The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 06, 1994
Filed:
Sep. 17, 1993
Eric N Rudie, Maple Grove, MN (US);
Stanley E Kluge, Albertville, MN (US);
Urologix, Inc., Minneapolis, MN (US);
Abstract
A catheter shaft carries a coaxial cable, the terminal end of which contains a dipole antenna with opposing first and second helical elements. The first and second helical elements originate from a common connection to an outer conductor of the coaxial cable. The first and second helical elements are formed by winding flat wire around an outer insulator of the coaxial cable near a terminal end of the coaxial cable. A tubular-shaped capacitor is connected between an inner conductor of the coaxial cable and a point on the second helical element where the resistive component of the antenna's impedance matches the characteristic impedance of the coaxial cable. This match minimizes reflective losses of the antenna, thereby maximizing power transfer to the antenna. The antenna has an effective electrical length which is equal to one half the wavelength of the radiation emitted, independent of the physical length of the antenna. The antenna also has a radiation length which can be adjusted by varying the number and pitch of turns of the flat wire and the location of the impedance matching point.