Resonant frequency characteristics of air gap tuned circular microstrip antenna with uniaxially anisotropic substrate and superstrate layers is analysed in Hankel Transform domain using recursive equivalent circuit modelling. The effects of uniaxial anisotropy on the resonant frequency are investigated as the function of anisotropy ratio values of substrate and superstrate materials. According to the results, resonant frequency of anisotropic antenna exhibits incremental or decremental shifts with respect to isotropic one due to adjustment of the layer anisotropies and the thickness of the air gap. Thus, it is important to properly adjust layer anisotropies of the circular disk microstrip antenna for its efficient operation in microwave and communication systems applications. © 2010 J. of Electromagn. Waves and Appl All rights reserved.