Waveguide Patch Feed for Broadband Cassegrain Antennas
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Solution Overview
Problem
Cassegrain antennas face limitations in bandwidth due to the restricted frequency band over which the feed antenna effectively operates, limiting their ability to transmit and receive signals at high signal-to-noise ratio.
Innovation Solution
A Cassegrain antenna design incorporating a waveguide antenna element with specific radiator patches and substrate configurations within the waveguide body, allowing for a broad frequency band operation and efficient impedance matching, enabling transmission and reception over a range such as 4.9-7.2 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a feed horn or dipole antenna is used as feed antenna, then the structure is simple and easy to manufacture, but the bandwidth over which the feed antenna provides an effective feed to sub-reflector is limited
Solution Approach 1:
The feed antenna is segmented into multiple radiator patches (first and second patches) with different orientations and dimensions, each contributing to different frequency ranges. This segmentation allows the overall antenna to operate effectively across a broader bandwidth while maintaining a relatively simple waveguide body structure that is easy to manufacture.
Solution Approach 2:
Different regions of the waveguide body contain radiator patches with locally optimized properties - the first radiator patch has specific dimensions and orientation for certain frequency ranges, while the second radiator patch has different dimensions and orientation for other frequency ranges. This local quality variation enables broadband operation without complicating the overall manufacturing process.
2Volume of moving object
If a conventional feed antenna is used, then the structure is compact, but the frequency band over which the antenna operates effectively is limited
Solution Approach 1:
Multiple radiator patches with different electrical characteristics are merged within a single waveguide body structure. The first and second radiator patches are positioned at different locations and orientations within the same compact waveguide, allowing the antenna to operate across a wide frequency band while maintaining a compact overall volume.
Solution Approach 2:
The radiator patches are arranged in different spatial dimensions within the waveguide body - different positions, orientations, and depths. This multi-dimensional arrangement allows each patch to contribute to different frequency ranges, expanding the operational bandwidth without increasing the external volume of the feed antenna.
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 broadband impedance matching and maintains antenna gain across a wide frequency band, supporting multiple input multiple output (MIMO) operations and improved signal illumination of the sub-reflector.
Implementation Method 1
a first waveguide antenna element disposed as a feed for the sub-reflector, wherein the waveguide antenna element comprises: a waveguide body having a conductive back plate electrically connected to the waveguide body; a first radiator patch; a second radiator patch
Implementation Method 2
The arrangement of patches gives a broad impedance match into the waveguide body for signals transmitted to or from the feed tracks
Implementation Method 3
a first planar substrate carrying a ground plane, wherein the first radiator patch, the second radiator patch and the first planar substrate are disposed within the waveguide body and substantially parallel to the conductive back plate of the waveguide body, the ground plane comprises a slot on a first side
Data Source
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AI summary
A Cassegrain antenna comprises a primary reflector dish, a sub-reflector and a first waveguide antenna element disposed as a feed for the sub-reflector. The waveguide antenna element comprises a waveguide body having a conductive back plate electrically connected to the waveguide body, a first radiator patch, a second radiator patch, and a first planar substrate carrying a ground plane. The first radiator patch, the second radiator patch and the first planar substrate are disposed within the waveguide body and substantially parallel to the conductive back plate. The ground plane comprises a slot on a first side, the first side being disposed towards the second radiator patch, and the first planar substrate carries a feed track corresponding to the slot on an opposite side of the first planar substrate to the side carrying the ground plane.