An analysis of annular, annular sector, and circular sector microstrip antennas

Results are presented from an analysis of three types of microstrip antenna elements: annular, annular sector, and circular sector. The method of analysis is the same as that used by Lo et al. (1979) and Richards et al. for the rectangular and the circular disk elements. Only the salient features of the method are discussed here. Tables setting forth the normalized resonant frequencies for a variety of differently shaped antennas are included. A comparison between the measured and calculated impedances shows that the resonant frequencies are predicted with reasonable accuracy from the table, a firm conclusion, however, is not posible because the actual dielectric constant of the antennas and its nominal value may not be the same. The impedances of antennas constructed of fiberglass-reinforced PTFE printed circuit board 1/16th of an inch thick with a nominal dielectric constant of 2.55 are computed and measured. The predicted and measured values are found to be in good agreement.