Single feed proximity coupled circularly polarized microstrip monofilar archimedean spiral antenna array

The analysis is presented for a microstrip feed proximity coupled monofilar Archimedean spiral antenna four-element array. Interactions between the mi crostrip corporate feed and the radiating elements are rigorously included. Results demonstrate that circular polarization can be achieved with proper spiral arm length. Polarization of either sense is controlled by the locat ion of the feedline, The 3-dB axial ratio (AR) and 2 V standing wave ratio (VSWR) bandwidths are 9%. The antenna is small (2R/lambda(0) = 0.33) and th e interelement spacing is 0.51 lambda(0). The microstrip feed produces a co mpletely planar antenna system, which is compatible with microwave and mill imeter, microwave integrated circuit (MIC), monolithic, monolithic microwav e integrated circuit (MMIC), and integrated circuits.