Electromagnetic protection test and surveillance system

• US 6,987,392 B1
• Filed: 05/05/2004
• Issued: 01/17/2006
• Est. Priority Date: 05/05/2004
• Status: Expired due to Fees

• Current Assignee: North South Holdings Incorporated (Spherix Incorporated)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Hernandez, Arecio A., Hoyt, David George
• Primary Examiner(s): Benson, Walter
• Application Number:
  US10/839,835
• Publication Number:
  US 20060006881A1
• Time in Patent Office: 622 Days
• Field of Search: 174/35.R, 324/95, 324/612, 324/627, 324/632, 342/174
• US Class Current: 324/627
• CPC Class Codes: G01R 29/0835 Testing shielding, e.g. for efficiency

Abstract

A test architecture performs calibration and site verification testing of the effectiveness of a radiation shielding structure within which electronic equipment is housed. An external subsystem is outside a shielding cabinet, and an internal subsystem resides with the electronic equipment within the shielded equipment housing proper. The external subsystem includes a host computer, which controls the operation of transmit and receive subsystems. An external receiver is selectively coupled by the host processor to either an RF receive antenna or to a current sense probe. All control signals from the external subsystem are conveyed into the shielded cabinet by way of fiber optic links, in order to preserve the shielding effectiveness of the cabinet. Having the source of test signals and its associated transmission antenna located within the shielded cabinet serves to minimize the impact of such signals on circuits within the environment outside the cabinet.

Claims

1. A method of testing the RF-shielding effectiveness of an RF-shielding enclosure for electronic equipment enclosed therein comprising the steps of:

(a) deploying said RF-shielding enclosure containing said electronic equipment to an installation field site containing other electronic equipment;

(b) transmitting RF energy from an RF transmitter enclosed within said RF-shielding enclosure;

(c) measuring RF energy received at an RF receiver external to said RF-shielding enclosure;

(d) providing an indication of the effectiveness of said RF shielding to block the transmission therethrough of said RF energy transmitted by said enclosed RF transmitter;

(e) coupling power through a power line containing a power supply filter to said electronic equipment installed within said RF-shielding enclosure;

(f) coupling RF energy from said RF transmitter enclosed within said RF-shielding enclosure to a location of said power line inside said enclosure;

(g) coupling said RF receiver to a location of said power line outside said enclosure;

(h) measuring RF energy coupled to said power line by said RF transmitter in step (f) and received by said RF receiver; and

(i) providing an indication of the effectiveness of said power supply filter to block the transmission therethrough of said RF energy coupled to said power line in step (f).

2. The method according to claim 1, wherein step (b) comprises transmitting RF energy from said RF transmitter by way of a generally flat RF antenna mounted at the interior side of a door of said enclosure.

3. A method of testing the RF-shielding effectiveness of an RF-shielding enclosure for electronic equipment enclosed therein comprising the steps of:

(a) deploying said RF-shielding enclosure containing said electronic equipment to an installation field site containing other electronic equipment;

(b) transmitting RF energy from an RF transmitter enclosed within said RF-shielding enclosure;

(c) measuring RF energy received at an RF receiver external to said RF-shielding enclosure; and

(d) providing an indication of the effectiveness of said RF shielding to block the transmission therethrough of said RF energy transmitted by said enclosed RF transmitter; and

wherein

step (b) comprises transmitting RF energy from said RF transmitter by way of a generally flat RF antenna mounted at the interior side of a door of said enclosure; and

wherein step (c) comprises receiving RF energy transmitted from said RF transmitter at a RF receiving antenna external to said RF-shielding enclosure, and being configured to have its boresight axis pointable to a prescribed location of said generally flat RF antenna for each of an open and a closed condition of said door.

4. The method according to claim 3, wherein said generally flat RF antenna comprises a ferrite-loaded log spiral antenna, and said RF receiving antenna comprises a pivotable log periodic antenna.

