Planar scanner antenna for high frequency scanning and radar environments

A planar scanning antenna is configured for scanning and tracking. In one embodiment, the planar scanning antenna may include a transducer module configured to provide an electromagnetic beam. According to another aspect of the invention, the apparatus may include a first planar dielectric element having an axis of rotation and configured to direct an electromagnetic beam. In one embodiment, a second planar dielectric element oriented adjacent to the first planar dielectric element and having the axis of rotation may be configured to direct electromagnetic energy. The apparatus may further include a mounting structure arranging the transducer module and the first and second planar dielectric elements. In yet another embodiment, the apparatus may include a drive means for positioning the first planar dielectric element independently from the second planar dielectric element.

FIELD OF THE INVENTION

The present invention relates in general to antennas for scanning and radar applications, and more particularly to a planar scanner configured to utilize one or more planar dielectric elements arranged with an antenna to provide conical scanning.

BACKGROUND

Scanning antennas have been used for communication and radar systems utilizing conical scanning and tracking techniques. Conventional scanning techniques utilize beam steering through switching of antenna elements or by changing the relative phases of the radio frequency signal driving the elements. However, conventional antenna systems are not well suited to meet the demands of current requirements. Typical scanning antennas require an enormous number of electronically controlled active elements, yielding designs with increased complexity and enormous development costs. Such antennas systems are vulnerable to lens loss, interface matching, drive motor speed and control. In addition, applications of such antenna systems are limited by physical requirements imposed on the antenna design.

While conventional antenna structures provide conical scanning and tracking, antenna requirements do not suit applications limiting the geometry and complexity of the antenna design. Accordingly, there is a need in the art for an improved planar scanning antenna design.

BRIEF SUMMARY OF THE INVENTION

Disclosed and claimed herein is an apparatus for a planar scanning antenna. In one embodiment, the apparatus includes a transducer module configured to provide an electromagnetic beam. The apparatus may further include a first planar dielectric element having an axis of rotation and configured to direct an electromagnetic beam, as well as a second planar dielectric element oriented adjacent to the first planar dielectric element and also having the axis of rotation and configured to direct electromagnetic energy. The apparatus may further include a mounting structure arranging the transducer module, the first planar dielectric element and second planar dielectric element. According to another embodiment of the invention, the apparatus includes a drive means for positioning the first planar dielectric element independently from said second planar dielectric element.

Other aspects, features, and techniques of the invention will be apparent to one skilled in the relevant art in view of the following detailed description of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

One aspect of the invention is to provide a planar scanning antenna having a compact structure applicable to scanning and tracking applications. In one embodiment, a planar scanning antenna may include a transducer module, a first planar dielectric element, a second planar dielectric element and a mounting structure, wherein the transducer module first and second planar dielectric elements and a drive means are arranged by the mounting structure. The transducer module may be configured to provide an electromagnetic beam. According to another embodiment of the invention, the first planar dielectric element may have an axis of rotation normal to the transducer module and further configured to direct said electromagnetic beam. The second planar dielectric element may be oriented adjacent to the first planar dielectric element having the same axis of rotation, and configured to direct electromagnetic energy.

According to another embodiment of the invention, planar dielectric elements may be configured to impart a phase shift on incident electromagnetic energy applied to the elements. A drive means may be used to provide positioning of the first planar dielectric element independently from said second planar dielectric element. Similarly a transducer module may also be configured to provide a collimated beam source from one of a slotted array, a parabolic reflector, a micropatch array, horn assembly and horn array.

Another aspect of the invention is to provide a mounting structure for a planar scanning antenna of the invention. The mounting structure may be configured to provide independent rotation of a plurality planar dielectric elements arranged by the mounting structure. The mounting structure may include inner and outer tubes configured to be coupled to a first and second planar dielectric elements respectively. In certain embodiments, the mounting structure may further be provided for coupling a transducer module and associated feed horn, and be configured as a cylindrical package providing flush mounting to a planar structure.

With respect to a flush mounted embodiment, it can be appreciated that the antenna may be configured to be mounted to a structure such that the scanning aperture is flush with the surrounding structural surface. According to an additional embodiment of the invention, the scanning antenna may be implemented in one or more of a shipboard structure, vehicle structure and communications structure.

Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment” or similar term means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of such phrases or in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner on one or more embodiments without limitation.

