Stacked circular microstrip patch antenna with increased bandwidth

In order to obtain larger bandwidth a stacked circular
microstrip patch antenna has been investigated. A line
transformer has been applied to achieve input impedance matching
in a larger bandwidth. This configuration offers larger bandwidth
but still maintains planar shape, low profile of the antenna and
manufacturing simplicity. The stacked patch antenna showed very
good gain. The co-polar and cross-polar radiation patterns were
not significantly affected by the line transformer.