Compact Antenna with Ring Focus Reflector and Feed Network
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Solution Overview
Problem
Existing satellite communication earth station antennas with offset-feed configurations occupy larger volumes due to the placement of the feed network to the side of the reflector, leading to increased radome size and interference concerns, particularly in portable or mobile applications where space and interference minimization are critical.
Innovation Solution
A compact low side lobe antenna design featuring a ring focus reflector with a sub-reflector and stem forming a waveguide structure that directs energy radially outward, utilizing a circular waveguide and annular waveguide sections to minimize side and back lobe radiation, and incorporating a corrugated feed body to concentrate energy and control impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an offset-feed antenna configuration is used to reduce blockage of the reflector aperture, then the feed network can be positioned to one side without blocking the aperture, but the antenna occupies a larger volume and requires a larger radome
Solution Approach 1:
The feed network is repositioned from a lateral offset position to a position above the reflector aperture along the axis, utilizing the vertical dimension rather than lateral displacement. This allows the feed network to clear the aperture plane while maintaining a compact overall antenna volume, resolving the contradiction between aperture area and antenna volume.
2Area of stationary object
If an offset-feed antenna configuration is used to reduce blockage of the reflector aperture, then the feed network can be positioned to one side without blocking the aperture, but side lobe and back lobe radiation increases causing interference
Solution Approach 1:
The feed network structure is modified with localized features including a subreflector with specific curvature, a stem with particular dimensions, and a feed body with corrugations. These local structural qualities are optimized to control the radiation pattern and minimize side lobe and back lobe radiation while maintaining aperture clearance.
3Volume of moving object
If a center-feed antenna configuration is used to minimize antenna volume, then the feed network is located along the axis occupying minimal space, but the feed network blocks a portion of the reflector aperture
Solution Approach 1:
The feed network utilizes the vertical dimension by extending above the reflector aperture plane along the axis, rather than extending laterally. This dimensional repositioning allows the feed network to maintain a compact volume while clearing the aperture area, simultaneously achieving both goals of minimal volume and unblocked aperture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves reduced side lobe and back lobe radiation, allowing for a more compact antenna structure suitable for portable applications while maintaining effective communication within the desired frequency bands, thus addressing the volume and interference issues of traditional offset-feed antennas.
Implementation Method 1
a sub-reflector and stem forming a waveguide structure that directs energy radially outward
Implementation Method 2
incorporating a corrugated feed body to concentrate energy and control impedance matching
Data Source
AI summary
An antenna may include a primary reflector having a ring focus; a feed body along an axis of the primary reflector, the feed body including a circular waveguide coaxial with the axis of the primary reflector; a sub-reflector disposed facing an end of the circular waveguide; and a generally cylindrical stem extending from a center of the sub-reflector into the circular waveguide to form a section of annular waveguide. A sub-reflector support may mechanically connect a perimeter of the sub-reflector and an outside surface of the feed body. The sub-reflector, the stem, and the feed body may be collectively configured to couple microwave energy between the annular waveguide and the primary reflector.