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Automotive Radar – Technology and Compliance

Q: How is radar-to-radar interference handled on crowded roads?

By waveform and processing design: chirp randomization/offsets, interference detection/blanking, adaptive notches, robust MIMO sequencing (TDM/FDM/CDM), and tracking filters to suppress ghost targets.

Q: What is a Radar Target Simulator (RTS), and is it required?

An RTS emulates controllable virtual targets (range, velocity, angle, RCS) for repeatable performance tests. It’s invaluable for development—but not strictly required for formal radio certification.

Q: What’s the difference between occupied bandwidth (OBW) and FMCW sweep bandwidth?

OBW is the regulatory emission bandwidth measured on a spectrum analyzer. FMCW sweep bandwidth defines range resolution (ΔR ≈ c/(2·B)).

Automotive radar operates in the millimeter-wave spectrum and enables reliable detection of distance, speed, and angle—independent of weather or lighting conditions. Most systems today use the harmonized 76–81 GHz bands, supporting long-, mid-, and short-range as well as 4D imaging radar. Additional bands such as 60 GHz for in-cabin sensing and 122 GHz+ for high-resolution applications are emerging.

Despite this technical convergence, international approval remains complex. Regional authorities define different limits for spectrum use, transmit power, and spurious emissions. Understanding these variations is essential for system design and global market access.

This guide provides an overview of the core technologies, key test parameters, and regulatory frameworks relevant to automotive radar in global markets.

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Explore our Automotive Radar Testing Services for EMC assessments, regional approvals, and global type certification.

Key Takeaways

Automotive radar mostly relies on FMCW modulation and MIMO arrays for robust detection across multiple bands – see Technology Overview.
Typical specifications such as frequency range, resolution, and beamwidth vary by use case (LRR, SRR, Interior, Research) – detailed in Technical Specifications.
Compliance assessment focuses on EIRP, occupied bandwidth, spurious emissions, antenna patterns, conducted output power and interference robustness – outlined under Test Parameters and Measurement Techniques.
While the 76–77 GHz band is harmonized globally, in the 77-81 GHz band Japan as well as the EU apply lower EIRP limits and China still restricts to 76–79 GHz – check Regulatory Requirements.
Real-world use cases include highway ACC, blind-spot detection, cabin monitoring, and smart city traffic sensing – highlighted in Real-World Examples.

Technology Overview

Automotive radar systems operate in the millimeter-wave spectrum, providing reliable object detection under all weather and lighting conditions.

Key Capabilities

Weather-independent operation – reliable in rain, fog, snow, and darkness.
Multi-band coverage – 24–81 GHz in current use, with 122+ GHz in certain fields already on the market, also under development for next-generation high-resolution radar.
High-precision detection – range resolution down to 5 cm with today’s technology.
360-degree vehicle coverage – achieved through multiple sensors and sensor fusion.
Real-time velocity measurement – based on the Doppler effect, the frequency shift caused by motion.

Industry trend

The sector is shifting from legacy 24 GHz solutions to the harmonized 76–81 GHz band for exterior radar (LRR, SRR, 4D imaging). Interior radar typically uses 60 GHz for cabin monitoring and gesture control.

System design

Alongside these frequency allocations, the underlying radar architecture defines how detection performance is achieved. Automotive radar predominantly employs FMCW modulation (Frequency-Modulated Continuous Wave) and MIMO arrays (Multiple Input Multiple Output). Together with cameras and lidar, they form a core sensing pillar for advanced driver assistance. Research into 122 GHz+ aims to enable sub-3 cm resolution for future generations.

The next section examines modulation principles and antenna design, which are critical factors for radar system performance.

Modulation and Antenna Design

Signal Forms

FMCW (Frequency-Modulated Continuous Wave): The current standard in automotive radar. Linear frequency sweeps ("chirps") allow simultaneous distance and velocity measurement with high accuracy at comparatively low transmit power—ideal for continuous operation.
Pulse Radar: Historically used, for example in legacy 24 GHz concepts. Requires very high peak power and has largely been replaced by FMCW in modern designs.

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FMCW Signal Pattern

FMCW uses continuous-wave transmission. The frequency sweeps linearly within each chirp — typically a sawtooth up-ramp with fast reset; triangular up/down is also common.