Referring now toFIG. 1, depicted is one embodiment of an antenna structure100configured in accordance with the principles of the invention. As shown, antenna structure100includes a first planar dielectric element105and a second planar dielectric element110. First and second planar dielectric elements105and110, may be configured to independently impart a phase shift on electromagnetic energy applied to the elements. It may be appreciated that the first and second planar dielectric elements includes any combination of a lens, dielectric wedges and phase-directing surfaces. In one embodiment, planar dielectric elements105and110may further comprise one of a stepped lens and constrained lens.

Continuing to refer toFIG. 1, antenna structure100may also include a drive means115, electromagnetic loading structure120, spacer125and sub-reflector130. In one embodiment of the invention, the antenna structure100may be configured to provide a collimated beam of electromagnetic energy in a fixed direction. To that end, electromagnetic loading structure120, spacer125and sub-reflector130may be configured to generate such a collimated beam. Antenna structure100may further include so-called Flat Parabolic Surface (FLAPS) technology surface101as generally described in U.S. Pat. No. 4,905,014 to Gonzalez et al., as shown inFIG. 1. According to another aspect of the invention, antenna structure100may include a slotted array, parabolic reflector, patch array, micropatch array and/or cassegrain type configuration reflector, such as a twist cassegrain configuration reflector101, as shown inFIG. 1. According to a further embodiment of the invention, spacer125may be one or more of a foam material, dielectric material and air gap.

With respect to the drive means115, independent rotation of planar dielectric elements105and110may be provided for steering of electromagnetic energy. In one embodiment of the invention, the drive means may be provided by a motor. Tube assembly135may be configured to couple planar dielectric elements105and110to drive means115such that planar dielectric elements105and110may be rotated continuously about an axis normal to a major surface of the elements. According to another embodiment, drive means may be configured to rotate planar dielectric elements105and110at one or more of a constant speed and variable speeds. It may further be appreciated drive means may rotate each of the planar dielectric elements105and110at respective speeds and directions. Similarly, drive means may rotate planar dielectric elements105and110to at least one desired position and hold the elements at the desired position for a period of time. It should further be appreciated that antenna structure100may be configured to provide a continuous scan over a conical region of ±45 degrees about the antenna structure100normal.

Referring now toFIG. 2, a mounting structure200is depicted according to one embodiment of the invention. As shown, the mounting structure200may include support for a first planar dielectric element205, support for a second first planar dielectric element210, mount215, lens coupling220, inner drive tube225and outer drive tube230. The first and second planar dielectric elements205and210may be coupled to inner drive tube225and outer drive tube225, respectively. In one embodiment, a planar dielectric element (e.g., first planar dielectric element210) may be coupled to a drive tube (e.g., outer drive tube230) by coupling220. Coupling may be provided by a bonded assembly in one embodiment of the invention. In another embodiment of the invention, drives means (e.g., drive means115) may be coupled to mount215and may provide independent rotation of planar dielectric elements205and210. Mounting structure may include planar dielectric elements205and210which are rotatable about an axis normal to a major surface of the elements. Mounting structure200may be further configured to support one of more of a feedhom (not shown) and spacer125. In one embodiment, mounting structure200may be further configured to provide an air gap.

Referring now toFIG. 3, a disassembled view is depicted of planar scanning antenna300, according to one embodiment of the invention. As shown, planar scanning antenna300may include motor305, collimating surface310, sub-reflector315, a first planar dielectric element330and second planar dielectric element335. Sub-reflector315may be coupled to collimating surface310as shown to provide a collimated beam source. Collimating surface310and sub-reflector315may then coupled to motor305. First planar dielectric element330and second planar dielectric element335may be coupled to inner drive tube320and outer drive tube325respectively. Planar scanning antenna300may be assembled through coupling of inner drive tube320with first planar dielectric element330to motor305and concentrically overlying outer drive tube325with first planar dielectric element335to motor305.

Referring now toFIG. 4, a transducer module400is depicted according to one or more embodiments of the invention. In one embodiment, transducer module400may include electromagnetic loading surface405, sub-reflector410and feedhom415. In one embodiment, feedhom415may provide electromagnetic energy which may be applied to the electromagnetic loading surface405and sub-reflector410so as to provide a collimated beam of electromagnetic energy420of a particular frequency. It should be appreciated that transducer module400may be configured to be operable within various frequency ranges. By one example, transducer module400may be configured to be operable in the microwave frequency band.