5. A method of testing the RF-shielding effectiveness of an RF-shielding enclosure for electronic equipment enclosed therein comprising the steps of:

i—

calibrating the RF-shielding effectiveness of said RF-shielding enclosure by;

(a) mounting RF a generally flat transmission antenna on an interior side of a door of said RF-shielding enclosure;

(b) mounting an RF receive antenna external to said RF-shielding enclosure;

(c) prior to deploying said RP-shielding enclosure containing said electronic equipment to an installation field site containing other electronic equipment, opening said door of said enclosure and transmitting RF energy from said RF transmission antenna mounted thereon;

(d) measuring RF energy received at an RF antenna outside said RF-shielding enclosure and pointed at said RF transmission antenna as mounted on said open door; and

(e) generating a baseline attenuation measurement relative to RF energy received in step (d); and

ii—

verifying the RF-shielding effectiveness of said RF-shielding enclosure as calibrated in step i by;

(f) deploying said RF-shielding enclosure containing said electronic equipment to an installation field site containing other electronic equipment, closing said door of said enclosure and transmitting RF energy from said RF transmission antenna mounted thereon;

(g) measuring RF energy received at an RF antenna outside said RF-shielding enclosure and pointed at said RF transmission antenna as mounted on said closed door;

(h) providing an indication of the effectiveness of said RF shielding to block the transmission of RF energy therethrough, in accordance with a prescribed relationship between said RF energy measured in step (g) and said baseline attenuation measurement generated in step (e).

6. The method according to claim 5, wherein step (f) includes the steps of:

(f1) deploying said RF-shielding enclosure containing said electronic equipment to an installation field site containing other electronic equipment, and closing said door of said enclosure;

(f2) measuring RF energy at a first prescribed frequency received at said RF antenna outside said RF-shielding enclosure and pointed at said RF transmission antenna as mounted on said closed door without transmitting RF energy from said RF transmission antenna within said enclosure;

(f3) in response to RP energy measured in step (f2) having a prescribed relationship relative to said baseline attenuation measurement generated in step (e), transmitting RF energy from said RF transmission antenna at said first prescribed frequency, but otherwise not transmitting at said first prescribed frequency.

7. The method according to claim 6, wherein step (f2) further includes,

in response to RF energy measured at said first prescribed frequency not having said prescribed relationship relative to said baseline attenuation measurement generated in step (e), measuring RF energy at a second prescribed frequency received at said RF antenna without transmitting RF energy from said RF transmission antenna within said enclosure, and

step (f3) comprises,

in response to RF energy at said second prescribed frequency measured in step (f2) having a prescribed relationship relative to said baseline attenuation measurement generated in step (e), transmitting RF energy from said RF transmission antenna at said second prescribed frequency, but otherwise not transmitting at said second prescribed frequency.

8. The method according to claim 5, wherein said RF transmission antenna comprises a ferrite-loaded log spiral antenna, and said RF receiving antenna comprises a pivotable log periodic antenna.

9. A method of testing the RF-shielding effectiveness of an RF-shielding enclosure for electronic equipment enclosed therein comprising the steps of:

(a) deploying said RF-shielding enclosure containing said electronic equipment and an RF transmitter and associated RF transmission antenna to an installation field site containing other electronic equipment;

(b) for a closed condition of said enclosure and without transmitting RF energy from said RF transmitter, measuring ambient RF energy over a prescribed band of frequencies at an RF receive antenna external to said enclosure;

(c) in response to ambient RF energy measured in step (b) being less than a predetermined baseline at an RF frequency within said prescribed band of RF frequencies, causing said RF transmitter to transmit RF energy at said RF frequency;

(d) measuring RF energy at said RF frequency received at said RF receive antenna; and

(e) providing an indication of the effectiveness of said RF shielding to block the transmission therethrough of said RF energy at said RF frequency as transmitted in step (c) and measured in step (d);

wherein step (c) comprises transmitting RF energy from said RF transmitter by way of a generally flat RF antenna mounted at the interior side of a door of said enclosure.

10. The method according to claim 9, wherein step (c) further comprises, in response to ambient RF energy measured in step (b) not being less than said predetermined baseline at said RF frequency within said prescribed band of RF frequencies, causing said RF transmitter to transmit RF energy at another RF frequency;

and wherein step (d) comprises measuring RF energy at said another RF frequency received at said RF receive antenna; and

step (e) comprises providing an indication of the effectiveness of said RF shielding to block the transmission therethrough of said RF energy at said another RF frequency as transmitted in step (c) and measured in step (d).

