Claims
- 1. A system for measuring a free space electric field, said system comprising:
a ground connection; an ultrahigh impedance antenna positioned in the electric field for generating a signal from the electric field; an amplifier having an input port, wherein said amplifier generates an input bias current, said input bias current being combined with the signal to create an input potential at the input port; and an electrical circuit connected to said input port and said ground connection, said electrical circuit having at least one circuit element for controlling said input potential to stabilize said signal at said input port.
- 2. A system as recited in claim 1 wherein said circuit element is a resistor having a resistance in the range of 10 to 10,000 GΩ.
- 3. A system as recited in claim 1 wherein said electrical circuit establishes a feedback path for said amplifier.
- 4. A system as recited in claim 4 wherein said electrical circuit comprises a means for generating negative feedback for said amplifier below a selected cutoff frequency.
- 5. A system as recited in claim 4 wherein said electrical circuit comprises a means for generating high gain negative feedback for said amplifier below a selected cutoff frequency and substantially no feedback above said selected cutoff frequency.
- 6. A system as recited in claim 4 wherein said electrical circuit comprises a means for generating a high gain negative feedback for said amplifier below a first selected cutoff frequency ν1, a high gain negative feedback for said amplifier above a second selected cutoff frequency ν2, and substantially no feedback at frequencies between ν1 and ν2.
- 7. A system as recited in claim 1 wherein said amplifier has an input capacitance and said system further comprises a means for eliminating the effect of said input capacitance of said amplifier.
- 8. A system as recited in claim 7 wherein said eliminating means comprises a capacitor.
- 9. A system as recited in claim 8 wherein said eliminating means further comprises an amplifier having a gain of two.
- 10. A system as recited in claim 1 wherein said amplifier is selected from the group of amplifiers consisting of an operational amplifier, an instrumentation amplifier and a transistor.
- 11. A system for measuring a free space electric field, said system comprising:
a ground connection; an antenna positioned in the electric field for generating a substantially a.c. signal from the electric field; an amplifier having an input port, wherein said amplifier generates a substantially d.c. input bias current, said d.c. input bias current being combined with the a.c. signal to create an input potential at the input port; and an electrical circuit connected to said input port and said ground connection, said electrical circuit having at least one circuit element for draining said d.c. input potential to said ground connection to stabilize said a.c. signal at said input port.
- 12. A system as recited in claim 11 wherein said circuit element is a resistor having a resistance in the range of 10 to 10,000 GΩ.
- 13. A system as recited in claim 11 wherein said electrical circuit establishes a feedback path for said amplifier.
- 14. A system as recited in claim 13 wherein said electrical circuit comprises a means for generating negative feedback for said amplifier below a selected cutoff frequency.
- 15. A system as recited in claim 11 wherein said amplifier has an input capacitance and said system further comprises a means for eliminating the effect of said input capacitance of said amplifier.
- 16. A method for measuring a free space electric field, said method comprising the steps of:
positioning an ultrahigh impedance antenna in the electric field to generate a signal from the electric field; connecting said antenna to an input port of an amplifier, wherein said amplifier generates an input bias current, said input bias current being combined with the signal to create an input potential at the input port; and connecting an electrical circuit to said input port and to a ground connection, said electrical circuit having at least one circuit element for controlling said input potential to stabilize said signal at said input port.
- 17. A method as recited in claim 16 wherein said circuit element is a resistor having a resistance in the range of 10 to 10,000 GΩ.
- 18. A method as recited in claim 16 wherein said electrical circuit establishes a feedback path for said amplifier.
Parent Case Info
[0001] This application is a continuation-in-part of application Ser. No. 09/783,858 filed Feb. 13, 2001 which is currently pending. The contents of application Ser. No. 09/783,858 are incorporated herein by reference.
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09783858 |
Feb 2001 |
US |
Child |
10641325 |
Aug 2003 |
US |