Active Retrodirective Antenna Array Virtual Beacon Tracking
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Solution Overview
Problem
Conventional beam tracking in phased array antennas is inefficient and requires significant analog and digital processing to steer a beam towards a target, making automatic beam steering in response to an RF signal problematic.
Innovation Solution
An active retrodirective antenna array (ARAA) uses an optical carrier beam with an RF pilot signal to create a virtual beacon, allowing nodes to phase-conjugate and retransmit the signal back to the target without prior knowledge of the target's location, enabling automatic tracking and coherent beam focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional phased array beam tracking is used to steer a beam towards a target, then the beam direction can be controlled, but significant analog and digital processing is required making the system complex and inefficient
Solution Approach 1:
The retrodirective antenna array automatically steers its transmitted beam towards the apparent source of an incoming pilot signal without requiring external control systems. Each array element self-adjusts its phase shift based on the received signal, eliminating the need for complex centralized processing and control mechanisms.
Solution Approach 2:
Instead of actively steering the beam towards a target using complex processing, the system inverts the approach by having the beam automatically return to the source of an incoming pilot signal. This passive retrodirective approach achieves beam steering through phase conjugation rather than active control.
2Extent of automation
If a physical microwave beacon is attached to a cooperative target for retrodirective operation, then automatic tracking can be achieved, but the system cannot track uncooperative targets without a beacon
Solution Approach 1:
An optical carrier beam is introduced as an intermediary to transfer the pilot signal to uncooperative targets. The optical beam carries the RF pilot signal to the target, and the target's scattered optical beam forms a virtual beacon that enables retrodirective tracking without requiring a physical microwave beacon on the target.
Solution Approach 2:
The system creates a virtual beacon by detecting the scattered optical carrier beam from the target. This virtual beacon replicates the functionality of a physical microwave beacon, allowing the retrodirective array to track uncooperative targets as if they were cooperative with an attached beacon.
3Productivity
If retrodirective arrays are used for microwave power transmission or communication, then efficient directed energy transfer is achieved, but the system requires precise beacon placement and cooperation
Solution Approach 1:
The optical carrier beam serves as a mediator to deliver the pilot signal to uncooperative targets, enabling efficient power transmission and communication without requiring target cooperation or physical beacon attachment. The virtual beacon created from scattered optical light maintains the retrodirective focusing capability.
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 ARAA effectively tracks and returns an amplified RF signal to uncooperative targets, enhancing communication links or enabling directed energy applications by focusing power density on the target, even without a physical beacon, and is more robust than single-source directed-energy weapons.
Implementation Method 1
an optical carrier beam with a first RF pilot signal imposed thereon is directed into a spot on the target
Implementation Method 2
The scattered optical carrier beam forms a virtual beacon
Implementation Method 3
The scattered optical carrier beam is detected by a plurality of the retrodirective array nodes to extract a second RF pilot signal
Implementation Method 4
The phase of the received signal is conjugated with a phase reference derived from the received pilot signal itself
Implementation Method 5
The signals transmitted by the individual nodes converge at the beacon with nearly identical phases, causing them to add coherently
Implementation Method 6
enabling directed energy applications by focusing power density on the target
Data Source
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AI summary
An active retrodirective antenna array is provisioned with a virtual beacon for use with uncooperative targets. An RF pilot signal is imposed onto an optical carrier beam and directed at a target. The scattered optical carrier beam is optically detected by a plurality of the retrodirective array nodes to extract the RF pilot signal. Each recovered RF pilot-signal is phase-conjugated with a phase reference signal, amplified and retransmitted towards the target where the RF beams add-in phase at the virtual beacon. The array may be used to complete an RF communication link with the target, to transfer microwave power from orbiting solar power stations to a target or as a directed energy weapon to prosecute the target.