Continuous: Always transmitting (no gaps)
Frequency Modulated: Transmission frequency changes over time
Chirps: Each frequency sweep measures distance

Pulse Signal Pattern

Pulse radar sends short bursts then listens. Distance is measured by timing the delay between transmit and echo.

Pulsed Operation: Transmit → Listen → Echo → Measure
High Peak Power: Short bursts with very high instantaneous power
Low Duty Cycle: Transmits only a fraction of the time (<< 1%)
Time-of-Flight: Distance measurement from transmit-to-echo delay

Antenna Characteristics

Beamwidth vs. range/gain: Narrow beams with higher antenna gain focus energy for longer detection ranges. Wider beams reduce maximum range but provide broader coverage.
MIMO arrays and beamforming: Multiple transmit/receive elements enable digital beam steering and significantly improve angular resolution across radar classes.
Bandwidth vs. range resolution: Range resolution improves with larger RF sweep bandwidth, expressed as ΔR ≈ c / (2·B), where ΔR = resolution, c = speed of light, and B = bandwidth. Short-range and imaging radars usually use wider sweeps than long-range sensors.

The beam pattern examples below demonstrate these antenna principles.

Radar Beam Pattern

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Interactive beam pattern visualization —
Different radar configurations

Narrow Beam Pattern

Narrow beams concentrate radar energy for maximum range and precision.

High Gain: Focused energy extends detection range
Precise Targeting: Sharp beam for accurate localization
Application: Long-range radar for highway ACC

Wide Beam Pattern

Wide beams provide comprehensive coverage at shorter ranges.

Broad Coverage: Wide field of view for lateral detection
Urban Scenarios: Ideal for close-range detection
Application: Short-range radar for parking assistance

MIMO Array Pattern

Multiple-Input Multiple-Output arrays enable advanced beam control.

Adaptive Steering: Digital beamforming in real-time
Multiple Targets: Simultaneous object tracking
Application: Next-generation radar systems

Beyond beam characteristics, automotive radar development is closely tied to frequency allocation. The next section outlines the main radar bands and their regulatory status worldwide.

Radar Frequency Bands

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Click on a frequency band for regulatory details

76–81 GHz Main Band (3 Sub-ranges)

LRR Sub-band: 76–77 GHz (1 GHz) – narrow beam, up to 250 m range, ~15 cm resolution
SRR Sub-band: 77–81 GHz (4 GHz) – wide coverage, up to 100 m range, ~7.5 cm resolution
Imaging (combined): 76–81 GHz (up to 5 GHz) – current standard for high-resolution imaging (4D radar), up to 200 m, ~5 cm resolution
Wavelength: ~3.9 mm (all sub-bands)
Applications: LRR for ACC/AEB, SRR for blind spot/parking, Imaging for object classification
Regulatory: The 76–81 GHz band is broadly harmonized and approved for automotive radar in the EU, USA, Canada, Brazil, Korea, and Japan (with lower power limits). In China, only 76–79 GHz is currently authorized, with expansion under review

24 GHz Radar (Legacy)

Frequency Band: 24.05-24.25 GHz
Bandwidth: ~200 MHz
Wavelength: ~12.5 mm
Range: up to 30 m
Resolution: ~75 cm
Beam Width: 60–150°
Applications: Blind spot detection, parking assistance

Regulatory Status: In the EU, 24 GHz SRR phased out as of January 1, 2022. In the U.S., 24.05–24.25 GHz remains permitted under FCC Part 15.249 for general SRD. Automotive SRR in this band is considered legacy/sunset and is no longer certified for new designs.

60 GHz Interior Radar

Frequency Band: 57-64 GHz
Bandwidth: up to 7 GHz
Wavelength: ~5 mm
Range: up to 5 m
Resolution: ~2 cm
Beam Width: ~120°
Applications: Occupancy detection, gesture control, vital sign monitoring

Technical Advantages: High resolution, compact antennas. 60 GHz sensors are increasingly replacing 24 GHz interior solutions. The signals remain largely confined within the vehicle cabin, minimizing external interference.

