Radar Receiving Circuit Protection via Moving Object Detection

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Solution Overview

Problem

Conventional radar devices face the risk of receiving circuit damage due to excessive reflected power from objects with large radar cross-sections, particularly in the millimeter waveband, where the use of power attenuators increases noise figure and compromises detection sensitivity.

Innovation Solution

A radar system with a determination unit and controller that temporarily stops radar operation when a moving object is detected, preventing excessive reflected power from entering the receiving circuit without using power attenuators, thereby protecting the circuit and maintaining detection sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a power attenuator is arranged in front of the receiving circuit to prevent excessive power input, then the receiving circuit is protected from damage, but the receiver noise figure increases and detection sensitivity deteriorates

Engineering Contradiction:
Improvereceiving circuit protectionVSAvoiddetection sensitivity
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The radar operation is temporarily stopped in advance when a moving body is detected approaching the antenna, preventing excessive reflected power from reaching the receiving circuit before it can cause damage. This preliminary protective action avoids the need for continuous power attenuation that would degrade detection sensitivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The radar device alternates between normal operation mode and temporary stop mode based on the presence of approaching moving bodies. During normal operation, full sensitivity is maintained; when a moving body is detected, the radar temporarily stops transmitting and receiving, creating a periodic on-off pattern that protects the circuit while preserving detection capability during active periods.

Inventive Principle:
Principle #19Periodic action

2Measurement precision

If radar operation continues without interruption to maintain detection capability, then detection sensitivity is preserved, but the receiving circuit may be damaged by excessive reflected power from approaching objects

Engineering Contradiction:
Improvedetection sensitivityVSAvoidreceiving circuit safety
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The determination unit continuously monitors radar detection results to detect approaching moving bodies, providing feedback to the controller. When a moving body is detected within the predetermined range, the controller receives this feedback and automatically stops the radar operation, creating a closed-loop protective system that balances detection sensitivity with circuit safety.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The controller acts as an intermediary between the determination unit and the radar operation control. It receives detection information from the determination unit and mediates the radar operation state, temporarily stopping transmission and reception when necessary to protect the receiving circuit while allowing normal operation when safe.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the radar operation is temporarily stopped to protect the receiving circuit, then the receiving circuit is protected from excessive power, but detection capability is reduced during the stop period

Engineering Contradiction:
Improvereceiving circuit protectionVSAvoiddetection capability
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The radar operation is temporarily stopped in advance when a moving body is detected approaching the antenna, preventing excessive reflected power from reaching the receiving circuit before it can cause damage. This preliminary protective action avoids the need for continuous power attenuation that would degrade detection sensitivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The radar device alternates between normal operation mode and temporary stop mode based on the presence of approaching moving bodies. During normal operation, full sensitivity is maintained; when a moving body is detected, the radar temporarily stops transmitting and receiving, creating a periodic on-off pattern that protects the circuit while preserving detection capability during active periods.

Inventive Principle:
Principle #19Periodic action

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 system effectively protects the receiving circuit from excessive power while maintaining detection sensitivity by automatically stopping radar operations as moving objects approach, enhancing power withstanding performance and reducing noise figure deterioration.

Implementation Method 1

a transmitting antenna 104... transmits the radar signal from a transmitting antenna 104

Methodology Applied
Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

the transmitted wave from the radar device 100 is reflected from the object T. The reflected wave from the object T is received by a receiving antenna 105

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

The reflected wave from the object T is received by a receiving antenna 105

Methodology Applied
Scientific EffectElectromagnetic radiation reception: Electromagnetic Induction

Implementation Method 4

mixed with the radar signal component transmitted from a power distributor 102 by means of a mixer 107 so as to be converted to an IF signal

Methodology Applied
Scientific EffectFrequency mixing: Heterodyne

Data Source

PatentEP3644089B1Radar device and radar system
Publication Date: 2022.10.19 HITACHI KOKUSAI ELECTRIC INC
  • EP3644089B1 patent drawingFigure 1
  • EP3644089B1 patent drawingFigure 2
  • EP3644089B1 patent drawingFigure 3

AI summary

Proposed is a technology that can protect a receiving circuit of a radar device from input of excessive reflected reception power. A radar device 200 is configured such that, upon detection of an object T within a detection range S, a movement determination unit 211 determines whether the object T is a moving object on the basis of the results of reception. If the object T is determined to be a moving object by the movement determination unit 211, a stoppage controller 212 stops the radar operation of the radar device 200 until the time calculated on the basis of the moving velocity of the object T has elapsed, from the point in time when the reception power reflected by the object T exceeds the preset threshold value Th.