Electromagnetic loading surface405may be separated from sub-reflector410by a distance425. In one embodiment, insulating foam (e.g., spacer125ofFIG. 1) may be provided between the electromagnetic loading surface405and sub-reflector410. According to another aspect of the invention, electromagnetic loading surface405may have a dimension430to meet requirements of a prescribed system. As such, for scanning and radar applications, sub-reflector410and distance425may correspond to at least one of an operational frequency range and size limitations imposed by a mounting structure. Distance425and length430may be set to provide a desired operation. In one embodiment, distance425may be on the order of 2.5 inches, while length430of the loading surface405may be 5 inches. It may further be appreciated that distance425and length430may be provided such that to be within ⅓ to ⅔ the focal distance of the reflector.

Referring now toFIG. 5, a graphical representation of antenna scan pattern500is depicted according to one embodiment of the invention. Collimated beam source (e.g., transducer module400) may be applied to a first dielectric element (e.g., first planar dielectric element105), wherein a scan pattern may be generated with a beam peak corresponding to locus505as the first dielectric element is rotated. According to another embodiment, rotating a second dielectric element (e.g., second planar dielectric element110) arranged in front of the fixed first dielectric element may generate scan pattern510. In this fashion, by independently rotating the first and second dielectric elements arranged in front of a collimated beam source, an overall scan pattern515may be obtained. It should be appreciated that a planar scanning antenna according to one of more embodiments of the invention may be configured to provide scanning to any point within scan pattern515. In certain embodiments, antenna scan pattern515may be described by the linear addition of the sine of two planar dielectric refraction angles corresponding to the first and second planar dielectric elements as characterized by the following:
(sin(θmax))=sin(θelement 1)+sin(θelement 2))where,θelement 1=angular offset imparted by the first planar dielectric element,θelement 2=angular offset imparted by the second planar dielectric element,θmax=resultant angular offset.
According to an additional embodiment of the invention, scanning may be provided at any point within antenna scan pattern515on the order of fractions of a second.

Referring now toFIG. 6, a graphical representation600of planar scanning antenna beam strength610is depicted according to one embodiment of the invention. Graphical representation600provides a rectangular plot of relative power in decibels (dB) with respect to antenna azimuth degree. Planar scanning antenna beam strength610may be generated by collimated beam source (e.g., transducer module400).

Referring now toFIGS. 7A-C, graphical representations of antenna scan patterns are provided according to one or more embodiments of the invention.FIG. 7Adepicts a graphical representation700which plots relative power (dB) with respect to antenna azimuth degree. In one embodiment, antenna scan pattern710results by rotating first and second dielectric elements (e.g., first and second planar dielectric element105and110) such that a scanning beam may be directed −10 degrees from an axis normal to the planar scanning antenna.

Referring now toFIG. 7B, graphical representation720provides antenna scan pattern730according to one embodiment of the invention. Antenna scan pattern730may be provided by rotating first and second dielectric elements (e.g., first and second planar dielectric element105and110) such that a scanning beam may be directed −30 degrees from an axis normal to the planar scanning antenna. Referring now toFIG. 7C, graphical representation740provides antenna scan pattern750according to one embodiment of the invention. In one embodiment, antenna scan pattern750may be provided by rotating first and second dielectric elements (e.g., first and second planar dielectric element105and110) such that a scanning beam may be directed +33 from an axis normal to the planar scanning antenna. It should further be appreciated that antenna structure of one embodiment of the invention may be configured to provide a continuous scan over a conical region of ±45 degrees about the antenna structure normal.

Referring now toFIG. 8, system800is provided for a flush mounting application of a planar scanning antenna (i.e., antenna structure100) to surfaces or a prescribed geometry. Antenna requirements for shipboard applications requiring antennas to be placed flush with ship super structure815of the ship820may be satisfied by a planar scanning antenna configured in accordance with principles of the invention (e.g., antenna structure100). In one embodiment of the invention, a scanning aperture805of a planar scanning antenna (e.g., antenna structure100) may be flush mountable to surface super structure815. According to another aspect of the invention, drive means810may be flush mountable to surface super structure815. It may further be appreciated that planar scanning antenna, according to one or more embodiments of the invention, may be configured to conform to various surfaces.

While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art. Trademarks and copyrights referred to herein are the property of their respective owners.