A dual-mode, dual-band 2.4/ 5.2 GHz circular microstrip patch antenna for airborne application is presented. Initially, a reference circular patch antenna is designed on Rogers© 5880 substrate for dual-mode (TM11 and TM01) performance with a single feed location. The bandwidth (BW) of the reference antenna is found to be 33 MHz and 155 MHz at 2.4 GHz and 5.2 GHz bands respectively. Later, the BW of the reference antenna at both the frequency band is enhanced with the help of proximity patches placed around the periphery of the reference/driven patch. It is found that the BW of the antenna at both the bands is enhanced by 2.5% at 2.4 GHz and 3.9 % at the 5.2 GHz band and similar improvements in their gains are also observed. The proposed antenna is fabricated and tested in an anechoic chamber for its impedance bandwidth and radiation pattern performance. A close match in simulated and measured performance of the antenna is achieved and an appropriate comparison of measured quantities is well illustrated in the paper.