Rotary Traveling Wave Oscillator Array for Phased Radar Coherence

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Solution Overview

Problem

Broadband phased array antenna systems face limitations in maintaining phase coherence across large distances and effectively distributing synchronized signals, leading to reduced antenna gain and inability to combine power from all elements accurately when the aperture exceeds one wavelength.

Innovation Solution

A local oscillator system utilizing a plurality of rotary traveling wave oscillators and phase shifters, arranged in a coherent pattern, provides synchronized local oscillator signals to each antenna element, enabling precise phase control and true-time delay capabilities across the array.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the aperture of the antenna array is increased to improve beam forming capability and directional control, then the ability to form complex beam patterns and nulls is improved, but phase coherence is lost when the aperture exceeds one wavelength

Engineering Contradiction:

Improvebeam pattern control capabilityVSAvoidphase coherence

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The antenna array is divided into multiple sub-arrays, each with its own local oscillator and phase reference. This segmentation allows each sub-array to maintain phase coherence independently while the overall system achieves large aperture capability through coordinated operation of multiple segments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A master oscillator provides a common reference signal that mediates the phase relationship between multiple local oscillators in different sub-arrays. This intermediary reference ensures that all sub-arrays remain phase-coherent with each other, enabling accurate beam forming across the entire large aperture array.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If traditional phase shifters are used to control beam direction, then the system is simpler to implement, but true-time delay capability is lost leading to inaccurate power combination from array elements

Engineering Contradiction:

Improvesignal distribution system complexityVSAvoidpower combination accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

Traditional mechanical or analog phase shifters are replaced with electronically controlled true-time delay circuits. This substitution uses digital or programmable delay elements that can precisely control the time of flight for signals from each antenna element, achieving accurate power combination without the limitations of fixed or coarse phase shifting mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If a single local oscillator is used for the entire antenna array, then the system is simpler, but phase coherence cannot be maintained across large distances

Engineering Contradiction:

Improveoscillator system complexityVSAvoidarray aperture size

Core Design Contradiction:

Device complexityVSLength of stationary object

Solution Approach 1:

The single oscillator system is segmented into multiple local oscillators distributed across different sub-arrays. Each local oscillator is physically located near its corresponding sub-array, reducing the distance over which phase coherence must be maintained and enabling larger overall array apertures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

All local oscillators are synchronized to the same master oscillator frequency and phase reference, creating an equipotential condition where all oscillators operate at the same phase potential. This synchronization ensures that despite physical distribution, all oscillators remain phase-coherent with each other.

Inventive Principle:

Principle #12Equipotentiality

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 solution allows for precise formation and movement of beams, including complex patterns and nulls, and maintains phase coherence over large areas, enhancing the antenna's ability to combine power from all elements, even when the aperture exceeds one wavelength, thereby improving overall antenna performance.

Implementation Method 1

Methodology Applied

Scientific EffectTraveling wave oscillator:

Data Source

PatentUS8629807B2True time delay phase array radar using rotary clocks and electronic delay lines

Publication Date: 2014.01.14 ANALOG DEVICES INC

AI summary

Local oscillator circuitry for an antenna array is disclosed. The circuitry includes an array of rotary traveling wave oscillators which are arranged in a pattern over an area and coupled so as to make them coherent. This provides for a set of phase synchronous local oscillators distributed over a large area. The array also includes a plurality of phase shifters each of which is connected to one of the rotary oscillators to provide a phase shifted local oscillator for the array. The phase shifter optionally includes a cycle counter that is configured to count cycles of the rotary oscillator to which it is connected and control circuitry that is then operative to provide a shifted rotary oscillator output based on the count from the cycle counter.