Numerical aspects in time domain modelling of arbitrarily curved thin wire antennas

Comparative Assessment of Power Absorption in Heads of Adults and Children Exposed to the Radiation of Cellular Phones at 1800 MHz

“…The geometrical details of the linear antenna are: wire thickness 2w = 2.5 mm, length λ/4 = 2.1875 mm and feeding gap d = 1.25 mm. The geometrical details of the examined helical antenna are: helix radius α = 2.5 mm, pitch B = 1.25 mm, wire thickness w = 0.1 mm, turns L = 4, and feeding gap d = 0.2 mm (Cerri et al, 1999). Either of the above described phone radiating elements is mounted on the top corner of a metal handset box as shown in Fig.…”

A hybrid method combining TLM and MoM method for efficient analysis of scattering problems

“…Equation (3) can be solved for the actual current values Ik,n in every time step using the marching on in time version of the MOM. In this way the equation (3) involving integral and differential operations is transformed into a linear, iterative relation that provides an explicit evaluation of the current [6]. At the actual time step the unknown current Ik,n is calculated by using the (4) where Gkm,i contains the coupling coefficient vectors of the current values [5] at earlier time steps i. Kk, is the self term integral (m = k).…”

“…We give numbers m to all boundary surface elements on the TLM-subregion. The radiated electromagnetic field on the center of these patches coming from the current distribution along the wire segments is obtained by [ (6) where Sk is the location of the wire segments. R is the distance between the destination rm on the boundary surface element m of the TLM-subregion and source position vectors r' on the wire segments, T = t -R/c is a properly delayed time.…”

“…R is the distance between the destination rm on the boundary surface element m of the TLM-subregion and source position vectors r' on the wire segments, T = t -R/c is a properly delayed time. By approximating the current to be constant at given time in a given subdomain we obtain the radiated e. m. field at the patch m by (6). destination and at the source points, respectively.…”

“…This implies that the unknown total field EBtot and HBt0t on the interface can be directly calculated from the known incident field and an integral that is also known from the past history of the same field. This process is called marching-on-in-time (MOT) method [6]. In every time step on the interface patch m, the e. m. field values coming from outside the TLM-subregion are obtained by superposition of the radiated field from the wire structure and the radiated field from the neighbored patches s. This field values E"ut and H r,out are mapped on the TLM wave amplitudes am,j, on those transmission lines which are cut by the TLM-subregion boundary, and injected back to the TLM simulation [8] am,j 1 (-nTm x nTm xEjut +ZnTm x HrOUt) (9)…”