AbstractTwo simple single layer single feed cross slot patch antennas with air dielectric (εr = 1) substrate providing multiple frequency operation is proposed.At first a cross slot rectangular patch antenna providing quad frequency operation is proposed and experimentally studied. The measured quad frequencies are 1.93, 2.57, 3.18, and 3.56 GHz. Another cross slot trapezium patch antenna providing quad frequency operation is proposed and experimentally studied. The measured quad frequencies are at 1.43, 1.81, 2.97, and 3.58 GHz. Trapezium patch antenna is found to be more compact in size and as well as reduction in resonant frequency compared to rectangular patch antenna. Measured values are in good agreement with simulated results. The measured radiation patterns at each measured resonant frequency are also shown. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:612–615, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25765