76–81 GHz Main Band (3 Sub-ranges)

LRR Sub-band: 76–77 GHz (1 GHz) – narrow beam, up to 250 m range, ~15 cm resolution
SRR Sub-band: 77–81 GHz (4 GHz) – wide coverage, up to 100 m range, ~7.5 cm resolution
Imaging (combined): 76–81 GHz (up to 5 GHz) – current standard for high-resolution imaging (4D radar), up to 200 m, ~5 cm resolution
Wavelength: ~3.9 mm (all sub-bands)
Applications: LRR for ACC/AEB, SRR for blind spot/parking, Imaging for object classification

Regulatory Status: The 76–81 GHz band is broadly harmonized and approved for automotive radar in the EU, USA, Canada, Brazil, Korea, and Japan (with lower power limits). In China, only 76–79 GHz is currently authorized, with expansion under review.

122+ GHz Research

Frequency Bands: 122.25-130 GHz, 134-148.5 GHz
Regulation: ECC Decision (22)03
Bandwidth: >20 GHz available
Wavelength: ~2-2.5 mm
Range: Long-range potential (implementation dependent)
Resolution: <3 cm
Beam Width: 5–120° (application dependent)

Regulatory Status: Emerging Technology – ECC Decision (22)03 harmonizes 116-260 GHz. First prototypes available, series production expected from ~2027. Enables next-generation ultra-HD radar imaging.

Building on these frequency allocations, the next section illustrates how radar sensors are positioned around the vehicle and how different radar classes contribute to full coverage.

Radar Sensor Positions

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Click on an area or button for details

Front Radar Systems

Modern vehicles typically use one to three front-mounted radar sensors with complementary roles:

Long-Range Radar (LRR): Narrow field of view for highway ACC/AEB and gap control.
Short-Range Radar (SRR): Wider field of view for urban scenarios and cut-ins.
4D Imaging Radar: High-resolution perception to enhance object classification and lane-level decisions.

Integration: Grille or behind bumper; often combined with camera/lidar in sensor fusion.

Corner Radar Systems

Role: Wide coverage for blind-spot monitoring, lane change assist, cross-traffic alert, and parking maneuvers.
Placement: Rear corners and/or front corners for 360° coverage.

Note: Optimized for lateral awareness and close-range separation of adjacent objects.

Side Radar Systems

Role: Lateral collision avoidance, door-opening warnings, cyclist detection in urban traffic.
Placement: Vehicle sides (e.g., mirrors, doors, rocker area).

Note: Very wide field of view prioritizes side coverage over maximum range.

Rear Radar Systems

Role: Rear collision warning, reverse assistance, rear cross-traffic alert, trailer monitoring.
Placement: Center and/or corners of the rear bumper.

Note: Calibrated for approaching objects from behind and oblique angles.

Interior Radar Systems

Role: Occupancy detection, child-presence detection, vital-sign monitoring, gesture control.
Placement: Roof module or dashboard integration.

Note: Signals remain largely confined to the cabin, reducing external interference.

Each radar position relates to a specific class with defined frequency ranges, resolution, and beam characteristics. These are summarized in the specification table below.

Technical Specifications

Comparison of key specifications for automotive radar classes (24 GHz legacy, 60 GHz interior, 76–81 GHz LRR/SRR, 122+ GHz research).

Radar Type	Technical Details
24 GHz (Legacy)	Frequency Band: 24.05–24.25 GHz Bandwidth: ~200 MHz Wavelength: ~12.5 mm Range: up to 30 m Resolution: ~75 cm Beam Width: 60–150° Application: Blind spot, Parking
60 GHz (Interior Only) [1]	Frequency Band: 57–64 GHz Bandwidth: up to 7 GHz Wavelength: ~5 mm Range: up to 5 m Resolution: ~2 cm Beam Width: ~120° Application: Interior Gesture, Cabin Occupancy
76–77 GHz (LRR)	Frequency Band: 76–77 GHz Bandwidth: 1 GHz Wavelength: ~3.9 mm Range: up to 250 m Resolution: ~15 cm Beam Width: 10–20° Application: ACC, AEB
77–81 GHz (SRR) [3][4]	Frequency Band: 77–81 GHz Bandwidth: 4 GHz Wavelength: ~3.9 mm Range: up to 100 m [3] Resolution: ~7.5 cm Beam Width: 60–150° [4] Application: Corner, Park, BSD
76–81 GHz (Imaging)	Frequency Band: 76–81 GHz Bandwidth: up to 5 GHz Wavelength: ~3.9 mm Range: up to 200 m Resolution: ~5 cm Beam Width: 60–120° [4] Application: HD Object Detection
122+ GHz (Research) [2]	Frequency Band: 122.25–130 / 134–148.5 GHz Bandwidth: >20 GHz (total) Wavelength: ~2–2.5 mm Range: Long-range potential Resolution: <3 cm Beam Width: 5–120° Application: Ultra-HD Imaging (Future)

