The invention disclosed in this document is a dual-band antenna element in which each band can simultaneously operate with two orthogonal senses of circular or linear polarization. The dual-band nature of this element stems from the presence of two separate radiating structures. The antenna engineer has flexibility over the dimensions selected for this element which, in turn, provides flexibility over the frequency ratio between the two bands. The low band radiating element is a shortened square ring antenna element utilizing a novel capacitive loading technique for size reduction; the high band radiator is a square ring slot element. This antenna element radiates dual-circular or dual-linear at each of the two operational frequency bands without the need for hybrid couplers or active components.
The element uses a printed circuit design that provides a low profile, light weight, and low cost design that makes it desirable for integration with laptop technology, wireless access points, space born radars, cellular phone handsets and bases stations, and many other areas of the ever growing field of wireless communications. The ability to integrate the dual-substrate capacitive loading technique for size reduction in this element makes the element suitable for integration into a dual-band array with uniform lattice spacing; this makes the element attractive to synthetic aperture radar and multifunction radar applications. To the inventors’ knowledge, an element of this kind has not been discussed in the literature, and this element marks a significant development in the field of antenna engineering.