Analysis Of The Antennas' Coupling And The Biological Effects Of Electromagnetic Fields By FDTD Method

As one of the most important antennas which radiate ultra-wide band (UWB)electromagnetic pulse, the transverse electromagnetic (TEM) horn antenna has beenwidely applied in many areas because of its several advantages, such as broad bandfrequency spectrum, constant impedance, good directivity, small size, simple design, etc.In this paper, The TEM horn antenna is composed of two isosceles triangular metallicplates that have a certain angle, and it is fed by the coaxial line through a parallel platetransmission line. A thin-wire FDTD algorithm is adopted in this thesis to simulate thecore wire of the coaxial line, and a simple feed model of the coaxial line is presented toanalyze the coupling of the electromagnetic fields with the voltage and current at thejunction of the coaxial line and parallel plate transmission line. This paper analyses thecoupling of the two-element TEM horn arrays, presents the energy distributions innear-field region, and numerically calculates the self-impedance and mutual-impedanceof each element of antenna array.The TEM horn antenna modeled by the conventional FDTD method will presentserration on its surface. This may produce the surface wave in the process of radiationand reduce the calculative precision. In this paper, we put forward a modified conformalfinite-difference time-domain (MCFDTD) algorithm and adopt it to amend theconformal gridding on internal surfaces of the TEM horn antenna. The radiationcharacteristics of a single TEM horn antenna in near-field region are also analyzed inthis thesis.With the development of science and technology, human is surrounded byelectromagnetic fields coming from broadcasting, mobile communications, and so on.This has resulted in public concern about the health hazards of the electromagneticabsorption in the human body (especially in the head). Therefore, it is very significantto study the biological effects of electromagnetic fields by numerical algorithm. Thispaper finished modeling a realistic human head, and the specific absorption rate (SAR)distributions in a head exposed to plane wave have been calculated by the FDTDmethod.