Two different tri-band microstrip patch antenna designs are presented. Antennas are designed and simulated using the commercial simulation Sonnet Suites [(Sonnet Software, version: 12.56 www.sonnetsoftware.com (2009)] and simulated results are compared against measurements in detail. Target application of the first design is radar systems in IEEE 802.11, wireless communications in wireless local area network and worldwide interoperability for microwave access bands. The second tri-resonance antenna is designed to operate in the 9–13 GHz band and comparisons between simulations and measurements are presented. Results show three resonance frequencies at which design presented herein achieves return loss better than 30 dB with the maximum 10 dB return loss bandwidth of 4%. Resonance frequencies are 9.52, 10.66, and 12.60 GHz, which meets the design specification of covering the X-band. A detailed parametric study of the geometry, dielectric thickness, and dielectric constant is also provided. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.