High-Gain Dual-Band Dual-Sense Circularly Polarized Spiral Series-Fed Patch Antenna

This paper demonstrates a dual-band circularly polarized (CP) two-dimensional (2D) series-fed patch array antenna. The CP rotating sense in each band is opposite to each other, which makes them well-suited for the downlink and uplink in satellite applications. The antenna can be designed to achieve a very high gain with a simple feeding structure using spiral microsip line, which can be integrated on a single-layered substrate. A theoretical framework for this type of antennas has been developed, which facilitates an efficient and fast design procedure requiring minimal computational resource. A prototype has been fabricated and measured, showing operating bandwidths (overlapped 10-dB return loss, 3-dB gain, 3-dB axial ratio bandwidths) of about 7% and 5%, realized broadside gains of 21.5 and 22 dBic at 12 and 14 GHz bands, respectively. This is an outstanding performance considering that the antenna profile is only 0.03 free-space wavelength (at 12 GHz) and the ratio between two operating frequencies is very tight accounting to only 1.17.