Evolutionary development of a dual-band, dual-polarization, low-profile printed circuit antenna

This paper follows the evolutionary development of a low-profile dual-band, dual-polarization printed circuit antenna element. In an early development, a single-feed single-band circular-polarization printed-circuit perturbed slot element fed with a low-loss stripline was used for a low-cost array. In a second development, a shorted annular ring element operating at a low frequency is modified by filling the inner ring with a conducting cylinder in the form of a waveguide that operates at a higher frequency, thus creating a dual-band element. The two concepts are combined in the third development. The outside perimeter of a square annular ring is notched (perturbed) to produce a single-fed circular polarization at a low frequency band. The ring can be fed separately at two orthogonal points to produce two orthogonal circular polarizations. The area inside the shorting cylinder is used to house a notched square slot element fed with two independent orthogonal striplines and produces two orthogonal circular polarizations at a higher frequency band.