Circularly Polarized Sparse Arrays Realized by Randomly Rotated Linearly Polarized Antennas

High-quality circular polarization is obtained using a novel concept that uses a sparse random distribution of randomly rotated linearly polarized antennas. Key benefit of this concept is that a very narrow circularly polarized beam is obtained with a limited number of antenna elements. Another advantage is a significant reduction of the generated heat-flux density as compared to dense regular array concepts. Both the sidelobe level and cross-polarization level can be controlled over a very wide frequency band and behave as 1/N for large array sizes, where N represents the number of array elements. A dual-frequency 16 element demonstrator was realized to show the versatility of our concept. Measured circularly polarized radiation patterns for scanning in the D-plane at 3.8 and 5.8 GHz are in good agreement with the predicted patterns.