D. Sanchezhernandez et Id. Robertson, ANALYSIS AND DESIGN OF A DUAL-BAND CIRCULARLY-POLARIZED MICROSTRIP PATCH ANTENNA, IEEE transactions on antennas and propagation, 43(2), 1995, pp. 201-205
In the last decade a great effort has been made concerning research on
frequency agility of microstrip patch antennas. In all these attempts
an increase in length or height of the patch is generally expected an
d there is a tradeoff between wider bandwidth and good axial ratio. Th
is paper presents the analysis and design of a novel dual-band circula
rly polarized microstrip patch antenna using a spur-line band-stop fil
ter and a perturbation segment technique. This dual frequency operatio
n can be obtained without increasing either the size or the thickness
of the patch while other features are not degraded.