Investigation results on circularly polarised microstrip antenna arrays at 2.45 GHz are presented. Effects of the feed network in the sequentially rotated technique to improve the antenna performance are reported. A new serial feed sequentially rotated to construct coplanar-fed arrays of large size, that improves antenna performance, is proposed. The results achieved show that this technique not only leads to an improvement in bandwidth, but also results in a better radiation pattern with lower sidelobe levels in the E and H radiation planes. A new 2×2 antenna subarray that has been arranged using the serial-feed sequentially rotated technique was fabricated. The measurement results for resonant frequency, return loss, axial ratio, bandwidth and radiation pattern confirm the integrity of the simulation results.