By using a meandered rectangular patch and a slot-coupling feed, compact dual-frequency operation of microstrip antennas is achieved. In this design, the two operating frequencies are mainly controlled by the patch dimensions and the insetting slit length; a large frequency ratio (> 2.5) of the two operating frequencies can also be obtained. For fixed dual-frequency operation, an antenna size reduction as large as ~ 50% has also been obtained using the present proposed design as compared to the case using a regular rectangular patch.