna-based sensor for millimeter-wave radar measurements. [Copyright &y& Elsevier]

A compact wideband planar-printed antenna for wireless communications is presented. A suitable shape of the antenna arms and a proper tapering of the feeding line are employed to achieve an impedance bandwidth of more than 10 GHz useful to meet the requirements of several wireless communication standards. An enhanced locally conformal finite-difference time-domain (FDTD) numerical procedure, based on a suitable normalization of the electromagnetic field-related quantities together with a near-to-far-field transformation, is developed to perform the full-wave analysis of the radiating structure. The proposed numerical procedure allows the accurate evaluation of the electromagnetic field distribution from the FDTD domain up to the far-field region, achieving a reduced computational burden compared with conventional FDTD formulations. Using the proposed technique, the electromagnetic and circuital behaviour of the antenna is then derived and analyzed in detail. Numerical results concerning the antenna parameters are in good agreement with experimental measurements. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]