 3. optimal choice of the integration centre, which is boundaries of the structure may become very high. critical for the efficient application of this method. The contribution of many different propagating modes For this last case, seven different methods (starting with is evaluated, taking into account the losses (both di- the trivial solution) have been investigated. It was shown electric and conduction) with an equivalent reflection that the optimally fitted method (optimally means that coefficient. The constant component estimation the parabolic phase behaviour is fitted to osculate the real proved the most stable, better than the statistical spherical one as efficiently as possible, i.e. up to and method or the ESPRIT algorithm. The intuitively including second degree terms), gave excellent results expected behaviour is confirmed, namely that the with only four times the number of FLOating Point op- K-factor increases with increasing losses, and with erations per Second (FLOPS) of the trivial solution. Both decreasing size. Horizontal postion of scanner (m) Horizontal postion of scanner (m) (a) Measured results. (b) Simulated results. Figure 4.7-4 Phase of the reflected field of a 0.35 X 0.5 X 0.02 m Plexiglass plate at 5.8 GHz. Propagation modelling and channel characterisation CHAPTER 4.7 4.7.2.2 Differential equation methods that the proposed method was a better uniform absorber than Mur 2nd AbBC, which is another merit of the FDTD models proposed AbBC. Method to terminate the calculation space in FDTD Method to speed up the Frequency Dependent in a computationally efficient manner (FD) FDTD simulation which accommodates the The ideal truncation method has a low data storage re- frequency dependent media for UWB (Ultra Wide quirement, an easy construction procedure, high flexi- Band) systems by removing the Courant-Frie- bility, high stability and high accuracy. No current drichs-Lewy (CFL) stability condition truncation method satisfies all of these points. A method In recent years, the Alternating Dire