The simulated radiation patterns at 915 MHz are shown
in Fig. 10. In this figure, the normalized radiation patterns
are plotted in both x-z planes and y-z planes. It is seen that
the values of Eθ and Eφ are nearly equal near θ = °0
and180° , which verifies a CP radiation in the z axis. The
simulated gain and radiation efficiency is about -2.8 dB and
41% in the z direction at 915MHz. Note that the radiation
patterns would be better with a perfect matching network