Communications: directive radio wave systems and devices (e.g. – Directive – Including a steerable array
Reexamination Certificate
2001-04-24
2002-09-24
Phan, Dao (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a steerable array
C343S778000
Reexamination Certificate
active
06456236
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to the field of radio and radar applications, and particularly to phased array antennas, such as a ferroelectric/paraelectric/composite material loaded phased array network.
Phased array antennas are required for many radio and radar applications. In the past, cost has been a major impediment to the use of electronically steered phased array antennas. Recent developments in the field of ferroelectric-based phased array antennas have opened new possibilities within the phased array community. Systems that were once cost prohibitive may now be utilized to add/enhance the performance of radio and radar systems.
The use of ferroelectric materials has been of great benefit to phased array antennas. Ferroelectric materials exhibit dielectric properties in which the materials change under the influence of a static electric field. For example, an electrooptic effect may be produced by the application of a bias electric field to ferroelectric materials. Electrooptical variation of the refractive indices of this material causes a phase shift in electromagnetic radiation. For instance, a bias electric field of sufficient magnitude in an appropriate direction may change the refractive index of a medium, and thereby further alter the propagation conditions.
With this new development, new challenges have surfaced. For example, the addition of ferroelectric bulk phase shifters to a planar waveguide phased array antenna can cause space and weight problems. While the bulk phase shifters are capable of performing the job, they add weight, size, and complexity to the antenna.
Therefore, it would be desirable to provide an improved scheme and apparatus for a phased array antenna.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to phased array antennas. The invention allows for the realization of a low-cost, ferroelectric material loaded feed manifold for phase shifting an antenna. This type of architecture can take many forms, with the preferred embodiment being waveguide. This feed manifold can replace the traditional air-filled manifolds currently used on flat-plate antennas. In an embodiment of the present invention, the Ferrolectic/Paraelectric/Composite material loaded feed manifold described herein may solve the space/weight problem by integrating the material into the traditional waveguide feed manifold.
In a first aspect of the present invention, a phase shifting apparatus includes a first guide section and a second guide section. The second guide section is suitable for transmission of electromagnetic radiation and includes material suitable for shifting phase when an electrical field is applied. A first electrode is disposed between the first guide section and the second guide section. A second electrode is positioned opposing the first electrode, in which the second guide section is disposed between the first electrode and the second electrode. The first guide section has an impedance which is at least one of equal to and greater than the second guide section.
In a second aspect of the present invention, a phased array antenna includes a feed structure suitable for receiving and routing electromagnetic energy. The feed structure includes a first guide section and a second guide section including material suitable for shifting phase when an electrical field is applied. A first electrode is disposed between the first guide section and the second guide section. A second electrode is positioned opposing the first electrode, wherein the second guide section is disposed between the first electrode and the second electrode. The first guide section has a dielectric constant at least one of equal to and greater than the second guide section
In a third aspect of the present invention, a phased array antenna includes a feed structure suitable for receiving and routing electromagnetic energy. The feed structure includes a subassembly including material suitable for shifting phase of electromagnetic radiation when an electrical field is applied. A material suitable for blocking a propagating wave from bypassing the subassembly is also included.
In a fourth aspect of the present invention, a feed structure suitable for receiving and routing electromagnetic energy includes a subassembly including material suitable for shifting phase of electromagnetic radiation when an electrical field is applied. Material having a dielectric constant at least one of equal to and greater than the phase shifting material is also included.
It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.
REFERENCES:
patent: 4305052 (1981-12-01), Baril et al.
patent: 5309166 (1994-05-01), Collier et al.
patent: 5334958 (1994-08-01), Babbitt et al.
patent: 5617103 (1997-04-01), Koscica et al.
patent: 6067047 (2000-05-01), Cook et al.
patent: 6333683 (2001-12-01), Hampel
Hauck Bryan L.
West James B.
Eppele Kyle
Jensen Nathan O.
Phan Dao
Rockwell Collins, Inc.
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