A new feed system is presented for improving the quality and bandwidth of circularly polarised stacked microstrip antennas (CPSMAs). The feed system consists of a microstrip line and a via (or pin) from the microstrip line to a driven patch. A systematic design process to achieve near-optimal CP performance from these antennas is presented. An example design demonstrated a measured 3dB axial-ratio (AR) bandwidth of 17 and a measured 10dB return bandwidth of 35. The measured gain is more than 8dBic over the 3dB AR bandwidth. The total height of the antenna is 8.536mm or 0.156λo at 5.5GHz. The new feed system is found to be very useful for the design of wideband, compact, low-cost, CP microstrip antennas and arrays.