Patent Application
20140254976
1. Field of the Invention
This invention relates to equipment useful in high frequency radio communications systems. More particularly, the invention is concerned with a polarization rotator for changing the polarization of signals passing through a waveguide.
2. Description of Related Art
Rotator elements placed in-line with a waveguide are useful for changing the polarization of a signal prior to further processing. Waveguides associated with antennas may include polarization rotation functionality, for example, to allow conversion of the antenna between horizontal and vertical polarization, without requiring rotation of the entire antenna assembly.
The geometries of in-line polarization rotation elements are well known in the art. Transition elements inserted into the electrical signal path progressively rotate the signal through a desired angular rotation, such as ninety degrees between “vertical” and “horizontal” polarization or vice versa. The transition elements may be provided as a plurality of plates, layers or the like. However, these additional elements increase the total number of parts, complicating manufacture. Further, the plurality of layers may introduce alignment and/or signal leakage issues between each of the several plates/layers.
Alternatively, the transition elements may be applied as a plurality of pins extending across the waveguide. However, insertion and sealing of each pin end at the waveguide sidewalls may be labor-intensive. U.S. Pat. No. 2,628,278 “Apparatus for Rotating Microwave Energy” issued 20 Sep. 1951 to J. F. Zaleski discloses an adjustable circular waveguide polarization rotator that utilizes a twisted septum element suspended within a waveguide by pins at each end coupled to sidewalls of two rotatable body portions of the waveguide. By twisting the body portions with respect to each other, the septum is twisted to obtain a desired polarization angle transition. Although the required number of sidewall pin interconnections is reduced, the thin septum element suspended between the pins may be susceptible to vibration, sagging and/or other forms of distortion over time.
Depending upon the equipment combination used, a waveguide cross-section transition between, for example, a circular to rectangular waveguide may also be required as a further additional component located, for example, between an antenna and a transmitter or receiver.
Competition within the waveguide and RF equipment industries has focused attention upon improving electrical performance, reduction of the number of overall unique components, as well as reductions of manufacturing, installation and or configuration costs.
Therefore, it is an object of the invention to provide an apparatus that overcomes deficiencies in the prior art.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, where like reference numbers in the drawing figures refer to the same feature or element and may not be described in detail for every drawing figure in which they appear and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
The inventors have recognized that, when care is taken to avoid overhanging edges, a polarization rotator with a twist septum may be cost efficiently manufactured with a high level of precision by injection molding, casting or the like, reducing alignment and or sealing issues associated with multiple layer polarization rotation assemblies. Further, in applications in which a high density array of polarization rotators is required, prior issues with access to individual sidewalls, for example for applying through sidewall pin interconnections or the like may be eliminated.
As shown for example in
One skilled in the art will appreciate that diametral, as applied herein, is defined as a straight line segment passing through the center of a figure, such as a circle or rectangle (including a square). The twist of the diametral septum 15 changes the location of the intersections with the sidewall 20 of the line segment at successive longitudinal locations along the diametral septum 15, but the line segment always passes through the center, resulting in a helical characteristic of the diametral septum 15. Further, “unitary”, as applied herein, is defined as describing the body as a single contiguous portion of homogeneous material. Therefore, a unitary body 5 and diametral septum 15 thereof would not be the result of integrating separate sub-elements by welding, soldering, gluing or the like.
One skilled in the art will appreciate that the bore 10 may be provided with a circular cross-section, as best demonstrated in
The waveguide polarization rotator 1 may be configured in a matrix configuration, for example as shown in
One skilled in the art will appreciate that the waveguide polarization rotator 1 may be cost effectively manufactured by molding and/or casting processes, such as polymer material injection molding or metallic material casting. When polymer material injection molding is applied, a conductive polymer may be applied or an additional step of metalizing at least the bore and septum areas of the unitary body 5 may be performed.
As best demonstrated in
Where the desired polarization twist angles would require a bore longitudinal extent that renders mold separation difficult, multiple complementary unitary bodies 10 may be stacked upon each other, the bores 10 of each aligned along their longitudinal axis to obtain the desired final twist angle. Alternatively, for minimization of the required longitudinal extent of the unitary body 5, the twist angle obtained may be reduced and additional twist obtained by applying a parallel grid 55 to the unitary body, for example as demonstrated by
The insertion loss of the twist septum polarization rotator 1 may be very low, even if the septum 15 is shortened, as demonstrated in
One skilled in the art will also appreciate that the benefit of a parallel grid 55 is not limited to a twist septum type polarization rotator 1. The parallel grid 55 may be coupled with any form of waveguide polarization rotator to obtain the benefits of cross-polar signal suppression and/or reduced overall length of the polarization rotator.
One skilled in the art will further appreciate that the flat panel antenna is a particularly useful application for the matrix of waveguide polarization rotators 1 as a 45 degree twist as demonstrated in
From the foregoing, it will be apparent that the present invention may bring to the art a high performance waveguide polarization rotator particularly suited for high density matrix configuration and/or cost efficient manufacture by molding or casting with a very high level of precision.
Where in the foregoing description reference has been made to materials, ratios, integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus, methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicant's general inventive concept. Further, it is to be appreciated that improvements and/or modifications may be made thereto without departing from the scope or spirit of the present invention as defined by the following claims.
