Time-Domain Simulation Technique For Antenna Transient Radiation, Reception And Scattering
This paper gives an insight on some features of transient electromagnetic events related to antenna and scattering problems involving the classical aspects of transient electrodynamics and engineering issues. Such properties like near-field range effects, peculiarities of transient antenna in radiation, reception and scattering modes and others, which are not considered enough in literature, will be treated here. Reaching this goal rigorous and asymptotic analytical bounds for linear and wire-grid modeled antennas will be introduced.
There are a variety of intuitively evident definitions here like pulse, ultra-wide band (UWB). transient, non-sinusoidal, non-stationary electrodynamics. Generally those phenomena can be treated from the point of view of energy beams (Zialkowski. 1992) as well as with its time history (Smith. 1997) or time-harmonic presentation. However inherent distortion of signal waveform is principal moment for electromagnetic pulse (EMP) simulators. high-resolution radars. spread-spectruni communications, electromagnetic compatibility (EMC) issue. VLSI and printed board design and so on. Generally each element of such system effects on signal waveform passing through it (Harmuth. 1990). Resulted signal is not rather simple replica of input waveform like in case of narrow-band or sinusoidal signal. Due to these reasons time-domain (TD) modeling of transient electromagnetic events is more preferable than frequency-domain (FD) techniques despite their mathematical equivalence due to the Fourier transform.
Traditionally numerical approaches to the transient electromagnetic problems are applied like FD method of moments with the next Fourier transformation or FDTD (Taflove. 1995). Also Baiun (1965. 1971) developed analytical approaches with the Laplace transform for some asymptotic cases. Generally numeric studies, mostly applied, have principal drawback followed from sufficient programming and computing efforts. Finally the physical meaning of the most numerical solutions is not initially evident. Therefore we developed simple mathematical models, which enable numerical simulations with universal mathematical software like Maple. Mathcad. Matlab etc. The result of such simulations will illustrate the major points of our study.