Dual Mode Seeker RF IR Sensor Integration
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Solution Overview
Problem
Existing anti-radiation missiles (ARMs) face challenges in effectively guiding towards targets under varying radar frequency conditions and polarization senses, and lack an alternate guidance mechanism when jamming signals cease, rendering them ineffective.
Innovation Solution
A dual mode seeker system that combines infrared and radio frequency sensors, sharing a common boresight axis, allowing for seamless handover between modes, and includes a toroidal array of orthogonally disposed antenna elements to receive radio frequency energy over a wide frequency band and convert signals for guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-radiation missile uses a radio frequency seeker to home in on radar radiation from ground defense systems, then the missile can effectively track and attack radar-emitting targets, but the missile becomes ineffective when the target ceases transmitting jamming signals
Solution Approach 1:
The seeker is designed to perform multiple functions by incorporating both radio frequency reception capabilities and infrared detection capabilities. The same optical axis and sensor platform are used for both RF signal acquisition and IR target detection, allowing the missile to effectively track targets whether they are emitting radar signals or not, thus resolving the contradiction between reliability in tracking and adaptability to target behavior changes
2Ease of operation
If the seeker uses a single optical axis for both infrared and radio frequency sensors, then the handover between modes is facilitated, but the device complexity increases due to integrating multiple sensor systems
Solution Approach 1:
The patent merges the infrared sensor system and radio frequency sensor system into a single integrated platform sharing a common optical axis. The RF antenna elements are positioned around the infrared optics, and both sensors are mounted on the same gimbal assembly, allowing seamless mode handover while managing complexity through unified mechanical support and alignment mechanisms
3Adaptability or versatility
If the radio frequency receiver operates over greater than an octave band of frequencies, then the seeker can respond to radar signals with different polarization senses and frequencies, but the device complexity and signal processing requirements increase
Solution Approach 1:
The radio frequency receiver is segmented into multiple orthogonally disposed antenna elements arranged in a toroidal array around the optical axis. Each antenna element can be independently controlled and processed, allowing the system to handle different frequencies and polarization senses by selectively activating and processing signals from specific antenna segments, thus managing the complexity of wideband operation
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
Enables effective tracking and guidance of anti-radiation missiles across a broad frequency band and multiple polarization senses, ensuring target acquisition even when primary guidance mechanisms fail, such as during jamming cessation.
Implementation Method 1
the focusing means includes a folded optical arrangement made up of a primary and a secondary reflector
Implementation Method 2
the dispersing means includes a light pipe
Implementation Method 3
a photodetector; means disposed between the image plane and photodetector for dispersing the infrared radiation on the face of the photodetector
Implementation Method 4
means, mounted behind and sharing a common aperture with the infrared focusing means, for receiving radio frequency energy over greater than an octave band of frequencies; means, integral with the receiving means, for converting radio frequency signals to a suitable intermediate frequency (I.F.)
Data Source
AI summary
A dual mode R.F./IR seeker suitable for use in an anti-radiation missile is disclosed. The infrared sensor is responsive to radiation within the 4.0 to 4.8 micron band and the radio frequency sensor is responsive to radio frequency signals within a 6.5 to 16.5 GHz band. The infrared sensor comprises a folded Cassegrainian telescope arrangement, including a primary mirror which is transparent to radio frequency energy. The radio frequency sensor comprises an annular array of orthogonally disposed stripline flared notch radiating elements. A broadband microwave receiver, fabricated in a multilayered stripline package, is provided for forming radio frequency monopulse sum (Σ) and difference (Δ) signals and for converting such radio frequency monopulse signals to suitable intermediate frequency signals for processing in an I.F. receiver. The infrared and radio frequency sensors share a common aperture and optical axis.