Steerable Antenna With Fixed Actuators and Dual-Axis Reflector
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Solution Overview
Problem
Steerable antennas for wide scan angles face challenges with the 'key-hole effect' or singularity at nadir, requiring high-speed actuators and complex drive electronics, and existing solutions either eliminate rotary joints with additional weight and complexity or retain them with limited pointing range and cost issues.
Innovation Solution
A steerable antenna configuration with fixed rotary actuators on a stationary support structure, eliminating the need for RF rotary joints and movable harnesses, allowing beam steering over a full hemisphere without singularities, using a reflector assembly with perpendicular axes of rotation and a gear assembly for smooth movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rotary joints are eliminated to reduce signal loss and improve reliability, then reliability is improved, but device complexity increases due to alternative mechanisms required
Solution Approach 1:
The patent removes rotary joints from the antenna system entirely, extracting the problematic component that caused signal loss and reliability issues. Instead of using traditional rotary joints to enable rotation, the invention uses a fixed feed horn with a reflector assembly that rotates without requiring signal-carrying rotary connections.
Solution Approach 2:
The patent replaces the mechanical RF rotary joint system with a purely mechanical rotation system for the reflector assembly. The feed horn remains stationary while the reflector rotates mechanically, eliminating the need for rotary joints that combine mechanical rotation with RF signal transmission.
2Adaptability or versatility
If nadir-pointing azimuth rotation axis is used for wide scan coverage, then coverage area is improved, but key-hole effect occurs causing tracking failure near singularity
Solution Approach 1:
The patent employs asymmetric positioning of the feed horn relative to the rotation axis, placing it off-axis to eliminate the singularity problem. This asymmetric configuration ensures that the reflector never needs to point exactly at nadir, avoiding the key-hole effect while maintaining wide scan coverage capability.
Solution Approach 2:
The patent introduces a secondary rotation axis perpendicular to the primary azimuth axis, adding a dimensional degree of freedom. This dual-axis rotation system allows the reflector to achieve wide scan coverage without relying on nadir-pointing, thereby eliminating the singularity issue associated with single-axis nadir-pointing systems.
3Productivity
If high-speed actuators are used to overcome key-hole effect, then target tracking is improved, but device complexity and cost increase
Solution Approach 1:
The patent prevents the key-hole effect from occurring in the first place by using asymmetric feed horn positioning and dual-axis rotation, rather than trying to compensate for it with high-speed actuators. This preliminary design approach eliminates the need for excessive actuator speed while maintaining tracking capability.
Solution Approach 2:
Instead of using high-speed actuators to overcome the singularity problem, the patent inverts the approach by designing a system where the singularity never occurs. The asymmetric configuration and dual-axis rotation work together to eliminate the need for high-speed compensation, reducing actuator complexity and cost.
4Ease of operation
If RF rotary joints are retained for axis rotation, then ease of operation is maintained, but signal loss and cost increase
Solution Approach 1:
The patent removes RF rotary joints from the system, extracting the component that causes signal loss. The stationary feed horn eliminates the need for RF signals to pass through rotating joints, thereby eliminating the associated signal attenuation and cost.
Data Source
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AI summary
A steerable antenna configuration (10) having all actuators (28, 30) and the feed source (16) mounted on a stationary side of the antenna thereby eliminating the need of having to supply power and/or communication signal through a rotation mechanism. A first actuator (28) rotates a reflector assembly (22) about a first axis (24), and a second actuator (30) rotates at least a main reflector (32) of the reflector assembly (22) about a second axis (26) perpendicular to the first axis (24). The second axis (26) is rotatable about the first axis (24) via the first actuator (28).