Parameter	24 GHz (Legacy)	60 GHz (Interior Only) [1]	76–77 GHz (LRR)	77–81 GHz (SRR) [3][4]	76–81 GHz (Imaging)	122+ GHz (Research) [2]
Frequency Band	24.05–24.25 GHz	57–64 GHz	76–77 GHz	77–81 GHz	76–81 GHz	122.25–130 / 134–148.5 GHz
Bandwidth	~200 MHz	up to 7 GHz	1 GHz	4 GHz	up to 5 GHz	>20 GHz (total)
Wavelength	~12.5 mm	~5 mm	~3.9 mm	~3.9 mm	~3.9 mm	~2–2.5 mm
Range	up to 30 m	up to 5 m	up to 250 m	up to 100 m [3]	up to 200 m	Long-range potential
Resolution	~75 cm	~2 cm	~15 cm	~7.5 cm	~5 cm	<3 cm
Beam Width	60–150°	~120°	10–20°	60–150° [4]	60–120° [4]	5–120°
Application	Blind spot, Parking	Interior Gesture, Cabin Occupancy	ACC, AEB	Corner, Park, BSD	HD Object Detection	Ultra-HD Imaging (Future)

Footnotes:

60 GHz is exclusively for interior/cabin applications (not for external automotive radar).
122+ GHz bands are currently in research phase, not yet commercially deployed in automotive.
SRR range varies by: Side ~20 m, Rear ~60 m, Corner ~100 m.
Side radars may use up to 180° field of view for lateral coverage.

Note: Values represent typical specifications for each radar class. Actual performance varies based on:

Antenna gain and design configuration
Signal processing techniques (FMCW, MIMO, chirp configuration)
Vehicle integration and regulatory limits (EIRP)
Environmental conditions and target characteristics

While the table above summarizes typical specifications, the next section highlights the key test parameters and measurement techniques used to verify compliance and performance.

Test Parameters and Measurement Techniques

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RF & Power Testing

Core radio frequency and power measurements for regulatory compliance:

Operating Frequency & Bandwidth: Verification of center frequency and occupied bandwidth (OBW) per region; note this differs per region due to different regulatory test parameters.¹
Transmit Power (EIRP): Measurement of average and peak power, including duty cycle considerations.
Spurious & Out-of-Band Emissions: Ensuring unwanted emissions remain below regulatory limits.
Modulation Accuracy: Verification of FMCW chirp linearity, sweep deviation, and timing accuracy.
Frequency Stability: Under temperature and voltage variation.

Antenna & Beam Testing

Antenna performance and beam pattern characterization:

Antenna Characteristics: Beamwidth, antenna gain, and sidelobe levels impacting range and interference potential.
MIMO/Beamforming Validation: Multi-antenna test setups to evaluate digital beam steering and angular separation.
Frame/Chirp Timing & MIMO Sequencing: Frame rate, chirp duration, and TX sequencing (TDM/FDM/CDM) to maintain channel orthogonality.
Integration & Radome Testing: Evaluation of sensor performance under real installation and bumper/radome conditions.

Performance Testing

System-level performance and accuracy validation:

Resolution Metrics: Range, Doppler (velocity), and angular resolution evaluated against system specifications.
Accuracy & Sensitivity: Range/velocity/angle accuracy and minimum detectable RCS/SNR thresholds.²
Receiver Dynamic Range & Linearity: Strong-target/clutter handling without desensitization; multipath robustness.
Interference Robustness: Performance in multi-radar environments (FMCW-to-FMCW), mitigation against ghost targets and self-interference.
Radar Target Simulators (RTS): Emulate range/Doppler/angle targets for repeatable tests without large physical ranges.
Environmental Test Support: Climatic and vibration testing to assess performance under automotive conditions.
Calibration & Uncertainty: ISO/IEC 17025 traceability and uncertainty budgets for measurement confidence.

