Non-Reciprocal Solid-State Phase Shifter for Radar Cross-Polarization

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Solution Overview

Problem

Existing cross-polarization systems using reciprocal electromechanical phase shifters face challenges with inadequate reciprocity, leading to different phase shifts when transmitting and receiving signals, which affects the accuracy of cross-polarization in systems like monopulse radar tracking circuits.

Innovation Solution

A two-port network utilizing non-reciprocal solid-state phase shifters, where one set of phase shifters is used for signal transmission in one direction and another set for the opposite direction, along with a polarimeter to generate error signals for precise cross-polarization without requiring reciprocal phase shifters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If solid-state phase shifters are used instead of mechanical phase shifters, then switching speed is improved, but reciprocity becomes inadequate leading to different phase shifts in opposite directions

Engineering Contradiction:

Improveswitching speedVSAvoidreciprocity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system divides the phase shifting function into separate reciprocal and non-reciprocal components. The reciprocal hybrid network handles the common phase reference, while the non-reciprocal solid-state phase shifters handle the differential phase control, allowing each component to be optimized independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different types of phase shifters in different locations within the network. Reciprocal phase shifting is implemented in the hybrid network where symmetry is required, while non-reciprocal solid-state phase shifters are used in the signal paths where fast switching is needed, creating local optimization of properties.

Inventive Principle:

Principle #3Local quality

2Speed

If non-reciprocal solid-state phase shifters are used, then switching speed improves, but phase shift accuracy deteriorates with errors of five degrees

Engineering Contradiction:

Improveswitching speedVSAvoidphase shift accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The system incorporates feedback loops that monitor the phase shift output and adjust the control signals to the solid-state phase shifters accordingly. This feedback mechanism compensates for the non-reciprocal characteristics and maintains phase shift accuracy within one degree despite the inherent limitations of non-reciprocal devices.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical phase shifters with solid-state electronic phase shifters, substituting a mechanical system with an electronic one. This substitution enables faster switching speeds while the accompanying electronic feedback control maintains the required precision, overcoming the traditional accuracy limitations of solid-state devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If reciprocal electromechanical phase shifters are used, then phase shift consistency is maintained, but switching speed is insufficient for modern system requirements

Engineering Contradiction:

Improvephase shift consistencyVSAvoidswitching speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9294184B1Accurate fast-switching cross polarization repeater using non-reciprocal solid-state phase shifters

AI summary

In a system for receiving an input signal, for example, at radar frequencies, having polarization components and transmitting an output signal which is cross polarized with respect to an input signal, separate transmit and receive phase shift networks are utilized. Consequently, the phase shift circuitry utilized need not be reciprocal, in order to provide accurate cross polarization.