Apparataus and method for reducing radio frequency noise

• US 4,992,060 A
• Filed: 10/10/1989
• Issued: 02/12/1991
• Est. Priority Date: 06/28/1989
• Status: Expired due to Fees

• Current Assignee: Greentree Technologies, Inc.
• Original Assignee: Greentree Technologies, Inc.
• Inventors: Meyer, Dennis R.
• Primary Examiner(s): DESMOND, EUGENE
• Application Number:
  US07/419,100
• Time in Patent Office: 490 Days
• Field of Search: 439/607, 439/610, 439/620, 333/12
• US Class Current: 439/620.21
• CPC Class Codes: H01R 13/6464 by adding capacitive elements
• CPC Class Codes: H01R 13/6477 by variation of dielectric properties
• CPC Class Codes: H01R 13/6581 Shield structure
• CPC Class Codes: H04B 15/02 Reducing interference from electric apparatus by means located at or near the interfering apparatus

Abstract

A device for filtering radio frequency noise emanating from one or more axially extending conductors. The device includes a conductive shell which is spaced axially from the conductor or conductors. A ferrite core is fitted intermediate, and in engagement with, both the conductor or conductors and the shell. The ferrite core, thereby, functions to provide substantially increased series impedance in the conductor or conductors and to concurrently provide a common dielectric for multiple distributed, bypass capacitors along the conductor or conductors.

Claims

1. Apparatus for reducing radio frequency noise emanating from a transmission line interconnecting electronic devices, wherein the transmission line includes a conductive connector housing at at least one end thereof, comprising:

a ferrite core received and held within the connector housing, said ferrite core surrounding and engaging, within the connector housing, a shield surrounding all conductors passing through said ferrite core;

wherein said ferrite core functions to provide substantially increased series impedance in said conductors and a common dielectric for multiple, distributed, bypass capacitors along said conductors.

2. Apparatus in accordance with claim 1 wherein the connector housing has an axial dimension, and wherein said ferrite core has an axial dimension less than the axial dimension of the connector housing.

3. Apparatus in accordance with claim 1 wherein said ferrite core is bifurcated along a plane to divide said core into two substantially equal-in-size, generally symmetrical portions.

4. Apparatus in accordance with claim 1 wherein the transmission line connector housing has an internal cavity defined therewithin by an internal wall of the housing, and wherein said ferrite core has an outer surface substantially conforming to the internal wall of the connector housing defining the cavity therewithin.

5. Apparatus for use with an electrically conductive connector plug at at least one end of a transmission line for interconnecting electronic devices or connecting an electronic device to a power source, said apparatus for reducing radio frequency noise which would normally emanate from, or be received by, the transmission line, comprising:

a ferrite core, bifurcated along a plane to define two portions thereof, said core having an outer surface, when the bifurcated portions are assembled together, substantially conforming to an inner wall of the connector plug, which wall defines a cavity therewithin, so that said core is received and held within the connector plug to surround and engage a shield surrounding conductors going to various connections of the connector plug;

wherein said ferrite core functions to provide substantially increased series impedance in the conductors and a common dielectric for multiple, distributed, bypass capacitors along the conductors.

6. Apparatus in accordance with claim 5 further comprising clamping means, securable to the inner wall of the connector plug, for holding a bundle comprising the conductors going to the various connections of the connector plug in order to facilitate alignment, strain relief, and grounding of said shield.

7. Apparatus in accordance with claim 5 wherein the connector plug has an axial dimension, and wherein said ferrite core has an axial dimension less than the axial dimension of the connector plug.

8. A method for filtering radio frequency noise emanating from a transmission line having a conductive connector housing at one end thereof by forming a plurality of distributed, bypass capacitors, comprising the steps of:

(a) providing a ferrite core dielectric having an axially-extending channel formed therein;

(b) disassembling the connector plug shell to expose a bundle of data conductors encircled by a shield;

(c) feeding the bundle of shield-encircled data conductors through the axially-extending channel formed in the ferrite core; and

(d) seating the ferrite core within the connector plug shell and reassembling the plug shell with the ferrite core in engagement with the connector plug shell and the shield-encircled data conductors;

(e) wherein the shield and data conductors comprise, on the one hand, a first plate of various distributed, bypass capacitors, and the connector plug shell, on the other hand, comprises the second plate of the various capacitors.

9. Apparatus for filtering radio frequency interference emanating from a conductor, comprising:

(a) a conductive connector housing spaced from the conductor; and

(b) a ferrite core fitted intermediate, and in engagement with, the conductor and said housing;

(c) wherein said ferrite core functions to provide substantially increased series impedance in the conductor; and

(d) wherein said ferrite core concurrently functions to provide a common dielectric for multiple distributed, bypass capacitors along the conductor.