Lab Equipment

Specialized equipment and test environments for automotive radar validation:

Anechoic Chambers (OTA): Power, emission, and beam pattern measurements.
Vector Signal Generators & Analyzers: Chirp analysis, bandwidth, and modulation verification.
Turntables & Positioners: Precise angular positioning for beam characterization.
MIMO/Beamforming Rigs: Multi-channel TX/RX setups for steering and channel orthogonality.
CATR or Near-Field-to-Far-Field (NF-FF): Compact ranges or NF→FF transformation for accurate patterns/gain.³

Footnotes:

OBW vs. Sweep Bandwidth: OBW (occupied bandwidth) refers to the regulated emission bandwidth, mesured by given regulatory prcedures. FMCW sweep bandwidth determines range resolution.
Sensitivity / RCS: Sensitivity is often defined as the minimum detectable Radar Cross Section (RCS) at a given SNR, depending on target size and reflectivity.
CATR / NF–FF: Compact Antenna Test Range (CATR) and Near-Field-to-Far-Field (NF–FF) methods provide equivalent far-field antenna results in a compact test setup.

Beyond the measurement parameters themselves, the test environment and geometric setup are equally critical to ensure accurate and repeatable results.

Measurement Setup

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OTA & Geometry

Test environment configuration and geometrical considerations:

Test environments: Fully shielded halls / anechoic chambers for type approval; smaller anechoic rooms are fine for R&D.
Far-field criterion & distance correction: Use R_FF ≈ 2D²/λ; common 3 m / 10 m geometries are corrected to 1 m for absolute EIRP ^1,2.
CATR / NF-to-FF: Compact far-field via CATR or probe scanning with NF→FF transformation; define method per DUT aperture and range.
Quiet zone (QZ): Specify QZ size and field uniformity so the DUT sits entirely in valid far-field.
Safety & shielding: RF containment, interlocks, exposure checks.

Equipment & Calibration

Instrumentation and calibration procedures:

Spectrum analyzer + horn: Power/emission & spurious scans; apply antenna factor and path-loss corrections for absolute EIRP ².
VSG/VSA: Chirp/sweep verification and modulation accuracy (slope, deviation).
Low-noise preamps: Extend sensitivity to meet very low spurious limits.
Multi-channel timing: Phase-coherent TX/RX, trigger I/O, frame/chirp timing (TDM/FDM/CDM) to maintain orthogonality.
Beat-frequency linearity: Feed TX (via attenuator) into a mixer with a reference LO; analyze the baseband beat note for slope linearity/deviations.
Direct IF sampling: High-speed ADC on RX/IF; evaluate slope non-linearity and timing jitter via DSP.
System calibration: Reference antenna + power meter for absolute EIRP/gain; traceable uncertainty budget.

Targets & Simulation

Target setup and simulation methods:

Fixed reflectors: Calibrated spheres/plates at known ranges (e.g., 10 m / 20 m / 30 m) to verify range bins and reported distances.
Radar target simulator (RTS): Horn-coupled digital simulator with full control of virtual targets (range, radial velocity, RCS) for repeatable scenarios.
Turntables & elevation masts: Azimuth/elevation sweeps (e.g., 1° steps) for full pattern capture.
Alignment & referencing: Laser/optical alignment; shared 10 MHz reference and PPS sync across instruments.

Integration & Validation

Real-world integration and validation procedures:

Radome/vehicle fixtures: Quantify bumper/radome detuning and insertion loss; use realistic mounts and harness routing.
Environmental conditioning: Repeat key measurements at min/max supply and temperature extremes (climatic chamber with RF feed-through).
Patterns, sidelobes & sensitivity: 360° capture, sidelobe levels, detection thresholds.
R&D vs. type-approval: Flexible R&D setups vs. normative methods in certified chambers; full logs, traceability, and repeated runs (typically 2–3) to substantiate conformity.
Dynamic testing: Proving-ground trials with rail-guided dummies or remote platforms to validate behavior for OEM release.

Footnotes:

Far-field formula: R_FF ≈ 2D²/λ (D = largest antenna dimension).
EIRP conversion: 3 m / 10 m chamber measurements are distance-corrected to 1 m; include antenna factor and path-loss corrections.

While these setups define how measurements are carried out, regulatory frameworks determine which parameters must be validated in each market.

