Simulations were made using HPADS-2002 Vl.5
Momentum based on the mixed potential integral equation
(MPIE) formulation. According to the simulated results in
Fig. S(a). it is seen that two adjacent resonant modes are
excited, which leads to a wide bandwidth. They are centred
near 2GHz and 2.7 GHz. The impedance bandwidth,
determined from -1OdB return loss, is 0.950 GHz or about
40%, with respect to the centre frequency at 2.375 GHz. The
-10dB return loss band is from 1.9 GHz to 2.85 GHz which
fully covers the frequency spectrum of IMT-2000 from 1885
to 2200 MHr. Fig. 5(b) also illustrates the simulated
broadband impedance behaviour. It can be seen that one
small circle encloses the centre of the Smith chart. as
required for optimum bandwidth. The input impedance ofthe
proposed design was also measured using an HP8510C
nrtwork analyser. and the results are shown in Fig. 6(a) and
(b) respectively. The measured results have impedance
bandwidth of 23% (return loss 5-IOdB) with a centre
frequency 2.6 GHz and fully cover the frequency spectrum
from 2.3- 2.9 GHz. The simulated impedance bandwidth is
17% higher than the experimental results. and there is a slight
shitt in the centre frequency. This is probably due to the use
of a finite-size ground plane in the tests, instead of an infinite
ground plane as used in the simulations. With slight scaling
to adjust the centre frequency, the antenna is clearly easily
capable of covering the 1.885 to 2.2 GHz band far 3C
mobile.