The prototype of the proposed antenna in Fig. 2 was fabricated and
investigated experimentally. A photo of the proposed antenna prototype
is shown in Fig. 5. The antenna overall size is
, where is the dielectric wavelength
at 5.5 GHz. The Simulated and measured results of the proposed antenna
and a plain rectangular patch of same dimensions are
shown in Fig. 6. From the figure, the U-slot effect for broadening the
antenna bandwidth is obvious. The impedance bandwidth realized by
simulation and measured results are listed in Table II. According to the
measured results, the U-slot technique increases the impedance bandwidth
for more than two times. The difference between the simulated
and measured results is due to the defects in the prototype during fabrication.
A contour plot for the projected 3D radiation pattern of the proposed
antenna is generated with full wave simulation at 5.5 GHz and is shown
in Fig. 6, where two distinct directive beams are clearly seen. The maximum
radiation lies in the plane, whereas a null exists in the
plane.
To study the effect of the U-slot inclusion, as well as the variation of
the pattern along the frequencies of the entire bandwidth, the radiation
patterns at 5.3, 5.5, and 5.8 GHz in the yz plane is presented in Fig. 7.