Communications: radio wave antennas – Antennas – With polarization filter or converter
Reexamination Certificate
2000-01-07
2001-11-06
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With polarization filter or converter
C343S909000
Reexamination Certificate
active
06313803
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to millimeter-wave (MMW) beam steering antennas and more particularly to such antennas which include switching and steering components which along with the antennas can be integrated into a monolithic structure.
BACKGROUND OF THE INVENTION
Electronically-controlled MMW beam-steering antennas the operation of which is based on the interaction of millimeter waves with solid-state plasmas in a planar semiconductor waveguide was disclosed in our paper entitled Monolithic Electronically-Controlled Millimeter-Wave Beam-Steering Antenna. The paper was delivered at the Topical Meeting on Silicon Monolithic Integrated Circuits in R.F. Systems, Sep. 17-18 1998, Ann Arbor, Mich., sponsored by the IEEE Microwave Theory and Techniques Society, NASA Lewis Research Center, Jet Propulsion Laboratory and Army Reserve Office.
The paper describes the need for a beam-steering antenna for a variety of applications such as automobile intelligent control and all-weather aircraft landing and notes that one of the most expensive components of systems suitable for such applications is the beam-steering antenna which performs sensor functions. The existing phased-array technology for electronic beam-steering does not meet the required compactness and cost efficiency criteria. The paper discloses a solid state antenna based on a reconfigurable plasma grating formed in a planar waveguide which performs beam-steering functions at MMW frequencies employing carrier injection to excite the required patterns.
The antenna disclosed in that paper comprises a silicon planar waveguide with an array of two-hundred PIN cells. All the cells have a common bottom ground electrode (N+type) and separate upper electrodes (P+type), the latter controllably connectable to a current source. The activated cells (pixels) are organized to create a periodic pattern of activated pixels which provides a plasma grating which operates as an amplitude deffraction grating for millimeter waves. A dielectric rod waveguide, set at a tunnel distance from the silicon substrate, is used as an antenna feeder.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the principles of this invention an array of parallel, thin metal strips are formed on the surface of a semiconductor substrate to form a metal grid semiconductor structure (MGSS) where the width of each strip is smaller than the wavelength of a wave propagating through the semiconductor substrate and the gap between the strips is smaller than the width of a strip.
The structure has two modes of operation, the first when there are no carriers between strips; the second when the gaps are filled with carriers. In the absence of carriers, the structure is operative as a grid polarizer. When an incident wave has an electric vector parallel to the strips, the wave induces current within the strips. The current generates a secondary wave which interferes with the incident wave resulting in almost total reflection of the incident wave. When the incident wave has an electric vector perpendicular to the strips, due to the small size of the strips in this direction, the current induced by the incident wave is small and the grid has very little affect on the incident wave.
The injection of carriers between the strips provides conductivity in a direction perpendicular to the strips. Any incident wave with any polarization induces current in the strips and is reflected by the structure so long as carriers are present between the strips. The carriers can be injected illustratively, by illumination, by injection from P-and N-electrodes beneath the strips and by using field effects.
If a MGSS is used with a planar dielectric waveguide, a mechanism for phase control is provided where the presence of a conducting imaging surface imposed by an active MGSS changes the mode structure in the waveguide. Mode switching is accompanied by a corresponding change in phase velocity.
The carriers can be injected into the space between metal strips individually to provide a basic element in, for example, a reconfigurable MMW hologram, a controlled reflector, a switch, a phase shifter, as well as a beam steering device.
REFERENCES:
patent: 3628184 (1971-12-01), Thompson
patent: 4079404 (1978-03-01), Comerford
patent: 4867515 (1989-09-01), Normandin
patent: 5323024 (1994-06-01), Adams
patent: 5796881 (1998-08-01), Manasson et al.
patent: 5982334 (1999-11-01), Manasson et al.
Manasson Valadimir
Sadovnik Lev
Chen Shih-Chao
Shapiro Herbert M.
WaveBand Corporation
Wong Don
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