Abstract:
A low profile coplanar waveguide (CPW) fed printed
slot antenna is presented with uni-directional radiation properties.
The slot antenna radiates above a closely spaced artificial magnetic
conducting (AMC) reflector consisting of an array of rectangular
patches, a substrate and an electric ground plane. The electromagnetic
bandgap (EBG) performance of the cavity structure between
the upper conducting surface in which the slot is etched, and the
ground plane at the bottom of the reflector, is investigated using an
equivalent waveguide feed in the place of a half-wavelength section
of the slot antenna. From the reflection coefficient of the equivalent
waveguide feed one can determine the frequency band where minimum
energy will be lost due to unwanted radiation from the cavity
sides. The dimensions of the cavity were found to be very important
for minimum energy loss. Experimental results for the final antenna
design (with a size of 1.02λо X 0.82λо X 0.063λо ), mounted
on a 1.5λо X 1.5λо back plate, exhibit a 5% impedance bandwidth,
maximum gain in excess of 10 dBi, low cross-polarization,
and a front-to-back ratio of approximately 25 dB. This low-profile
antenna with relatively high gain could be a good candidate for a
2.4 GHz WLAN application.
