A wideband electromagnetic-coupled single-layer microstrip patch antenna is
studied experimentally. With dielectric and foam substrates of total thick
ness similar to 0.13 lambda(0), a rectangular patch antenna with impedance
bandwidth (SWR less than or equal to 2) of 49% and 3dB gain bandwidth of 54
% are obtained. It has an average gain of 6.5dBi and stable radiation patte
rns across the passband. Furthermore, with the employment of a stacked para
sitic patch, a 58% impedance and gain bandwidth is achieved with similar ra
diation patterns and a higher average gain. A notable structure in the feed
ing design is that an inverted L-shaped strip is connected to the end of th
e microstrip line and no matching network is required.