Patent ID: 7477201

Claim:
An antenna comprising: a ground plane having a first corner and a second corner, the first corner being in spaced relation to the second corner, the first corner and the second corner lying along a first common edge of the ground plane; a first antenna element disposed at the first corner of the ground plane and including a first slot, and a second antenna element disposed at the second corner of the ground plane and including a second slot; and a first feed terminal coupled to the first antenna element and a second feed terminal coupled to the second antenna element, wherein the ground plane comprises a first reentrant perimeter that extends inward underneath at least a first portion of the first antenna element and wherein the ground plane comprises a second reentrant perimeter that extends inward underneath at least a second portion of the second antenna element, and wherein the at least first portion of the first antenna element and the at least second portion of the second antenna element do not overlie the ground plane, wherein a first current pattern is established by feeding the first antenna element via the first feed terminal and flows at least partially around the first slot and wherein a second current pattern is established by feeding the second antenna element via the second feed terminal and flows at least partially around the second slot, and wherein the first antenna element and the second antenna element are fed with an electromagnetic signal, the electromagnetic signal at the first antenna element being approximately 90 degrees shifted from the signal at the second antenna element, the first antenna element and the second antenna element forming an antenna structure, the antenna structure transmitting circularly polarized radiation.