Ultra-compact parametric modelling of three-dimensional antenna radiation pattern for impulse radio-ultra-wide band ray tracing

In ultra-wide band (UWB) propagation channel modelling, antenna effects - namely frequency and polarisation aspects - must be considered to provide realistic waveform characteristics and realistic signal received power. The authors propose an efficient method which enables ultra-compact parametric modelling of fully three-dimensional antenna radiation behaviour for UWB ray tracing channel simulation tools. Two complementary techniques based on a vector spherical harmonic (VSH) expansion of antenna radiation function are proposed as a solution for (i) compression of the amount of data needed for describing antenna characteristics and (ii) fast and reliable reconstruction of antenna array response for waves coming from arbitrary directions and with arbitrary frequency variations. The most significant VSH coefficients are first extracted and then compressed in the frequency domain. The method is evaluated through the study of an UWB monocone antenna. It is shown that data compression rates as high as 1:1719 are achievable in practice.