Based on the cavity model analysis and the integral equation method, the structure was simulated with CST microwave studio and Ansoft HFSS, a ring patch polarized omni directional antenna has been designed with the coaxial line feed. The gain is greater than 12 dB at the central frequency of 1.575 GHz with more than 50 MHz bandwidth and lower 6 dB of axial ratio is reached, the gain of more than 10 dB is obtained at 3 GHz and the gain of greater than 10 dB at 4.6 GHz is obtained. After optimized and improved design, the better results have been achieved. The three dimensions of single layer by FR4 substrate material is smaller than 40 mm×40 mm×2 mm. The results of the two simulation software agreed well with each other and a fabricated sample was tested, it is remarkable for the similar planar antenna.