Single feed circularly polarised microstrip ring antenna and arrays

Single feed circularly polarized antennas are receiving much attention within the antenna community. Circular polarization is beneficial because current and future applications require the additional design freedom of not requiring alignment of the electric field vector at the receiving and transmitting locations. A single feed allows a reduction in the complexity, weight, and RF loss of an array feed. Circularly polarized strip antennas, CP-MSA, have the additional advantage of small size and produce a completely planar antenna which is compatible with microwave and millimeter, MIC, and monolithic, MMIC, integrated circuits. This paper introduces a simple and robust design of a single feed antenna system; namely a stub ring antenna fed by proximity coupling from an embedded microstrip line. We present an analysis of a single element and two and four element arrays.