are two resonant frequencies at 1.825 and 2.1 GHz, which
can also be seen in the Smith chart in Fig 7(b). The large
circle indicates that good matching is expected over a broad
band of frequencies.
The measured impedance bandwidth is shorn in Fig. 8.
A 26.5 % impedance bandwidth for return loss 5-4 dB has
been achieved over a frequency range from 1.605 to 2.095
GHz. This does not agree well with the simulated results that
return loss is less than -1OdB. The tests were made on a finite
ground plane, while an infinite ground plane was used in the
simulation. It is not certain that the inductance of the feed
probe has been properly included in the simulation.
Nevertheless, the experimental results confirm that this
method of introducing an additional radiating resonance is
feasible, and deserves tinher study and optimisation.