Monopulse Tracking Antenna Using Risley Prism Beam Steering
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Solution Overview
Problem
Existing beam steering antennas for monopulse tracking are complex and costly due to the use of active RF components and mechanical gimbals, limiting their efficiency and reliability.
Innovation Solution
A monopulse tracking antenna system utilizing a triple-mode circular waveguide horn, paired with Risley prisms and a parabolic phase correcting surface, enables passive 2-D beam steering by axially rotating dielectric PSSs, eliminating the need for complex feed networks and mechanical gimbals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If electronic steering is used for beam deviation, then scan speed is improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent replaces electronic phase shifters and RF circuitry with a mechanical Risley prism system consisting of two rotating dielectric wedges. This mechanical substitution eliminates complex electronic beamforming networks while achieving electronic-like scan speeds through the rotation of dielectric elements that manipulate electromagnetic wave propagation paths.
Solution Approach 2:
The patent introduces dielectric wedges as intermediary elements between the antenna feed and the radiation pattern. These wedges act as passive beam steering components that manipulate the electromagnetic waves without requiring active electronic control, thereby simplifying the overall system while maintaining fast scanning capability.
2Device complexity
If traditional mechanical steering is used, then device complexity is reduced, but scan speed decreases
Solution Approach 1:
The patent divides the single complex mechanical gimbal system into two independent rotating dielectric wedge elements. Each wedge can rotate independently about the same axis, allowing for simplified mechanical implementation while achieving faster effective scan speeds through the combined action of both elements.
3Adaptability or versatility
If reconfigurable arrays with electronic phase shifters are used for monopulse tracking, then beam steering capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs a single triple-mode waveguide horn that simultaneously generates all three monopulse patterns (sum, azimuth difference, and elevation difference) without requiring separate feed networks or reconfigurable arrays. This universal approach eliminates complex electronic phase shifters while maintaining full monopulse tracking capability.
Solution Approach 2:
The patent replaces the electronic reconfigurable array system with a passive mechanical Risley prism system. The two rotating dielectric wedges provide the necessary beam steering for all three monopulse patterns without requiring any active RF components, thereby simplifying the feed network while preserving adaptability.
4Measurement precision
If a 4-horn feed cluster is used for monopulse patterns, then pattern generation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the functionality of four separate horn antennas into a single triple-mode waveguide horn. This single horn is capable of generating all three monopulse patterns through its ability to support and excite multiple waveguide modes (TE11, TM01, and TE21), thereby reducing structural complexity while maintaining pattern generation accuracy.
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 system achieves efficient, low-cost, and reliable 2-D beam steering for all three monopulse patterns, reducing mechanical complexity and improving scan performance with minimal gain deviation.
Implementation Method 1
beam steering structures inspired from optical Risley prism (RP) concept using dielectric wedges
Implementation Method 2
A typical RP includes two identical phase shifting structures (PSSs) with a linear phase progression along one direction
Implementation Method 3
each Risley prism is coated with an anti-reflective layer
Implementation Method 4
a parabolic phase correcting surface, positioned intermediately between the triple-mode circular waveguide horn and at least two Risley prisms
Data Source
AI summary
A triple-mode monopulse tracking antenna and antenna system with risley prism beam steering. In particular, a monopulse tracking antenna, comprising: a triple-mode circular waveguide horn, configured to generate three monopulse patterns; at least two Risley prisms, each positioned a fixed distance from the triple-mode circular waveguide horn, configured to receive and steer the three monopulse patterns, wherein each Risley prism is coated with an anti-reflective layer; a means for axially rotating each of the at least two Risley prisms; and a parabolic phase correcting surface, positioned intermediately between the triple-mode circular waveguide horn and at least two Risley prisms.