Ultra-wideband antenna

Abstract

An ultra-wideband antenna is formed from a coaxial cable passed through the center of a conductive tube. The center conductor of the coaxial cable is connected to an end of the conductive tube, and the shield of the coaxial cable is not electrically connected to any conductor. Two ferrite beads are disposed serially on the cable beneath the tube, spaced apart from the tube and spaced apart from one another. A centering spacer maintains the coaxial cable within the center of the tube.

What is claimed is: 
     
         1 . An ultra-wideband antenna comprising:
 a coaxial cable extending through the center of a conductive tube, a distal end of a center conductor of the coaxial cable electrically connected to a distal end of the conductive tube, a distal end of a shield of the coaxial cable not electrically connected to any conductor;   a first and a second ferrite bead disposed on the coaxial cable outwardly from a proximal end of the conductive tube, outside of the conductive tube, the first and second ferrite bead disposed serially on the coaxial cable, spaced apart from one another.   
     
     
         2 . The antenna of  claim 1 , further comprising a centering spacer disposed between the conductive tube and the coaxial cable, the centering spacer configured to maintain the coaxial cable substantially centered within the conductive tube. 
     
     
         3 . The antenna of  claim 2 , wherein the centering spacer is formed from an insulating material. 
     
     
         4 . The antenna of  claim 3 , wherein the centering spacer is formed from polyurethane foam. 
     
     
         5 . The antenna of  claim 1 , wherein the conductive tube is formed from brass, and wherein a wall of the tube is between 0.38 mm and 0.420 mm thick. 
     
     
         6 . The antenna of  claim 1 , wherein the shield of the coaxial cable terminates within the conductive tube, a distance of between 6.1 mm and 6.6 mm from the distal end of the conductive tube. 
     
     
         7 . The antenna of  claim 1 , wherein the first ferrite bead is spaced from a proximal end of the conductive tube by between 84.8 mm and 87.6 mm. 
     
     
         8 . The antenna of  claim 7 , wherein the second ferrite is spaced apart from the first ferrite bead by a distance of between 59 mm and 61 mm. 
     
     
         9 . The antenna of  claim 1 , wherein each of the first and second ferrite beads extends around the outer shield of the coaxial cable, and wherein the first and second ferrite beads are configured to affect a resonant point of the antenna. 
     
     
         10 . The antenna of  claim 1 , further comprising a mushroom-shaped housing configured to be installed in a lid of an underground pit, the housing comprising a rounded top portion unitarily formed with a male-threaded portion, the male-threaded portion configured to pass through an opening in the lid, the rounded top portion configured to extend above the lid. 
     
     
         11 . The antenna of  claim 10 , wherein the conductive tube extends into the rounded top portion a distance of between 0.40 and 0.49 inches. 
     
     
         12 . The antenna of  claim 10 , further comprising a female-threaded nut configured to mate with the male-threaded portion of the housing and secure the housing to the lid. 
     
     
         13 . An ultra-wideband antenna comprising:
 a conductive tube comprising a distal end and a proximal end;   a coaxial cable extending through the center of the conductive tube, the coaxial cable comprising a center conductor and a shield, a distal end of the center conductor electrically connected to the distal end of the conductive tube;   a first and a second ferrite bead disposed on the coaxial cable outwardly from the proximal end of the conductive tube, outside of the conductive tube, the first and second ferrite bead disposed serially on the coaxial cable, spaced apart from one another.   
     
     
         14 . The antenna of  claim 13 , a distal end of a shield of the coaxial cable not electrically connected to any conductor. 
     
     
         15 . The antenna of  claim 13 , further comprising an insulating centering spacer disposed between the conductive tube and the coaxial cable, the centering spacer configured to maintain the coaxial cable substantially centered within the conductive tube. 
     
     
         16 . The antenna of  claim 13 , further comprising a mushroom-shaped housing configured to be installed in a lid of an underground pit, the housing comprising a rounded top portion unitarily formed with a male-threaded portion, the male-threaded portion configured to pass through an opening in the lid, the rounded top portion configured to extend above the lid. 
     
     
         17 . The antenna of  claim 16 , wherein the conductive tube extends into the rounded top portion a distance of between 0.40 and 0.49 inches. 
     
     
         18 . The antenna of  claim 16 , further comprising a female-threaded nut configured to mate with the male-threaded portion of the housing and secure the housing to the lid. 
     
     
         19 . An ultra-wideband antenna comprising:
 a conductive tube comprising a distal end and a proximal end;   a coaxial cable extending through the center of the conductive tube, the coaxial cable comprising a center conductor and a shield, a distal end of the center conductor electrically connected to the distal end of the conductive tube; and   an insulating centering spacer disposed between the conductive tube and the coaxial cable, the centering spacer configured to maintain the coaxial cable substantially centered within the conductive tube.   
     
     
         20 . The antenna of  claim 19 , further comprising a first and a second ferrite bead disposed on the coaxial cable outwardly from the proximal end of the conductive tube, outside of the conductive tube, the first and second ferrite bead disposed serially on the coaxial cable, spaced apart from one another.