Near field free space anisotropic materials characterization

• US 7,791,355 B1
• Filed: 10/30/2007
• Issued: 09/07/2010
• Est. Priority Date: 10/30/2007
• Status: Active Grant

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Esher, Justin, Gamroth, Nicholas, Dean, James, Derov, John S.
• Primary Examiner(s): Dole; Timothy J
• Assistant Examiner(s): ZHU, JOHN X
• Application Number:
  US11/998,980
• Time in Patent Office: 1,043 Days
• Field of Search: 324/637, 324/639, 324/642
• US Class Current: 324/637
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01R 29/0871 Complete apparatus or systems; circuits, e.g. receivers or amplifiers G01R29/0878, G01R29/0892 take precedence; dosimeters, warning devices G01R29/0857

Abstract

An automated computer controlled electrical materials characterization system in which a material sample is subjected to focused near field polarization controlled microwave electrical energy radiation. Response of the material sample to either of reflected or transmitted/refracted microwave radiation is determined by a microwave energy sensor disposable in a range of physical locations with respect to the sample. Automated and unattended operation of the characterization system by way of disclosed computer software is provided. Computer positioned, lens equipped, microwave antenna horn elements provide source and reception functions for the sample received and discharged microwave radiation. Output signal polarization response from the sample examination is especially considered. The disclosed system is especially suited to characterization of “negative index” electrical materials and has utility with a variety of other materials.

Claims

1. Near field, focusing horn beamed, spot microwave energy responsive material examination apparatus comprising the combination of:

a plurality of focused microwave transducer horn antenna elements each disposed on a distinct, selected trajectory, first drive type responsive, movable support element of said material examination apparatus;

a focused spot material sample capturing apparatus to capture a microwave energy responsive material sample, the capturing apparatus being disposed in a central near field location with respect to the selected trajectory of said horn antenna elements;

each of said selected trajectory first drive type responsive movable support elements further including a second drive type apparatus to drive said respective transducer horn antenna element a radial distance with respect to said material sample capturing apparatus and a third drive type apparatus to drive said respective microwave transducer horn antenna element signal about a polarization angle;

a first of said microwave transducer horn antenna elements being a source of microwave energy spot focused on said microwave energy responsive material sample and a second of said microwave transducer horn antenna elements comprising a microwave receiver apparatus also spot focused on said microwave energy responsive material sample with one of said focused microwave transducer horn antenna elements being first drive type responsive around said trajectory with respect to another of said focused microwave transducer horn antenna elements; and

programmed electronic computer apparatus connected with said first second and third drive types and in established sequence control of said material examination apparatus following an operator initiation event;

said first drive type responsive movable elements and related of said antenna horn elements being position adjustable in response to both positive index and negative index electromagnetic characteristic determined signals received from said energy responsive material sample.

2. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 1 wherein said focused microwave transducer horn antenna elements include a first spot focused microwave energy transmitter horn antenna element and a second spot focused microwave energy receiving horn antenna element each disposed on a circumferentially accessed element of said material examination apparatus.

3. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 1 wherein positive index and negative index electromagnetic characteristic determined signals relate to one of magnetic field responsive characteristics and electrical field responsive characteristics of said material sample.

4. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 3 wherein said magnetic field responsive characteristics and electrical field responsive characteristics include permeability, permittivity and anisotropy characteristics of said material sample.

5. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 1 wherein said microwave transducer horn antenna elements each include a microwave lens element adjacent a signal communication port thereof.

6. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 1 wherein said first drive type, said second drive type and said third drive type each include a stepping motor electrical to mechanical transducer.

7. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 1 wherein said second of said microwave transducer horn antenna elements comprises a microwave receiver apparatus is responsive to one of microwave electromagnetic energy reflected from said captured material sample and microwave energy refracted during transmission through said captured material sample.

8. The near field focusing horn beamed, spot microwave energy responsive material examination apparatus of claim 1 wherein said horn antenna elements selected trajectory is coincident and circular in shape for each of said horn antenna elements.

9. A near field, computer controlled free space spot microwave materials examination method comprising the steps of:

mounting a sample of the materials adjacent a focal point of a near field sample illuminator and a near field sample emissions receptor adapted to travel along a closed travel trajectory azimuth path;

illuminating said mounted sample with waveguide generate near field spot focused microwave energy of selected wavelength, selected radiation pattern, selected polarization angle and selected azimuth angle with respect to said mounted sample;

driving one of said near field sample illuminator and said near field sample emissions receptor through plural positions along said closed travel trajectory azimuth path under operator initiated computer control while collecting sample determined emissions;

recording a data sequence of said sample determined emissions found along said closed travel trajectory azimuth path and trajectory path position identifications relating thereto in response to achievement of a plurality of driven positions along said travel trajectory path;

said achieved plurality of driven positions along said travel trajectory path including positions determined by negative index of refraction related electromagnetic characteristics in said near field free space examined materials; and

examining said data sequence of sample determined emissions and trajectory path positions relating thereto for emission amplitude and trajectory path angular position relating data characteristic of said near field free space examined materials.

10. The near field, computer controlled free space spot microwave materials examination method of claim 9 wherein said collecting of sample determined emissions includes collecting one of sample reflecting emissions and sample refracting emissions from said mounted sample.

11. The near field, computer controlled free space spot microwave materials examination method of claim 9 wherein said step of illuminating said mounted sample with waveguide generated near field spot focused microwave energy includes the step of supplying said illuminating microwave energy from a lens focusing horn waveguide operating below cutoff microwave frequency.

