The basic geometry of the U-slot patch antenna is shown in
Fig. 1. This antenna was introduced in 1995 by Huynh and
Lee [1] as a single-layer, single-patch patch linearly polarized
antenna with an impedance bandwidth exceeding 30% for an
air substrate of about 0.08λo thickness. Since then, this design
has been extensively studied [2]-[7], not only for wideband
applications but also for dual-band and triple-band
applications, as well as for circular polarization operations
[8]-[9]. The purpose of this paper is to present results showing
the versatility of the U-slot patch antenna, although only
simulation results are given in this paper for brevity.