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:
Aug. 29, 1989
Filed:
Aug. 24, 1987
George Ploussios, Andover, MA (US);
Other;
Abstract
A tunable helical antenna consists of a central support of dielectric material having a helical channel in the outer surface of the support. This channel, which may be square, rectangular or of other shape in cross-section, is plated with a conductive material such as copper. Biasing coaxial cables for controlling the tuning of the antenna are then placed within the channel and the channel sealed by a conductive cover. The plated surface becomes the helical radiating element of the antenna while the leads enclosed in the channel are isolated from r-f currents which are confined to the outer surface of the helix coating and conductive cover. The helical channel in the support may be formed by machining or the support may be molded with the helical channel as an integral part. Either way, precision control over the channel dimensions is readily attained. Pairs of oppositely-poled diodes are connected to spaced points on the radiating element. The conductivity of the diodes is controlled through the biasing cables to adjust the electrical length of the radiating element. The helical channel in the support may be formed by machining or the support may be molded with the helical channel as an integral part. Either way, precision control over the channel dimensions is readily attained.