Dual-Beam Feed Assembly for Tropospheric Scatter Antennas
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Solution Overview
Problem
Tropospheric scatter communication systems face reliability issues due to signal fades caused by long- and short-term random tropospheric irregularities, which are not effectively addressed by existing diversity techniques, particularly angular diversity, due to performance compromises and high costs associated with dual-feed antenna systems.
Innovation Solution
A dual-beam feed assembly with elongated conical shape feed elements, closely spaced at the focal point of a parabolic reflector, providing non-overlapping beams for angular diversity, allowing for high isolation and efficient signal processing without compromising performance, enabling a cost-effective and transportable tropospheric scatter communication system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If angular diversity is implemented using conventional dual-feed antenna systems, then signal fade reliability is improved, but system cost and complexity increase significantly
Solution Approach 1:
The patent combines two feed horns into a single integrated feed assembly that is collocated at the focal point of the parabolic reflector. This merging of functions allows angular diversity to be achieved without requiring separate dual-feed antenna systems, thereby reducing system complexity while maintaining reliability benefits
Solution Approach 2:
The single feed assembly performs multiple functions: it generates both the first and second beams for angular diversity, provides high isolation between beams through its elongated conical geometry, and maintains efficient signal processing capabilities. This multi-functionality eliminates the need for separate antenna systems for each beam
2Reliability
If two antennas are used for spatial diversity, then signal fade reliability is improved, but system cost, setup time, and footprint increase
Solution Approach 1:
The patent merges the functionality of two separate antennas into a single antenna system with a collocated dual-feed assembly. This consolidation maintains the spatial diversity benefit while dramatically simplifying deployment, reducing the number of antennas from two to one, and decreasing the overall system footprint
Solution Approach 2:
The feed assembly is segmented into two collocated feed horns that are closely spaced, allowing each feed to generate a separate beam for diversity while being integrated into a single antenna structure. This segmentation enables diversity functionality without requiring physically separate antennas
3Reliability
If feed horns are positioned close together for angular diversity, then beam isolation is improved, but coupling loss increases
Solution Approach 1:
The patent changes the geometric parameters of the feed horns by using an elongated conical shape with specific aspect ratios. This parameter change allows the feed horns to be closely spaced for good isolation while the elongated geometry minimizes coupling losses between the closely spaced feeds
Solution Approach 2:
The feed horns have non-uniform cross-sectional dimensions along their length, with the narrower end positioned closer to the reflector. This local quality variation optimizes the balance between beam isolation and coupling loss by concentrating the isolation-critical dimensions at the appropriate location
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 dual-beam feed assembly enhances the reliability of tropospheric scatter communication systems by achieving angular diversity with high isolation between beams, reducing signal fades, and maintaining high antenna gain, making the system more cost-effective and deployable.
Implementation Method 1
Collimated beams are typically created using parabolic-shaped antenna reflectors
Implementation Method 2
The scattering of radio waves off the troposphere, known as tropospheric scatter or troposcatter
Data Source
AI summary
A feed assembly (26) for an antenna system (38) includes a first feed element (30) that propagates a first beam (32) and a second feed element (34) that propagates a second beam (36). The second feed element (34) is collocated with, but displaced vertically from, the first feed element (30) to achieve angular diversity in elevation. Each of the feed elements (30, 34) has an elongated conical shape and is formed from a dielectric material. The feed assembly (26) operates within the Ku-band frequency range to yield high gain, collimated, independent first and second beams (32, 36). The feed assembly (26) can be implemented in a tropospheric scatter communication system (38) in conjunction with a reflector (22) to provide concurrent transmit and receive capability via the two independent, angularly separated first and second beams (32, 36).