Dualband flexible antenna with segmented surface treatment
An antenna structure including a dual-band WiFi CPW antenna formed on a dielectric substrate and a frequency selective impedance surface formed on the substrate and at least partially surrounding the antenna. The antenna includes a ground plane defining a gap and an antenna radiating element including a radiating portion positioned proximate to the ground plane and a feed line extending into the gap. The frequency selective impedance surface can be a ring that is configured around the radiating portion of the radiating element, where the frequency selective impedance ring receives surface waves propagating along the dielectric substrate generated by the antenna.
1. An antenna structure comprising:
a dielectric substrate having an inner surface and an outer surface;
an antenna formed directly on the outer surface of the dielectric substrate; and
a frequency selective impedance element formed directly on the outer surface of the dielectric substrate and being configured around a radiating portion of a radiating element such that the frequency selective impedance element and the antenna form a co-planar structure, the frequency selective impedance element is a semi-circular ring, and the frequency selective impedance element receiving surface waves propagating along the dielectric substrate generated by the antenna.
2. The antenna structure according to claim 1 wherein the frequency selective impedance element is a segmented ring including a plurality of ring segments separated by gaps.
3. The antenna structure according to claim 2 wherein the gaps have a flared shape formed by end edges of the adjacent ring segments.
4. The antenna structure according to claim 1 wherein the radiating portion has a pentagon shape.
5. The antenna structure according to claim 1 wherein the antenna is a dual-band antenna and the radiating element includes a slot for rejecting frequencies between a first band and a second band.
6. The antenna structure according to claim 1 wherein the frequency selective impedance element is formed using a dielectric material with a dielectric constant different than that of the dielectric substrate.
7. The antenna structure according to claim 1 further comprising a CPW feed structure being electrically coupled to a ground plane and the radiating element.
8. The antenna structure according to claim 1 wherein the dielectric substrate is affixed to a vehicle window.
9. The antenna structure according to claim 1 further comprising an adhesive layer formed on the inner surface of the dielectric substrate.
10. The antenna structure according to claim 1 wherein the antenna includes transparent conductors.
11. The antenna structure according to claim 1 wherein the antenna and frequency selective impedance element are formed on a thin film substrate selected from the group consisting of mylar, Kapton, PET and flexible glass substrates.