Claims
- 1. An antenna comprising
- an ionizing beam generator for directing an ionizing beam along an axis;
- means for energizing said ionizing beam generator thereby to produce a longitudinally extending plasma column along the axis;
- modulating means disposed in the ionizing beam intermediate one end of said ionizing beam generator and the plasma column for modulating the ionizing beam thereby to produce a modulated current in the vertically extending plasma column that radiates electromagnetic energy; and
- reflector means at the other end of said ionizing beam generator for reflecting the modulated current therefrom whereby said antenna operates as a standing wave antenna.
- 2. An antenna as recited in claim 1 wherein said ionizing beam generator comprises a laser.
- 3. An antenna as recited in claim 1 wherein:
- said ionizing beam generator comprises a laser that, when operated by said energizing means, generates a plasma in at least a portion of the column with a concentration of at least 10.sup.12 electrons per cubic centimeter; and
- said reflector means comprises a chamber containing a plasma that has a greater density than the plasma in the plasma column.
- 4. An antenna as recited in claim 3 wherein said reflector means includes means for generating the plasma in said chamber.
- 5. An antenna as recited in claim 4 wherein said reflector means plasma generator comprises a plasma generator taken from the group of laser, electric discharge and radio frequency plasma generators.
- 6. An antenna as recited in claim 5 wherein said reflector means plasma generator comprises a laser and wherein said each of said lasers is taken from the group of CO.sub.2 and Nd:YAG lasers.
- 7. An antenna as recited in claim 3 further comprising a window separating said reflector means plasma from said plasma column.
- 8. An antenna as recited in claim 1 wherein said modulating means comprises:
- means for generating a modulating signal;
- electro-optical crystal means disposed to intercept the laser beam between said laser and said column; and
- a modulator circuit responsive to the modulating signal for energizing said electro-optical crystal means in response thereto whereby said electro-optical crystal means introduces gradients in the plasma that cause charge carriers in the plasma to oscillate parallel to the axis and radiate electromagnetic energy from the antenna, said currents being reflected from said reflector means.
- 9. An antenna as recited in claim 8 additionally comprising means between said modulating means and said reflector means for defining a bounded plasma column.
- 10. An antenna as recited in claim 9 wherein:
- said ionizing beam generator comprises a laser that, when operated by said energizing means, generates a plasma column with a concentration of electrons of at least 10.sup.12 electrons per cubic centimeter in at least a portion of the column; and
- said reflector means comprises a chamber containing a plasma that has a greater density than the plasma in the plasma column.
- 11. An antenna as recited in claim 10 wherein said reflector means includes means for generating the plasma in said chamber.
- 12. A method for radiating electromagnetic energy in response to a signal comprising the steps of;
- directing an ionizing beam along an axis;
- energizing the ionizing beam thereby to produce a longitudinally extending plasma column along the axis having first and second ends thereof;
- modulating the ionizing beam intermediate one end of said plasma column thereby to produce a modulated current in the plasma column that radiates electromagnetic energy; and
- producing a reflecting medium at the second end of the plasma for reflecting the modulated current therefrom whereby the plasma column operates as a standing wave antenna.
- 13. A method as recited in claim 12 wherein said step of direction an ionizing beam includes the step of directing a laser beam along the axis.
- 14. A method as recited in claim 12 wherein:
- said step of directing an ionizing beam includes the step of directing a laser beam along the axis to produce a plasma in at least a portion of the column with a concentration of at least 10.sup.12 electrons per cubic centimeter; and
- said reflection producing step includes the step of locating plasma at the second end of the column that has a greater density than the plasma in the plasma column.
- 15. A method as recited in claim 14 wherein said step of producing the plasma at the second end includes the step of generating the plasma with an ionizing beam produced by a plasma generator taken from the group of laser, electric discharge and radio frequency plasma generators.
- 16. A method as recited in claim 12 wherein said modulating step includes:
- generating a modulating signal;
- interposing an electro-optical crystal means in the ionizing beam to intercept the beam; and
- controlling the electro-optical crystal means in response to the modulating signal whereby the electro-optical crystal means introduces gradients in the plasma that cause charge carriers in the plasma to oscillate parallel to the axis and radiate electromagnetic energy from the antenna, said currents being reflected from the reflecting medium.
- 17. A method as recited in claim 16 additionally comprising the step of enclosing the plasma column.
- 18. A method as recited in claim 17 wherein:
- said steps of directing and energizing an ion beam include energizing a laser to produce a plasma column with a concentration of electrons of at least 10.sup.12 electrons per cubic centimeter in at least a portion of the column; and
- said reflection producing step includes the step of locating plasma at the second end of the column that has a greater density than the plasma in the plasma column.
- 19. A method as recited in claim 18 wherein said reflector means includes means for generating the plasma at said second end.
CROSS REFERENCES TO RELATED PATENT APPLICATION
The instant application is related to two co-pending U.S. Patent Applications entitled PLASMA ANTENNA WITH TWO-FLUID IONIZATION CURRENT (Navy Case No. 78767); and PLASMA ANTENNA WITH ELECTRO-OPTICAL MODULATOR (Navy Case No. 78773) having same filing date.
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5963169 |
Anderson et al. |
Oct 1999 |
|
5990837 |
Norris et al. |
Nov 1999 |
|