Sub-diffraction Radar Arrays via Misaligned Beam Overlap

Solution Overview

Problem

Conventional radar systems face limitations in achieving improved angular resolution due to the diffraction limit, which requires either short wavelengths or large transceiver arrays, both of which can be impractical and costly, especially in space-constrained environments.

Innovation Solution

A phased array radar system that transmits multiple slightly misaligned beams from subarrays with different modulations, allowing for improved angular resolution without the need for a large transceiver array, by overlapping beams to create a narrower region of detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the array size is increased to improve angular resolution, then the angular resolution is improved, but the device complexity and cost increase

Engineering Contradiction:

Improveangular resolutionVSAvoidarray size

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The transmitting array is divided into multiple subarrays, each transmitting a separate beam with a different modulation code. This segmentation allows the system to achieve super-resolution by combining signals from multiple subarrays, effectively improving angular resolution without proportionally increasing the total array size.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a temporal dimension through modulation codes assigned to different subarrays. By encoding spatial information from different subarrays with distinct temporal modulation patterns, the system resolves angular information that would otherwise require a larger physical array, effectively adding a time dimension to the spatial measurement problem.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If the array size is increased to improve angular resolution, then the angular resolution is improved, but the cost increases

Engineering Contradiction:

Improveangular resolutionVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The transmitting array is divided into multiple subarrays, each transmitting a separate beam with a different modulation code. This segmentation allows the system to achieve super-resolution by combining signals from multiple subarrays, effectively improving angular resolution without proportionally increasing the total array size.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the modulation parameters (code rate, code length) to optimize the balance between angular resolution and system complexity. By adjusting these parameters, the system can achieve the desired resolution with a practical array size, avoiding the need for excessively large and costly arrays.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the beam width is reduced to improve angular resolution, then the angular resolution is improved, but the signal strength decreases

Engineering Contradiction:

Improveangular resolutionVSAvoidsignal strength

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The patent merges signals from multiple subarrays that each transmit beams with wider individual beam widths. By coherently combining these signals through correlation processing with the assigned modulation codes, the system achieves an effective narrow beam width for angular resolution while maintaining signal strength through the combined energy from all subarrays.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a temporal dimension through modulation codes assigned to different subarrays. By encoding spatial information from different subarrays with distinct temporal modulation patterns, the system resolves angular information that would otherwise require a larger physical array, effectively adding a time dimension to the spatial measurement problem.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This approach enables angular resolution significantly better than the diffraction limit, allowing for precise target location with improved sensitivity and reduced system size and cost.

Implementation Method 1

a phased array radar configured to transmit two or more slightly misaligned beams

Methodology Applied

Scientific EffectPhased Array:

Implementation Method 2

angular resolution at or near the diffraction limit, which is approximately the ratio of the radar wavelength to the size of the transceiver array

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 3

each of which has a different modulation

Methodology Applied

Scientific EffectModulation: Phase Modulation

Data Source

PatentUS9915728B2Sub-diffraction limit resolution radar arrays

Publication Date: 2018.03.13 RAYTHEON CO

AI summary

A phased array radar configured to transmit two or more slightly misaligned beams, for improved angular resolution. The transmitting array is split into two or more subarrays that transmit slightly misaligned beams that may have a common carrier frequency and each of which has a different modulation. Each subarray may include alternate elements in the rows of the transmitting array, and alternate elements in the columns of the transmitting array. The width of each transmitted beam may be greater than or comparable to the diffraction-limited width, but the region in which the beams overlap may be significantly narrower than any of the transmitted beams. The reflected beam from a target contains one or more of the modulations of the transmitted beams, in proportions depending on the location of the target, and the extent to which it is illuminated by each beam.