Waveguide-Fed Cassegrain Antenna for Broadband Impedance Match
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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 with high signal-to-noise ratio and directional gain.
Innovation Solution
A Cassegrain antenna design incorporating a waveguide antenna element with specific radiator patches and substrates within the waveguide body, allowing for a broad frequency band operation by maintaining impedance match and efficient illumination of the sub-reflector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a feed horn or dipole antenna is used as feed antenna, then the Cassegrain antenna can operate at a specific frequency, but the bandwidth over which the feed antenna provides effective feed to sub-reflector is limited
Solution Approach 1:
The feed antenna is segmented into multiple radiator patches (first radiator patch, second radiator patch, third radiator patch) with different dimensions and orientations within the waveguide body. Each patch operates effectively at different frequency ranges, collectively providing broadband operation from 4.9-7.2 GHz while maintaining signal quality through coordinated radiation patterns
Solution Approach 2:
Different regions of the waveguide body contain radiator patches with locally optimized properties - the first radiator patch has specific dimensions for lower frequency operation, the second radiator patch is optimized for mid-frequency, and the third radiator patch handles higher frequencies. Each patch's local characteristics are tailored to its frequency range while collectively providing broadband coverage
2Reliability
If the feed antenna is designed for narrow bandwidth operation, then the signal to noise ratio can be maximized at a specific frequency, but the frequency band over which the Cassegrain antenna operates effectively is limited
Solution Approach 1:
Multiple radiator patches with different frequency optimizations are merged within a single waveguide body structure. The first, second, and third radiator patches are positioned and dimensioned to create overlapping radiation patterns that combine to provide both high signal-to-noise ratio at each frequency and continuous broadband coverage across 4.9-7.2 GHz
Solution Approach 2:
The waveguide body structure serves multiple functions simultaneously: it acts as the feed antenna housing, provides impedance matching across broadband frequencies, supports multiple radiator patches with different characteristics, and maintains proper phase relationships. This multi-functionality enables both high reliability and broad adaptability
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 enables efficient transmission and reception of signals over a broad frequency band, maintaining antenna gain and supporting multiple input multiple output (MIMO) operations with improved signal quality.
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 sub-reflector is used to reflect the signals to or from a primary reflector dish
Implementation Method 3
from which a high gain, narrow beam is formed for transmission or reception from the Cassegrain antenna
Data Source
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 first 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.