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:
May. 08, 1990
Filed:
Feb. 08, 1988
George Ploussios, Andover, MA (US);
Other;
Abstract
A resonant helical antenna capable of being tuned electronically over a broad range of frequencies. The helical turns of the radiating portion of the antenna are formed of tubular material which may be in the form of a single length of tubing or may comprise a number of parallel coaxial cables with their outer conductors in electrical contact. The antenna is tuned by a series of oppositely poled pairs of diodes that are connected at spaced points to the radiating coils of the antenna. When the diodes are biased to be conducive, a section of the radiating helix is short-circuited. Bias voltages to control the diodes are provided by leads inside the radiating turns of the helix. Each lead for a pair of diodes emerges at a point electrically balanced between the two spaced points that are connected to the associated diodes. No r-f potential exists between the outer and inner conductor of the radiating runs at the point where the bias lead emerges, so no r-f current flows in the bias lead wires. The antenna may include spaced cpacitance elements and may be in the form of a monopole helical antenna or it may be in the form of a dipole antenna with two oppositely-disposed arms.