The square patch loaded with two U-slot antenna is designed for WLAN and Wi-max applications. The slot antenna concept has been used in patch antenna designed to maximize the return loss and reduce antenna size. The dielectric of substrate is 4.4 that is FR4 substrate. The radiation pattern, directivity, return loss, VSWR and Bandwidth of the proposed antenna are calculated by using the HFSS.14 software package. Satellite technology is developing fast, and the applications for satellite technology are increasing all the time. Not only can satellites be used for radio communications and many more applications. The rectangular patch loaded with U-slot antenna is designed for WLAN and Wi-max applications. The slot antenna concept has been used in patch antenna designed to maximize the return loss and reduce antenna size. The dielectric of substrate is 4.4 that is FR4 substrate. The return loss, Bandwidth of the proposed antenna are calculated by using the Matlab software. In this paper, characteristic mode analysis (CMA) of three empirical design techniques for the probe-fed, symmetrically located, U-slot microstrip patch antenna, on a single-layer grounded substrate, is presented with supporting experimental data. The first method, resonant frequency (ResF), utilizes the existence of the four distinct ResFs, while the second one, dimensional invariance (DI), relies on the property of DI, forthe design of the U-slot microstrip patch. In both these methods, the optimization of the probe location is necessary for further enhancement of the 10-dB return loss bandwidth. The third method, dimensionally invariant ResF, that optimally combines the features of the previous two is developed here and shown toyield better bandwidth performance with minimal or no probe location optimization, and hence is superior to the other two for rapid prototyping. CMA is carried out for critical parameters, such as substrate electrical thickness, slot width, probe radius, and feed location variations, to assess their dominant influence on the characteristics of the U-slot microstrip patch antenna.