High dynamic range RF power monitor

Patent metadata

Field	Value
Publication number	US-9791489-B2
Application number	US-201214005804-A
Country	US
Kind code	B2
Filing date	Mar 22, 2012
Priority date	Mar 22, 2011
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A device with at least one channel for measuring high dynamic range, radio frequency (RF) power levels over broad-ranging duty cycles includes a power sensor circuit comprising at least one logarithmic amplifier; at least one directional RF coupler electrically connected to the at least one power sensor; at least one RF attenuator electrically connected to the at least one RF coupler; and at least one sampling circuit electrically connected to the at least one RF attenuator and the at least one RF coupler. The at least one sampling circuit performs analog-to-digital conversion of electrical signals received to provide digitals signals for measuring the RF power level in the at least one channel.

First claim

We claim:

1. A device with at least one channel for measuring radio frequency (RF) power levels, comprising:
a power sensor circuit comprising at least one logarithmic amplifier for measuring RF power levels over a high dynamic range and full range of duty cycles used for magnetic resonance imaging (MRI);
at least one directional RF coupler electrically connected to said at least one power sensor circuit;
at least one RF attenuator electrically connected to said at least one directional RF coupler; and
at least one sampling circuit electrically connected to said at least one RF attenuator and said at least one directional RF coupler,
wherein said at least one sampling circuit performs analog-to-digital conversion of electrical signals received to provide digitals signals for measuring the RF power level in the at least one channel, and
wherein said at least one RF attenuator is configured to receive an RF signal from said at least one directional RF coupler and provide a signal to said power sensor circuit.

2. The device of claim 1 , further comprising a computer configured to communicate with said at least one sampling circuit to receive said digital signals.

3. The device of claim 2 , further comprising a display configured to communicate with said computer, wherein said computer is further configured to calculate measured peak power from said digital signals from said at least one channel in real time, and said display is configured to communicate with said computer to provide real-time display of said measured peak power.

4. The device of claim 3 , wherein said computer is further configured to calculate measured average power from said digital signals in real time from said at least one channel, and said display is configured to communicate with said computer to provide real-time display of said measured average power from said at least one channel.

5. The device of claim 1 , wherein the at least one channel is more than one channel, wherein each channel comprises a power sensor circuit comprising a logarithmic amplifier connected to a directional RF coupler electrically connected to a RF attenuator electrically connected to at least one sampling circuit, and
wherein each said sampling circuit is electrically also connected to each RF attenuator to provide multichannel RF measurements.

6. The device of claim 5 , wherein the at least one channel is four channels.

7. The device of claim 1 , wherein said high dynamic range, low duty cycle RF power levels are produced by a magnetic resonance imaging (MRI) system and said device is MRI compatible.

8. The device of claim 7 , wherein said device is adapted for monitoring RF exposure of a subject in said MRI system,
wherein said MRI system operates in a frequency range of 1 MHz to 400 MHz.

9. The device of claim 8 , further comprising a Q-hybrid transducer.

10. A method of monitoring radio frequency (RF) exposure proximate an RF emitting device, comprising connecting an RF monitoring system according to claim 1 to an RF power source of said RF emitting device.

11. The method of claim 10 , wherein said RF emitting device is a magnetic resonance imaging (MRI) system.

12. The method of claim 10 , wherein said RF power source is an RF coil of an MRI system.

13. The method of claim 10 , wherein said RF emitting device is at least one of a radar system or a telecommunications system, or a medical RF diathermy system, or a RF ablation system.

14. The device of claim 1 , wherein the at least one channel is a plurality of channels.

15. The device of claim 14 , wherein the at least one channel is six channels.

16. The device of claim 1 , wherein the high dynamic range is at least 40 dB.

17. The device of claim 1 , wherein the high dynamic range is at least 70 dB.

Assignees

• Bottomley Paul A
• Edelstein William
• El-Sharkawy Abdel-Monem M
• Qian Di
• Univ Johns Hopkins

Inventors

• Bottomley Paul A
• Edelstein William
• El-Sharkawy Abdel-Monem M
• Qian Di

Classifications

• G01R33/288

  Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room · CPC title

• G01R21/10

  by using square-law characteristics of circuit elements, e.g. diodes, to measure power absorbed by loads of known impedance (G01R21/02 takes precedence) · CPC title

• G01R21/00 Primary

  Arrangements for measuring electric power or power factor (G01R7/12 takes precedence) · CPC title

• G01R1/00

  Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00 (constructional details particular to {electromechanical} arrangements for measuring the electric consumption G01R11/02) · CPC title

• G06F2101/00

  Indexing scheme relating to the type of digital function generated · CPC title