Regulatory Requirements

Requirements by Region

The table below summarizes key automotive radar approval requirements across major jurisdictions.

Region / Authority	Details
EU – CE / RED	Authorized Band: 76–81 GHz (EN 301 091 / EN 302 264) Certification Path: CE marking (self-declaration under RED) Remarks: Max. 55 dBm peak EIRP; 60 GHz partly under EN 305 550
USA – FCC	Authorized Band: 76–81 GHz (Part 95 Subpart M) Certification Path: FCC certification via TCB Remarks: 50 dBm average / 55 dBm peak; 57–71 GHz interior via §15.255
Canada – ISED	Authorized Band: 76–81 GHz (RSS-251) Certification Path: ISED certification (IC No.) Remarks: 50 dBm average / 55 dBm peak; 60 GHz via RSS-210
Japan – MIC	Authorized Band: 76–81 GHz (ARIB STD-T48/T111) Certification Path: MIC type approval (via TELEC) Remarks: Labeling required
China – MIIT	Authorized Band: 76–79 GHz only¹ Certification Path: SRRC type approval (MIIT ID) Remarks: Expansion to 81 GHz under review¹
Korea – KCC	Authorized Band: 76–81 GHz Certification Path: KC certification Remarks: Aligned with CEPT; KC certification mandatory; EU test report recognition common in practice
Brazil – ANATEL	Authorized Band: 76–81 GHz (Res. 755/2020, Res. 700) Certification Path: ANATEL homologation Remarks: Limits harmonized with FCC/ETSI (~55 dBm); local ANATEL ID mandatory

Region / Authority	Authorized Band	Certification Path	Remarks
EU – CE / RED	76–81 GHz (EN 301 091 / EN 302 264)	CE marking (self-declaration under RED)	Max. 55 dBm peak EIRP; 60 GHz partly under EN 305 550
USA – FCC	76–81 GHz (Part 95 Subpart M)	FCC certification via TCB	50 dBm average / 55 dBm peak; 57–71 GHz interior via §15.255
Canada – ISED	76–81 GHz (RSS-251)	ISED certification (IC No.)	50 dBm average / 55 dBm peak; 60 GHz via RSS-210
Japan – MIC	76–81 GHz (ARIB STD-T48/T111)	MIC type approval (via TELEC)	Labeling required
China – MIIT	76–79 GHz only¹	SRRC type approval (MIIT ID)	Expansion to 81 GHz under review¹
Korea – KCC	76–81 GHz	KC certification	Aligned with CEPT; KC certification mandatory; EU test report recognition common in practice
Brazil – ANATEL	76–81 GHz (Res. 755/2020, Res. 700)	ANATEL homologation	Limits harmonized with FCC/ETSI (~55 dBm); local ANATEL ID mandatory

Footnotes:

China restriction: China currently authorizes only 76–79 GHz for automotive radar; extension to 81 GHz is under regulatory review.

Requirements by Frequency Band

The table below summarizes frequency allocations and typical power limits across major markets.

Frequency Band	Details
24.05–24.25 GHz	EU (CEPT): Legacy only USA (FCC): Legacy (Part 15.249), ~10 mW Canada (ISED): Legacy (RSS-210 Annex B) Japan (MIC/ARIB): Legacy (ARIB STD-T308), ~20 mW China (MIIT): Phased out since 2022
76–77 GHz	EU (CEPT): EN 301 091; 55 dBm peak USA (FCC): Part 95M; 50 avg / 55 peak Canada (ISED): RSS-251; 50 avg / 55 peak Japan (MIC/ARIB): ARIB STD-T48; ~45 dBm China (MIIT): Authorized (within 76–79 GHz)¹
77–81 GHz	EU (CEPT): EN 302 264; 55 dBm peak USA (FCC): Part 95M; same as above Canada (ISED): RSS-251; same as above Japan (MIC/ARIB): ARIB STD-T111; ~45 dBm China (MIIT): 79–81 GHz under review¹
57–64 GHz (Interior)	EU (CEPT): EN 305 550; ~20 dBm USA (FCC): Part 15.255 (57–71 GHz); +10 dBm Canada (ISED): RSS-210 Annex J (57–71 GHz); +10 dBm Japan (MIC/ARIB): Limited use (ARIB drafts) China (MIIT): Under evaluation
122–130 GHz / >134 GHz	EU (CEPT): EN 305 550 (UWB sensors, ~20 dBm) USA (FCC): Part 15.258 (116–123 GHz); up to 53 dBm Canada (ISED): Drafts in progress Japan (MIC/ARIB): Regulations in preparation China (MIIT): Pilot projects, draft rules

