Variable mutual transductance tuned antenna

A tuning device comprising:

• a generally tubular metallic body having a central chamber therein and with a magnetic flux escaping window in the sidewalls thereof, first and second terminals in respective ends of said body, an electromagnetic flux producing coil in said central chamber, said coil being electrically connected between said first and second terminals, means inside said coil for intensifying the electromagnetic flux of said coil, and an inductance tuning loop positioned externally of said body adjacent said window in a position to produce a counter electromagnetic flux opposing that escaping through said window from said coil.

A tuning assembly comprising:

• a generally tubular metallic body having a central chamber opening into one end thereof and with a magnetic flux escaping window in the sidewalls thereof, a first terminal pin in said chamber adjacent said one end thereof, a second terminal pin adjacent the other end of said chamber, a coil in said chamber with respective ends of said coil being electrically connected to respective terminal pins, means inside said coil for intensifying the field produced by said coil and part of which passes through said window, and an electrically conductive ring around said body and positionable longitudinally of said window.

A tuning device for an antenna comprising:

• a coil, an electrically conductive metallic member in the external field of said coil for producing a flow of electricity in said member which opposes said external magnetic field, said member being positionable longitudinally of said external magnetic field to change its resistance to said magnetic field, and a metallic shield between said electrically conductive member and said coil, said shield having windows opposite said coil and said member whereby positioning said electrically conductive member axially of said coil changes its impedance.

An antenna comprising:

• an exposed length of conductor for generating or receiving radio waves, a ferromagnetic axially extending core, a coil of electrically conductive material over said core, one end of said coil being connected to a transmission line terminal and the other end being connected to said exposed length of conductor, a tubular metallic shield surrounding said coil, said shield having field escaping windows therein, and a ring of electrically conductive material opposite said windows, said ring being adjustable axially of said coil, and whereby the inductance of said coil can be varied by changing the position of said ring.

A variable mutual transductance tuning device, and the like, comprising:

• a helically wound coil which produces a magnetic field of generally torroidal shape when electricity flows therethrough, first means inside said coil for intensifying said magnetic field, a tubular metallic shield surrounding said coil, said shield having field escaping windows therein, a generally cylindrical body of electrical insulating body encasing said coil, first means and tubular shield and providing a exterior surface of said insulating material, an electrically conductive tuning ring supported by said insulating body in a manner electrically isolated from ground and said coil to produce an electrical flow around said ring in response to a change in said magnetic field coming through said window, and means for varying either the electrical flow around said ring or the magnetic coupling of said ring with the magnetic field coming through said window.