Coaxial cable shield filter

• US 5,091,707 A
• Filed: 08/13/1990
• Issued: 02/25/1992
• Est. Priority Date: 08/13/1990
• Status: Expired due to Term

• Current Assignee: Thomas R. Jokerst
• Original Assignee: Thomas B. Jokerst
• Inventors: Mundy, David M., Wollmerschauser, Steven M.
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/566,661
• Time in Patent Office: 561 Days
• Field of Search: 333/12, 333/167, 333/185, 333/184, 333/181, 336/229, 336/233
• US Class Current: 333/12
• CPC Class Codes: H03H 1/0007 of radio frequency interference filters
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus

Abstract

A coaxial cable shield filter for reducing RF signal interference from cable television lines is connected in series between a cable system coaxial cable and a television receiver. Each choke consists of a ferromagnetic toroidal core, with coaxial cable being wound about each toroidal core. The filter device attenuates secondary RF signals carried by the shielding of the coaxial cable that interfere with the primary signals carried by the cable'"'"'s center conductor.

Claims

1. A coaxial cable shield filter for use in attenuating "off-air" RF signals that are picked up and conducted by coaxial cable shielding, the filter comprising:

a housing;

an input connector mounted on the housing, and adapted to be connected with a coaxial cable;

an output connector mounted on the housing, and adapted to be connected with a coaxial cable;

an RF filter means in the housing interior; and

a conductor in the housing interior connecting the RF filter means to the input connector and the output connector, and arranged to connect the RF filter means in series with the shielding of a coaxial cable connected to the input connector and the shielding of a coaxial cable connected to the output connector;

the RF filter means includes a first toroid secured in the housing interior, the first toroid being constructed from ferromagnetic material;

and the RF filter means further includes a second toroid secured in the housing interior, the conductor being wrapped several times through the first and second toroids.

2. The filter of claim 1, wherein:

the second toroid secured in the housing interior is constructed of ferromagnetic material.

3. The filter of claim 2, wherein:

the first toroid attenuates RF signals in a low to middle television frequency band and the second toroid attenuates RF signals in a high to very high television frequency band.

4. A filter for reducing television picture interference caused by RF signals conducted on a coaxial cable shielding, the filter comprising:

a first and a second toroid;

a coaxial conductor with first and second ends, and having a center conductor and a shielding surrounding the center conductor;

said coaxial conductor being wound about said first and second toroids in series, thereby creating first and second chokes connected in series by the shielding of the coaxial conductor;

an input means provided at the first end of the coaxial conductor, the input means being adapted to be connected to a coaxial cable by an unskilled layperson; and

an output means provided at the second end of the coaxial conductor, the output means being adapted to be connected to a television receiver by an unskilled layperson.

5. The filter of claim 4 wherein:

said input means is a threaded female coaxial cable connector and said output means is a threaded male coaxial cable connector.

6. The filter of claim 4 wherein:

said first and second toroids are constructed of ferromagnetic material.

7. The filter of claim 6 wherein:

said first toroid is constructed of ferrite number 43 and said second toroid is constructed of powdered iron.

8. The filter of claim 7 wherein:

said first toroid attenuates RF signals in a low to middle television frequency band and said second toroid attenuates RF signals in a high to very high television frequency band.