Patent ID: 8325101

Claim:
An apparatus comprising a cross-dipole antenna, the cross-dipole antenna comprising: a coaxial structure having a center conductor and an outer shield having an outer diameter with corresponding radius R; a plurality of conductive arms comprising at least a first arm, a second arm, a third arm, and a fourth arm, wherein the plurality lie generally in a plane and are spaced apart from each other by about 90 degrees, such that a proximal end of each of the plurality of arms is arranged near a center point and wherein each of the plurality of arms extends generally outward at a distal end, wherein: the first arm is electrically coupled to the center conductor at a proximal end and has a first predetermined effective electrical length; the second arm is electrically coupled to the center conductor at a proximal end and has a second predetermined effective electrical length different from the first predetermined length; the third arm is electrically coupled to the outer shield at a proximal end and has a third predetermined effective electrical length, wherein the third predetermined length is equal to the sum of the first predetermined effective electrical length and 0.3 to 1.2 times the radius R, the third arm extending opposite the first arm such that the third arm and the first arm form a first dipole; and the fourth arm is electrically coupled to the outer shield at a proximal end and has a fourth predetermined effective electrical length, wherein the fourth predetermined effective electrical length is equal to the sum of the second predetermined effective electrical length and 0.15 to 1.5 times the radius R, the fourth arm extending opposite the second arm such that the fourth arm and the second arm form a second dipole; wherein one or more of the first predetermined effective electrical length, the second effective electrical length, the third effective electrical length, or the fourth effective electrical length is physically shorter than its predetermined effective electrical length.