11. The method according to claim 10, wherein step (d) comprises receiving RF energy transmitted from said RF transmitter at a RF receiving antenna external to said RF-shielding enclosure, and being configured have its boresight axis pointable to a prescribed location of said generally flat RP antenna for each of an open and a closed condition of said door.

12. The method according to claim 11, wherein said generally flat RF antenna comprises a ferrite-loaded log spiral antenna, and said RF receiving antenna comprises a pivotable log periodic antenna.

13. A system for testing the RF-shielding effectiveness of an RF-shielding enclosure for electronic equipment enclosed therein, when said RF-shielding enclosure and said electronic equipment enclosed therein being deployed to an installation field site containing other electronic equipment, said system comprising:

an RF transmitter enclosed within said RF-shielding enclosure, and being operative to transmit RF energy from an RF transmit antenna internal to said RF-shielding enclosure wherein said RF transmit antenna a generally flat RF transmit antenna mounted at an interior side of a door of said enclosure;

an RF receive antenna external to said RF-shielding enclosure and coupled to an RF receiver which is operative to measure RF energy as received by said RF receive antenna;

a control processor which is coupled to said RF transmitter and said RF receiver and is operative to derive an indication of the effectiveness of said RF shielding to block the transmission therethrough of RF energy transmitted by said RF-transmitter; and

a power supply filter coupled a power line for said electronic equipment installed within said RF-shielding enclosure, and wherein said RF transmitter is operative to couple RF energy to a location of said power line inside said RF-shielding enclosure, and said RF receiver is controllably coupled to a location of said power line outside said enclosure, and is operative to measure RF energy as coupled to said power line by said RF transmitter and filtered by said power supply filter, and wherein said control processor is operative to provide an indication of the effectiveness of said power supply filter to block the transmission therethrough of said RF energy coupled to said power line by said RF transmitter.

14. The system according to claim 13, wherein said RF receive antenna is configured to have its boresight axis pointable to a prescribed location of said generally flat RF antenna for each of an open and a closed condition of said door.

15. The system according to claim 14, wherein said generally flat RF antenna comprises a ferrite-loaded log spiral antenna, and said RF receive antenna comprises a pivotable log periodic antenna, that is configured to be pointed at 45°

relative to said generally flat RF antenna so as to be capable of receiving both vertical and horizontal polarized components of RF transmissions from said generally flat RF antenna.

16. The system according to claim 13, wherein said RF receiver comprises a narrow bandwidth RF receiver, and said RF transmitter and said RF receiver are synchronized to a common clock.

17. The system according to claim 13, wherein said control processor is coupled to said RF transmitter within said RF-shielding enclosure by way of a fiber-optic communication path.

18. A system for testing the RF-shielding effectiveness of an RF-shielding enclosure for electronic equipment enclosed therein, when said RF-shielding enclosure and said electronic equipment enclosed therein being deployed to an installation field site containing other electronic equipment, said system comprising:

an RF transmitter enclosed within said RF-shielding enclosure, and being operative to transmit RF energy from an RF transmit antenna internal to said RF-shielding enclosure wherein said RF transmit antenna a generally flat RF transmit antenna mounted at an interior side of a door of said enclosure;

an RF receive antenna external to said RF-shielding enclosure and coupled to an RF receiver which is operative to measure RF energy as received by said RF receive antenna; and

a control processor which is coupled to said RF transmitter and said RF receiver and is operative to derive an indication of the effectiveness of said RF shielding to block the transmission therethrough of RF energy transmitted by said RF transmitter; and

wherein said control processor is operative, for a closed condition of said enclosure and without transmitting RF energy from said RF transmitter, to measure ambient RF energy over a prescribed band of frequencies at an RF receive antenna and, in response to measuring ambient RF energy being less than a predetermined baseline at an RF frequency within said prescribed band of RF frequencies, to cause said RF transmitter to transmit RF energy at said RF frequency.

19. The system according to claim 18, wherein said control processor is further operative to measure RF energy at said RF frequency received at said RF receive antenna, and to provide an indication of the effectiveness of said RF shielding to block the transmission therethrough of said RF energy at said RF frequency.