Frequency Band	EU (CEPT)	USA (FCC)	Canada (ISED)	Japan (MIC/ARIB)	China (MIIT)
24.05–24.25 GHz	Legacy only	Legacy (Part 15.249), ~10 mW	Legacy (RSS-210 Annex B)	Legacy (ARIB STD-T308), ~20 mW	Phased out since 2022
76–77 GHz	EN 301 091; 55 dBm peak	Part 95M; 50 avg / 55 peak	RSS-251; 50 avg / 55 peak	ARIB STD-T48; ~45 dBm	Authorized (within 76–79 GHz)¹
77–81 GHz	EN 302 264; 55 dBm peak	Part 95M; same as above	RSS-251; same as above	ARIB STD-T111; ~45 dBm	79–81 GHz under review¹
57–64 GHz (Interior)	EN 305 550; ~20 dBm	Part 15.255 (57–71 GHz); +10 dBm	RSS-210 Annex J (57–71 GHz); +10 dBm	Limited use (ARIB drafts)	Under evaluation
122–130 GHz / >134 GHz	EN 305 550 (UWB sensors, ~20 dBm)	Part 15.258 (116–123 GHz); up to 53 dBm	Drafts in progress	Regulations in preparation	Pilot projects, draft rules

Footnotes:

China restriction: China currently authorizes only 76–79 GHz for automotive radar; extension to 81 GHz is under regulatory review.

Supplementary EMC Requirements – ECE R10

In addition to radio regulations (e.g., RED, FCC, ISED, MIC), radar systems installed in vehicles must comply with UNECE Regulation No. 10 (ECE R10).
It defines the EMC requirements for electrical and electronic vehicle components and is a prerequisite for type approval in the automotive sector.
→ Further details: ECE R10

Real-World Examples

These examples demonstrate how automotive radar is deployed in real-world systems—highlighting technical challenges and solutions for integration, testing, and regulatory approval.

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Long-Range Front Radar for ACC/AEB

Application context

A premium vehicle platform integrated a 76–77 GHz long-range radar (LRR) into the front grille to enable adaptive cruise control (ACC) and automatic emergency braking (AEB). The system monitored traffic up to ~200 m ahead, ensuring safe distance keeping and collision avoidance at highway speeds.

Technical implementation

The module operated in the 76–77 GHz band with ~0.8–1 GHz sweep bandwidth (≈ 15–20 cm range resolution). Typical transmit power was ~45 dBm EIRP, kept below the 55 dBm peak limit. A 10–20° narrow beam maximized detection range and accuracy. FMCW chirps with MIMO antenna arrays supported robust object tracking and classification in dense traffic.

Testing and compliance

Validation included far-field chamber tests for EIRP and spurious emissions, plus CATR measurements for antenna patterns. Chirp linearity and timing are verified with real-time signal analyzers; radar target simulators emulated vehicles at varying ranges and speeds. Regulatory approval followed EN 301 091 (EU), FCC Part 95 Subpart M (USA), and RSS-251 (Canada). For Japan, firmware limited EIRP (~45 dBm) per ARIB STD-T48.

Result and impact

The radar reliably detected vehicles up to 200 m, enabling smooth cruise control and early emergency braking. Firmware-based regional adaptations ensured worldwide compliance without hardware redesign.

Blind Spot Detection with Corner Radars

Application context

An OEM integrated 77–81 GHz short-range radars (SRR) behind the rear bumper corners to enable blind spot detection, lane-change assist, and rear cross-traffic alert. Coverage extended to adjacent lanes up to ~50–60 m, with stable performance in rain, fog, and low light.

Technical implementation

Each module used <4 GHz sweep bandwidth (~7.5 cm range resolution). Wide beamwidth (120–150°) covered adjacent lanes; MIMO processing improved angular separation of closely spaced targets.

Testing and compliance

CATR pattern measurements and anechoic spurious scans established compliance. Range accuracy was verified using radar target simulators; bumper integration was assessed for radome loss and detuning. Approvals were obtained under ETSI EN 302 264 (EU), FCC Part 95 (USA), and RSS-251 (Canada).

