Wideband Wave Rotation Using DFT Array Weighting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current technologies cannot effectively rotate or shape far field wavefronts over a wideband frequency range, limiting their application in systems like RF and acoustic arrays, particularly for evading missile and torpedo detection systems.
Innovation Solution
The use of Discrete Fourier Transform (DFT) to compute array weights independently for each frequency bin, allowing for the rotation or shaping of waves across nearly any desired signal bandwidth, extending the Wave Mechanics technique from narrowband to wideband signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional narrowband signal models are used for wave rotation or shaping, then the wavefront manipulation is effective at a single frequency, but the capability is lost across wideband frequency ranges
Solution Approach 1:
The wideband signal is segmented into multiple narrowband frequency bins using Discrete Fourier Transform (DFT). Array weights are independently computed for each frequency bin to maintain consistent wave rotation across the entire wideband range. This segmentation allows frequency-specific optimization while preserving overall wideband performance.
Solution Approach 2:
The invention changes the parameter of array weights from being frequency-independent (narrowband) to frequency-dependent (wideband). By computing distinct weight sets for different frequency bins and then inverse transforming to time domain, the system achieves wideband wave rotation with consistent angular deviation across all frequencies.
2Reliability
If independent frequency bin weighting is implemented for wideband signals, then wave rotation consistency across frequency is achieved, but computational complexity increases
Solution Approach 1:
The invention extracts the frequency-dependent characteristics from the wideband signal by applying DFT to separate it into discrete frequency bins. This allows independent weight optimization for each bin while maintaining the overall wideband signal structure through inverse transformation, achieving consistency without requiring complete system redesign.
Solution Approach 2:
The patent replaces traditional mechanical or hardware-based frequency tuning mechanisms with digital signal processing operations. By using DFT and inverse DFT in the digital domain to compute and apply frequency-specific weights, the system achieves wideband wave rotation with reduced hardware complexity and increased flexibility.
3Adaptability or versatility
If far field wavefronts are manipulated to be non-orthogonal to propagation direction, then wave rotation capability is achieved, but the traditional orthogonal wavefront assumption is violated
Solution Approach 1:
The invention performs preliminary computation of array weights for each frequency bin before actual signal transmission. By pre-calculating the frequency-dependent weights that produce the desired non-orthogonal wavefronts, the system achieves complex wave shaping without real-time computational burden during signal generation.
Solution Approach 2:
The patent introduces the Discrete Fourier Transform as an intermediary that bridges the time domain signal and the frequency domain weight computation. This intermediary allows the system to manipulate wavefronts in the frequency domain and then transform back to time domain, simplifying the implementation of non-orthogonal wavefront shaping.
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 consistent wave rotation or shaping across a wide frequency range, effectively misleading detection systems by creating rotated wavefronts that appear as a controlled and directed wave, enhancing the capability to deceive missile and torpedo tracking systems.
Implementation Method 1
the magnitude and phase of a relationship resulting from the weighted sum of some or all array elements, are employed to derive a pre-determined value for the wave magnitude and phase
Data Source
AI summary
In patent application Ser. No. 15,934563, a method was developed that achieves wave rotation or shaping in the near field and far field, for narrowband RF Signals. That is, using an acoustic or RF phased array, the effective wavefront can be rotated from the propagation normal, at a selected location region in space. In this innovation, the application has been extended to Wideband Signals, where the signal bandwidths can highly exceed the one-percent of carrier frequency narrowband threshold.