Regenerative feedback resonant circuit

1. A regenerative feedback resonant circuit for measuring a transient response in a loop, comprising:

a. an amplifier for generating a signal in the loop; and

b. a resonator having a resonant cavity and a material loaded within the cavity, wherein the amplified signal sent into the resonator from the amplifier produces a resonant frequency due to the material loaded cavity, and wherein a variation of the resonant frequency due to perturbations caused by an external source is measured by extracting a portion of the amplified signal to detect the external source.

2. The circuit of claim 1 wherein a directional coupler extracts a portion of the amplified signal from the resonator.

3. The circuit of claim 1 further comprising an antenna for extracting a portion of the amplified signal from the resonator.

4. The circuit of claim 1 further comprising a bandpass filter for rejecting frequencies outside a frequency band of the resonator.

5. The circuit of claim 2 further comprising a circulator for routing the portion of the extracted signal from the directional coupler to a receiver circuit.

6. The circuit of claim 1 wherein the resonator is one of a dielectric ring resonator, a split-post dielectric resonator, and a split-ring resonator.

7. The circuit of claim 1 wherein the perturbations are caused by at least one of the following external sources: an optical source, an electromagnetic source, a radiation source, a thermal source, an acoustic source, vibrations, movements, and a mechanical source.

8. The circuit of claim 1 wherein the material is selected from at least one of the following: a metal, a semiconductor, an insulator, a magnetic material, a dielectric material, a piezoelectric material, a ferroelectric material, a magnetostrictive material, an electrostrictive material, a superconductor, a ferromagnetic material, a multiferroic material, and a thermoelectric material.

9. The circuit of claim 1 wherein the resonator has an operating frequency in the microwave portion of the electromagnetic spectrum.

10. The circuit of claim 9 wherein the resonator has passive quality factors (Q stat ) ranging from 10 to 7,000.

11. The circuit of claim 9 wherein the resonator with the loaded material has positive feedback enhanced dynamic quality factors (Q dyn ) on the order of 10,000 to 15,000,000.

12. The circuit of claim 1 wherein the resonator includes a gap and a bore, and wherein electric fields are perpendicular across the gap and magnetic fields are longitudinal to the direction of the bore.

13. A method of measuring a transient response in a loop, comprising:

a. generating an amplified signal in the loop;

b. inputting the amplified signal into a resonator having a resonant cavity and a material loaded within the cavity to produce a resonant frequency of the resonator due to the material loaded cavity; and

c. measuring a variation of the resonant frequency due to perturbations caused by an external source by extracting a portion of the amplified signal to detect the external source.

14. The method of claim 13 further comprising rejecting frequencies outside a frequency band of the resonator.

15. The method of claim 13 further comprising routing the portion of the extracted signal to a receiver circuit.

16. The method of claim 13 wherein the resonator is one of a dielectric ring resonator, a split-post dielectric resonator, and a split-ring resonator.

17. The method of claim 13 wherein the perturbations are caused by at least one of the following external sources: an optical source, an electromagnetic source, a radiation source, a thermal source, an acoustic source, vibrations, movements, and a mechanical source.

18. The method of claim 13 wherein the material is selected from at least one of the following: a metal, a semiconductor, an insulator, a magnetic material, a dielectric material, a piezoelectric material, a ferroelectric material, a magnetostrictive material, an electrostrictive material, a superconductor, a ferromagnetic material, a multiferroic material, and a thermoelectric material.

19. The method of claim 13 wherein the resonator has an operating frequency in the microwave portion of the electromagnetic spectrum.

20. The method of claim 19 wherein the resonator has passive quality factors (Q stat ) ranging from 10 to 7,000.

21. The method of claim 19 wherein the resonator with the loaded material has positive feedback enhanced dynamic quality factors (Q dyn ) on the order of 10,000 to 15,000,000.

22. The method of claim 13 wherein the resonator includes a gap and a bore, and wherein electric fields are perpendicular across the gap and magnetic fields are longitudinal to the direction of the bore.

23. A sensor comprising:

a. an amplifier for generating a signal in a loop;

b. a resonator having a resonant cavity and a material loaded within the cavity, wherein the amplified signal is inputted into the resonator to produce a resonant frequency of the resonator due to the material loaded cavity, and wherein a variation of the resonant frequency due to perturbations caused by an external source is measured; and

c. a directional coupler or an antenna for extracting a portion of the amplified signal from the resonator to detect the external source.

24. A sensing method comprising:

a. generating an amplified signal in a loop;

b. inputting the amplified signal into a resonator having a resonant cavity and a material loaded within the cavity to produce a resonant frequency of the resonator due to the material loaded cavity;

c. measuring a variation of the resonant frequency due to perturbations caused by an external source; and

d. extracting a portion of the amplified signal from the resonator to detect the external source.