12. The near field, computer controlled free space spot microwave materials examination method of claim 9 wherein said step of examining said data sequence of sample determined emissions and trajectory path positions relating thereto is responsive to one of sample permittivity, sample permeability, sample refraction index and sample anisotropy determined microwave signals.

13. The near field, computer controlled free space spot microwave materials examination method of claim 9 further including driving said sample illuminator through a plurality of sample electromagnetic characteristics related positions along said closed travel trajectory azimuth path.

14. The near field, computer controlled free space spot microwave materials examination method of claim 9 further including driving said sample receptor through a plurality of sample electromagnetic characteristics related positions along said closed travel trajectory azimuth path.

15. The near field, computer controlled free space spot microwave materials examination method of claim 9 wherein at least one of said sample emissions receptor and said sample illuminator is driven through a plurality of computer controlled polarization sensing horn axial rotational positions at a plurality of discrete positions along said closed travel trajectory azimuth path.

16. Near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus comprising the combination of:

sample mounting apparatus holding a captive sample of said material in selected orientation adjacent focal points of a sample illuminator apparatus and a sample signal receptor apparatus disposed about closed travel trajectory paths;

said sample illuminator apparatus energizing said captive sample from along a first of said travel trajectory paths with spot focused microwave radiant energy of selected wavelength and selected polarization angle;

said sample signal receptor apparatus responsive to reflected and emitted electromagnetic signals received from said sample along a second of said trajectory paths;

selectively energizable electrical driving apparatus moving one of said sample illuminator apparatus and said sample signal receptor apparatus through plural positions along said respective travel trajectory paths while sample determined emissions are collected;

said plural positions along said first and second travel trajectory paths including one of sample reflected and sample refracted output signal trajectory positions determined by one of negative permeability and negative permittivity characteristics in said captive sample;

storing apparatus receiving a sequence of sample determined emissions and trajectory path positions data in response to achieving one of a plurality of differing sample illumination and signal reception positions from along one of said travel trajectory paths;

correlation apparatus examining said storing apparatus data for received signal amplitude and trajectory path angular position relating data characteristic of said near field free space examined materials.

17. The near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus of claim 16 wherein each of said sample illuminator apparatus and said sample signal receptor apparatus is driven along a closed travel trajectory path during operation of said apparatus.

18. The near field, free space, focused microwave energy spot, negative index refractive inclusive material examination apparatus of claim 16 wherein one of said sample illuminator apparatus and said sample signal receptor apparatus is held in fixed position along a closed travel trajectory path during operation of said apparatus.

19. The near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus of claim 16 wherein said sample illuminator apparatus and said sample signal receptor apparatus closed travel trajectory paths are coincident.

20. The near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus of claim 16 further including additional of said electrical driving apparatus moving one of said sample illuminator apparatus and said sample signal receptor apparatus through additional axes defined positions along said respective travel trajectory paths while sample determined emissions are collected.

21. The near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus of claim 16 wherein said selectively energizable electrical driving apparatus further includes rotational driving apparatus connected with one of said sample illuminator apparatus and said sample signal receptor apparatus and controlling horn axis polarization pattern determining rotational position thereof.

22. The near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus of claim 21 wherein said selectively energizable electrical driving apparatus connected with one of said sample illuminator apparatus and said sample signal receptor apparatus is connected with each of said sample illuminator apparatus and said sample signal receptor apparatus disposing each said apparatus in independent, computer controlled, rotational position within a 360 degree azimuthal rotational range.

23. The near field, free space, focused microwave energy spot, negative refractive index inclusive material examination apparatus of claim 16 wherein said storing apparatus is responsive to one of permeability, permittivity and anisotropy characteristic signals received along one of said travel trajectory paths.

24. The near field, free space, focused microwave energy spot, negative index refractive inclusive material examination apparatus of claim 16 wherein said plural positions along said respective travel trajectory paths include both sample reflected and sample refracted output signal trajectory positions determined by one of negative permeability and negative permittivity characteristics in said captive sample.

25. A near field spot microwave energy method of characterizing an anisotropic electromagnetic material comprising the steps of:

illuminating a mounted sample of said anisotropic electromagnetic material from a controllably movable horn antenna source of spot microwave energy;

moving to a plurality of sequentially accessed collection horn antenna azimuth positions disposed in anisotropic signal physical locations and polarization orientations around said mounted sample with a computer driven, collection horn antenna moving apparatus supporting a collection horn antenna;

collecting a plurality of sample determined microwave energy signals during movement to said plurality of sequentially accessed collection of horn antenna azimuth positions;

including in said computer driven, collection horn antenna moving apparatus a plurality of antenna positions and polarization orientations selected to obtain sample determined microwave energy signals to provide at least one of a negative index of refraction, negative permittivity and negative permeability sample determined microwave energy signals; and

determining characteristics of said mounted sample in response to azimuth location, azimuth extent, polarization orientation and amplitude of said negative index of refraction, negative permittivity and negative permeability included sample determined microwave energy signals.

26. The near field spot microwave energy method of characterizing an anisotropic electromagnetic material of claim 25 wherein said plurality of collection horn antenna azimuth positions is performed in closed loop response to polarization orientation, sample negative index of refraction, negative permittivity and negative permeability sample determined microwave energy signals received in said collection horn antenna.

27. The near field spot microwave energy method of characterizing an anisotropic electromagnetic material of claim 25 wherein said plurality of collection horn antenna azimuth positions disposed in anisotropic signal physical locations and polarization orientations around said mounted sample are identified in response to one of polarization orientation, sample negative index of refraction, negative permittivity and negative permeability determined sample microwave energy signals received in said collection horn antenna.