Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1999-11-04
2001-01-23
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S795000, C343S792500
Reexamination Certificate
active
06177909
ABSTRACT:
CROSS-REFERENCES TO RELATED PATENT APPLICATIONS
None.
BACKGROUND OF THE INVENTION
The present invention relates to antennae, and, in particular, to devices for actively changing the antenna structure.
In the past, microwave antennae have been constructed having a fixed frequency response therein. This fixed response can not be changed to accommodate different operating frequencies. However, many systems, such as aircraft, require antennae operating over multiple frequency bands. Thus, there exists a need for a means of changing an antenna's structure upon command to control the operating frequency of the antenna.
At equilibrium, a semiconductor is semi-insulating, and therefore appears as a dielectric. Illuminating a region of a semiconductor substrate with light of a preselected wavelength results in the generation of free carriers in the substrate and allows the creation of a conductive region (semi-metallic) in the substrate. The generated conductive region can function as an antenna operating over a specific frequency range and with a set radiation pattern. Thus by controlling the pattern of light projected onto the semiconductor substrate, the frequency and radiation pattern of the antennae can be changed.
BRIEF SUMMARY OF THE INVENTION
A reconfigurable photoconductive antenna is created by projecting an image onto a semiconductor substrate. The image is controlled via a digital micromirror device array which is illuminated by a laser source. Based on the photoconductive nature of semiconductors, the areas illuminated by the laser become metallic in nature and form either a single antenna or a phased array antenna comprised of multiple radiating elements. The antenna is reconfigured by electronically driving the digital micromirror device (DMD™) array, which serves as a spatial light modulator. Changing the pattern of the DMD™ array changes the pattern of the reflected light, and thus results in a modification of the antenna pattern. This technique allows the radiating antenna to be modified such that many planar antenna patterns are possible. Example patterns include patch radiators, bow tie antennas, and phased array antennas comprised of multiple radiating elements. The generated antenna pattern is useful in communication and radar systems. Advantages of this new invention include low radar cross section and ultra-wide bandwidth operation.
One object of the present invention is to provide a reconfigurable antenna capable of operating over multiple frequencies. Thus allowing a single antenna to provide the functionality of multiple antennas.
Another object of the present invention is to provide a reconfigurable antenna that optimizes the antenna radiation pattern to a given application.
Another object of the present invention is to provide an antenna capable of being easily and electronically switched between a variety of antenna types including: a log periodic antenna, a bow-tie antenna, or a phased array antenna with multiple radiating elements.
These and many other objects and advantages of the present invention will be apparent to one skilled in the pertinent art from the following detailed description of a preferred embodiment of the invention and the related drawings.
REFERENCES:
patent: 5986796 (1999-11-01), Miles
Larry J. Hornbeck. “Digital Light Processing™ for High-Brightness High-Resolution Applications”, see attached. Feb. 10-12, 1997.
D.W. Liu, P.H. Carr et al “Nonlinear Photoconductivity Characteristics of Antenna Activated by 80-Picosecond Optical Pulses”. see attached. Jun., 1996.
D. Liu, M. Bergeron at al. “Structurally Embedded Photoconductive Silicon Bowtie Antenna” see attached. May 1998.
D.W. Liu, E.E. Crisman et al. “Two and Three Dimensional, Re-configurable Arrays using optical generation as the source-antenna elements”. See attached. Jan. 14, 15, 16, 1997.
X. -C. Zhang and D. H. Auston. “Opticoelectronic measurement of Semiconductor surfaces and interfaces with femtosecond optics.” J. Appl. Phys. 71 (1) Jan. 1992.
Carr Paul H.
Derov John S.
Reid James R.
Auton William G.
Collier Stanton E.
Le Hoang-anh
The United States of America as represented by the Secretary of
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