Electromagnetic Field Power Density Monitoring System and Methods

• US 20090267846A1
• Filed: 04/28/2008
• Published: 10/29/2009
• Est. Priority Date: 04/28/2008
• Status: Abandoned Application

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Inventors: Johnson, Michael P., Thurston, Charles G.
• Application Number:
  US12/110,783
• Publication Number:
  US 20090267846A1
• Time in Patent Office: Days
• US Class Current: 343/703
• CPC Class Codes: G01R 29/0857 Dosimetry, i.e. measuring the time integral of radiation intensity; Level warning devices for personal safety use nuclear radiation dosimetry G01T
• CPC Class Codes: G08B 21/12 responsive to undesired emission of substances, e.g. pollution alarms

Abstract

Systems and methods for monitoring electromagnetic field power density are disclosed. The system includes a broadband antenna configured to convert a plurality of electromagnetic waves at a plurality of frequencies into a broadband signal. The system also includes a power adjustment system configured to passively selectively attenuate the broadband signal to provide a filtered output signal for a predetermined range of frequencies. The system further includes an output system configured provide an indicator to an end-user of the system if the filtered output signal exceeds a predetermined threshold level that characterizes a predetermined electromagnetic power density threshold.

Claims

1. A system for monitoring electromagnetic field power density, the system comprising:

a broadband antenna configured to convert a plurality of electromagnetic waves at a plurality of frequencies into a broadband signal;

a power adjustment system configured to passively selectively attenuate the broadband signal to provide a filtered output signal for a predetermined range of frequencies; and

an output system configured to provide an indicator to an end-user of the system if the filtered output signal exceeds a predetermined threshold level that characterizes a predetermined electromagnetic power density threshold.

2. The system of claim 1, wherein the power adjustment system further comprises a plurality of filters configured to selectively attenuate the broadband signal, each of the plurality of filters selectively attenuating the broadband signal at a predetermined range of frequencies.

3. The system of claim 1, further comprising a rectifier system configured to rectify the filtered output signal and to provide a rectified filtered output signal to the output system.

4. The system of claim 1, wherein the power adjustment system is configured to selectively attenuate the broadband signal over at least three octaves.

5. The system of claim 1, wherein the broadband antenna comprises a textile woven antenna.

6. The system of claim 1, wherein the broadband antenna comprises a spiral antenna.

7. The system of claim 1, wherein the predetermined level corresponds to a maximum permissible exposure (MPE) of a power density for an end user of the system.

8. The system of claim 7, wherein the MPE of a power density for the end user changes as a function of frequency.

9. The system of claim 1, the output system further comprises:

a light emitting diode (LED); and

an integrate and dump component configured to provide an oscillating signal to the LED when the filtered output signals exceeds the predetermined threshold level, causing the LED to flash.

10. The system of claim 1, wherein:

the filtered output signal comprises a plurality of filtered output the output signals, each of the output signals having a predetermined range of frequencies; and

the output system comprises a plurality of indicators, wherein each indicator is associated with at least one output signal of the plurality of output signals.

11. A garment that includes the system of claim 1 interwoven into a textile of the garment.

12. A passive circuit for monitoring electromagnetic field power density, the circuit comprising:

a broadband antenna configured to convert a plurality of electromagnetic waves at a plurality of different frequencies into a broadband signal;

a power adjustment system comprising a plurality of passive bandpass filters, each of the plurality of the bandpass filters configured to passively selectively attenuate the broadband signal at a predetermined band of frequencies and provide a filtered output signal;

an output system configured to passively output one of a visual, audio and tactile indicator to an end user of the circuit when the filtered output signal exceeds a predetermined threshold level that corresponds to a predetermined electromagnetic power density threshold.

13. The circuit of claim 12, wherein the output system comprises an integrate and dump component configured to provide an oscillating output signal when the filtered output signal exceeds the predetermined threshold level.

14. The circuit of claim 12, wherein the broadband antenna comprises a textile woven broadband antenna.

15. The circuit of claim 12, wherein the power adjustment system is configured to selectively attenuate the broadband signal at over at least three octaves.

16. The system of claim 12, wherein the predetermined level corresponds to a maximum permissible exposure (MPE) of an electromagnetic field power density for the end user.

17. The system of claim 16, wherein a given bandpass filter of the plurality of bandpass filters selectively attenuates a current of the broadband signal corresponding to the MPE of an electromagnetic field power density at a frequency within a passband of the given bandpass filter.

18. The circuit of claim 12, wherein:

the filtered output signal comprises a plurality of filtered output signals each having a predetermined frequency range; and

the output system comprises a plurality of indicators, wherein each indicator is associated with at least one of the plurality of filtered output signals.

19. A method for monitoring an electromagnetic field power density, the method comprising:

receiving a broadband signal;

passively selectively attenuating the broadband signal;

providing a filtered broadband signal;

activating an indicator if the filtered broadband signal exceeds a predetermined threshold level that corresponds to a predetermined electromagnetic power density threshold.

20. The method of claim 19, wherein the predetermined threshold level corresponds to a maximum permissive exposure (MPE) of an electromagnetic field power density for a person.

21. The method of claim 20, wherein the MPE of an electromagnetic power density for a person changes as a function of frequency.

22. The method of claim 19, wherein the broadband signal is received at a broadband antenna interwoven into a textile.