This article presents a novel circularly polarized sequentially rotated slot antenna array (CPSSAA) designed to operate at a frequency of 5.5 GHz. This antenna is suitable for communication applications such as WLAN/WiMAX. Method of feeding is based on sequential rotation with seven quarter-wavelength transformers. In this case, the elements with 200 impedance could be replaced by other elements with different input impedance. Reducing the elements input impedance, maximum power can be transferred to the elements. Because the lower losses in transmission line occur in presence of lower impedance, the 3 dB axial-ratio bandwidth of the CPSSAA extends to approximate to 1.3 GHz. The CPSSAA was designed to operate over the frequency range between 4.5 and 6.4 GHz corresponding to an impedance bandwidth of 34.86% for VSWR<2. Acceptable agreement between the simulation and measured results validates the proposed design. (c) 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:358-363, 2015.