10. Apparatus for filtering radio frequency interference emanating from a conductor, comprising:

(a) a conductive plug shell spaced radially from the conductor; and

(b) a ferrite core fitted intermediate, and in engagement with, the conductor and said shell;

(c) wherein said ferrite core functions to provide substantially increased series impedance in the conductor; and

(d) wherein said ferrite core concurrently functions to provide a common dielectric for multiple distributed, bypass capacitors along the conductor.

11. Apparatus in accordance with claim 10 wherein said conductive plug shell is spaced radially outwardly from the conductor and substantially encircles the conductor, and wherein said ferrite core is in engagement with the conductor and said plug shell substantially along full circumferential surfaces of the conductor and said shell.

12. Apparatus for effecting filtering of radio frequency noise emanating from a plurality of axially extending conductors, comprising:

(a) a conductive shell spaced axially from the conductors; and

(b) a ferrite core fitted intermediate, and in engagement with, the conductors and said shell;

(c) wherein said ferrite core functions to provide substantially increased series impedance in the conductors; and

(d) wherein said ferrite core concurrently functions to provide a common dielectric for multiple distributed, bypass capacitors along the conductors.

13. Apparatus in accordance with claim 12 wherein said ferrite core is divided into portions.

14. Apparatus for attenuating the high frequency content of signals transmitted via conductor means at least partially enclosed by a conductive connector plug, comprising:

(a) a shield made of a conducting material, surrounding the conductor means substantially along the length of the shield inside the conductor plug, forming a first member of a three-member laminar assembly within the connector plug, the connector plug forming a second member of said three-member laminar assembly; and

(b) a ferrite core intermediate, and in engagement with, the connector plug and said shield, said ferrite core forming a third member of said three-member laminar assembly;

(c) wherein said three-member laminar assembly utilizes dielectric and inductive properties of said ferrite core to provide a controlled low pass filter for signals transmitted via conductors of said conductor means and to provide a low impedance electrical path to radio frequency currents between said shield and the connector plug, and wherein said ferrite core functions to provide substantially increased series impedance in said shield and a common dielectric for multiple distributed, bypass capacitors along said shield.

15. Apparatus in accordance with claim 14, wherein said shield passes adjacent an inner wall defined by an aperture passing axially through said ferrite core, and wherein the connector plug engages an outer wall of said ferrite core.

16. Apparatus in accordance with claim 14 wherein said ferrite core includes a plurality of ferrite sections.

17. Apparatus in accordance with claim 14 wherein the conductor means comprises a plurality of separate conductors, and wherein said ferrite core comprises a block of ferrite having a first end and a second end, said block having an axially extending hole, extending through said block from said first end to said second end, said separate conductors passing through said hold.

18. An interference suppressing connector adapted for terminating a multiple conductor communications cable of the type having an overall longitudinal electrically conductive shield, the connector comprising:

an electrically conductive housing adapted to be connected to an electrical ground, said housing including shield contact means positioned within the interior of said housing and adapted for establishing electrical contact between an exposed portion of said cable shield and said housing; and

a ferrite body positioned within the interior of said housing and adjacent said shield contact means, said body having a longitudinal passageway which is adapted to receive the cable therethrough;

wherein a cable is adapted to be positioned to extend through the ferrite body and with a portion of the cable shield in contact with said shield contact means, so that the electrically conductive housing, ferrite body and cable shield form a filter to suppress interference in the cable shield.

19. The connector of claim 18 wherein said shield contact means comprises an electrically conductive wall with an opening therein adapted to retain the cable, and wherein said conductive wall and portions of said housing define a cavity for receipt therein of said ferrite body.

20. An interference suppressing connector assembly, comprising:

a multiple conductor communications cable having an overall longitudinal electrically conductive shield, said cable having a terminal end portion and with at least the terminal end portion of said shield being exposed;

an electrically conductive housing adapted to be connected to an electrical ground, said housing having a generally hollow interior receiving the terminal end portion of said cable therein and including shield contact means positioned within the interior of said housing for establishing electrical contact between said exposed portion of said cable shield and said housing; and

a ferrite body positioned within the interior of said housing and adjacent said shield contact means, with said body having a longitudinal passageway which receives said cable therethrough;

wherein said electrically conductive housing, ferrite body, and cable shield form a filter to suppress interference in said cable shield.

21. The connector of claim 20 wherein said shield contact means comprises an electrically conductive wall with an opening therein to retain the cable, and wherein said conductive wall and portions of said housing define a cavity for receipt therein of said ferrite body.