A new patch antenna is analysed which provides dual-frequency operation by means of two narrow slots close to the patch radiating edges. The two modes of operations show similar radiating properties. The ratio between the two frequencies can be well controlled within a range varying from 1.6 to 2, by using simple semi-empirical formulas derived from a physical model and tested by using a fullwave analysis. To obtain a more extended range of this frequency ratio, two tuning microstrip stubs are introduced on a back substrate. Satisfactory performances of simultaneous matching when using a single feed point is demonstrated. Several measurements are shown for both the input impedance and the radiation pattern.