A new design of a slot-loaded rectangular microstrip antenna for single-feed dual-frequency operation is proposed and experimentally studied. The slots loaded in the patch are a pair of bent slots centered in the patch and oriented along the resonant direction, with the spacing between the two slots being about half the patch's radiating-edge length. By varying the bent angle and horizontal-section length of the slots, the frequency ratio between the two operating frequencies is tunable in a range from about 1.28 to 1.79. The two frequencies are also of the same polarization planes and similar broadside radiation patterns. (C) 2000 John Wiley & Sons, Inc.