Abstract: A dual circularly polarized broadband array antenna includes two arrays of spiral-like antenna elements. The arrays of spiral-like antenna elements are oppositely oriented and located on opposite sides of a substrate member. The spiral-like antenna elements have a loop portion with a free end, and a tail portion. The tail portion of adjacent antenna elements are connected to one another. The antenna elements have feed points, located at the free end, with the feed points of the first array being offset from the feed points of the second array. Each feed point is connected to a balun. The offset of the feed points is adjusted to achieve enhanced isolation between the signals from the two arrays. The antenna can have tuning elements adjacent to the substrate member.

Abstract: A multi-frequency radome includes a material-tuned radome portion for generating a low frequency passband of the radome and an integrated low pass frequency selective surface (FSS) portion for tuning a high frequency passband of the radome. The FSS portion provides a reactance necessary to move an upper passband of the material-tuned radome to a desired spectral location. Because the FSS portion is a low pass structure relative to the low frequency passband of the material-tuned radome portion, it does not substantially affect the low frequency passband when the FSS portion is applied to the material-tuned radome. In one embodiment, the FSS portion is designed to take advantage of various well known properties of FSS structures, such as the ability to tune for angle of arrival and polarization properties.

Abstract: An antenna element is provided that includes a frequency selective surface (FSS) portion on its primary radiating/receiving surface. The antenna element is conductively or capacitively coupled to an RF feed structure that can also include an FSS portion. In a preferred embodiment, the FSS antenna portion is located at least partially within the radiation pattern of a second antenna that operates in a frequency range for which the FSS is substantially transparent. In this way, signals being transferred to or from the second antenna through space can travel through the FSS antenna portion with little attenuation and/or reflection.