TUNABLE SLEEVE ANTENNA

• US 3,798,654 A
• Filed: 08/16/1972
• Issued: 03/19/1974
• Est. Priority Date: 08/16/1972
• Status: Expired due to Term

• Current Assignee: Orion Industries Incorporated
• Original Assignee: Herbert R. Blaese, Louis J. Martino, Robert J. Steinhofer
• Inventors: Martino, Louis J., Blaese, Herbert R., Steinhofer, Robert J.
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/281,035
• Time in Patent Office: 580 Days
• Field of Search: 343/745,749,750,861
• US Class Current: 343/745
• CPC Class Codes: H01Q 9/14 Length of element or elements adjustable telescopic elements H01Q1/10

Abstract

A tunable antenna structure including an elongated radiating element, supported at one end, a resonant tuning coil coupled to the radiating element at the supporting end, and a tuning element electrically coupled to the tuning coil for varying the electrical characteristics of the coil and matching the antenna impedance to a transmission line. A flush mounting base for mounting the radiating element and tuning means with a moisture proof seal. Both fiberglass and metal whip antennas for half wavelength and quarter wavelength operation are described. The movable tuning element is at ground potential so that one'"'"''"'"'s body or hand capacitance does not affect resonance of the tuning coil during antenna tuning.

Claims

1. A tunable antenna structure for matching the impedance of said antenna structure to a transmission line, said antenna structure comprising:

an elongated radiating element extending from an electrically groundable support end to a free end;

a resonant tuning coil encased in a dielectric at said support end;

means for interconnecting said elongated radiating element at said support end to said transmission line;

an electrically conductive tuning sleeve element electrically coupled to said resonant tuning coil; and

conductive mounting means for movably mounting said electrically conductive tuning sleeve element in electrical and sliding contact with said support end and adjacent said tuning coil for varying the resonant frequency of said coil without hand capacity detuning.

2. A tunable antenna structure for matching the impedance of said antenna structure to a transmission line, said antenna structure comprising:

a thin tube extending from a support end to a free end;

an electrically groundable support base mounted to said tube support end for supporting said tube;

a multiple turn coil encased in a dielectric mounted within said tube at said support end;

A FIRST CONDUCTING WIRE CONNECTED TO ONE END OF SAID MULTIPLE TURN COIL AND EXTENDING WITHIN SAID TUBE TO SAID FREE END;

a second conductor means within said support base including a center conductor insulatably supported from said support base and means coupling said center conductor to the other end of said coil;

an electrically conductive tuning sleeve element electrically coupled to said multiple turn coil; and

conductive mounting means for movably mounting said electrically conductive tuning sleeve element in electrical and sliding contact with said support base and adjacent said multiple turn coil for varying the resonant frequency of said coil without hand capacity detuning.

3. An antenna structure as claimed in claim 2, including, means for connecting the other end of said multiple turn coil to said support base, and means for connecting said center conductor to one of said turns of said multiple turn coil adjacent said other end of said coil.

4. An antenna structure as claimed in claim 2, wherein said tuning element comprises:

a hollow conductive sleeve, surrounding at least a portion of said multiple turn coil; and

positioning means for locking said sleeve in position with respect to said coil.

5. An antenna structure as claimed in claim 4, wherein said support base includes a flange portion extending therefrom mounted to said tube;

said hollow, conductive sleeve movably mounted on said flange portion for introducing a variable electrical capacitance in the vicinity of said coil.

6. An antenna structure as claimed in claim 5, including means for threadably engaging said hollow, conductive sleeve with said flange portion.

7. An antenna structure as claimed in claim 5, wherein said positioning means comprises a locking set screw threadably engaging said hollow, conductive sleeve for detachable locking engagement with said flange portion.

8. An antenna structure as claimed in claim 2, wherein said support base includes, a cylindrical shoulder portion having a smaller diameter, threaded, elongated portion extending from a junction with said shoulder;

an O-ring mounted in said junction;

said antenna structure further including;

a mounting base comprising;

a flange, including means for flush mounting said flange; and

threaded cavity means within said flange for receiving said threaded, elongated portion of said support base;

said O-ring thereby sealingly engageable with said flange to form a moisture seal. a first conducting wire connected to one end of said multiple turn coil and extending within said tube to said free end;