Result and impact

The system reliably detected vehicles up to two lanes away, improving safety during lane changes and highway merges. Regional EIRP profiles enabled global rollout without hardware changes.

Interior Radar for Cabin Monitoring

Application context

A tier-one supplier implemented 60 GHz interior radar modules to detect cabin occupancy, child presence, and enable gesture control. Sensors in the roof module and dashboard covered the entire cabin without cameras.

Technical implementation

Operating in 57–64 GHz with up to 7 GHz sweep bandwidth, the system achieved ~2 cm range resolution. Transmit power was limited to ~20 dBm EIRP in Europe and ~10 dBm in the USA. Ultra-wideband FMCW operation captured micro-motions (e.g., breathing); antennas with ~120° beamwidth provided full cabin coverage.

Testing and compliance

Power and emissions were evaluated per EN 305 550 (EU), FCC §15.255 (USA), and RSS-210 Annex J (Canada). Verification included range accuracy under climatic stress and material effects through windshield/headliner. For Japan, emission limits are usually adjusted via firmware, since emission limity vary by use case. Exposure assessments confirmed compliance with relevant limits.

Result and impact

The radar reliably detected occupants and vital signs, preventing child-presence incidents and enabling intuitive HMI via gestures. Firmware profiles ensured market-specific compliance without hardware variants.

Smart City Traffic Monitoring with 77 GHz Radar

Application context

A municipality deployed 77 GHz radar at intersections to monitor traffic flow, detect stopped vehicles, and improve pedestrian safety. The sensors provided continuous coverage regardless of weather or lighting conditions.

Technical implementation

Operating in 76–77 GHz with ~1 GHz sweep bandwidth (~15 cm range resolution) and up to ~55 dBm peak EIRP, the system covered lane segments up to ~100 m with a field-of-view of ~30 m width. Electronically steered beams observed multiple traffic zones simultaneously.

Testing and compliance

Type approval used EN 301 091-2 (EU) for transport and traffic telematics (TTT) radars; pattern and emission tests employed CATR and anechoic setups. For North America, testing followed FCC Part 95 and RSS-251.

Result and impact

The system reliably detected vehicles and pedestrians across complex intersections, reducing accidents and optimizing signal timing. Harmonized allocations enabled one hardware platform with minor firmware adaptations across markets.

FAQ – Practical Questions

Do I need separate approvals for each country?

Yes. Even with widely harmonized 76–81 GHz rules, each market requires its own approval (EU CE/RED, US FCC via TCB, Canada ISED, Japan MIC/TELEC, Korea KC, Brazil ANATEL, China SRRC).

Can I reuse test reports across regions?

Partially. High-quality RF/OTA reports (EIRP, OBW, spurious, patterns) can support multiple filings, but each authority still needs its own application and any country-specific checks (e.g., labeling).

Do I need ISO/IEC 17025 traceability and an uncertainty budget?

Yes. Authorities expect accredited calibration chains and stated measurement uncertainty for type-approval evidence.

Which documentation should I prepare for approval?

Block diagram; antenna/radome specs; chirp parameters; RF/OTA reports (EIRP, OBW vs. sweep bandwidth, spurious, patterns); exposure assessment (if applicable); installation/user info; label drafts/photos; declarations/certificates.

How is radar-to-radar interference handled on crowded roads?

By waveform and processing design: chirp randomization/offsets, interference detection/blanking, adaptive notches, robust MIMO sequencing (TDM/FDM/CDM), and tracking filters to suppress ghost targets.

What is a Radar Target Simulator (RTS), and is it required?

An RTS emulates controllable virtual targets (range, velocity, angle, RCS) for repeatable performance tests. It’s invaluable for development—but not strictly required for formal radio certification.

What’s the difference between occupied bandwidth (OBW) and FMCW sweep bandwidth?

OBW is the regulatory emission bandwidth measured on a spectrum analyzer. FMCW sweep bandwidth defines range resolution (ΔR ≈ c/(2·B)).

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Automotive Radar – Technology and Compliance

Key Takeaways

Technology Overview

Key Capabilities

Industry trend

System design

Modulation and Antenna Design

Signal Forms

Antenna Characteristics

Radar Beam Pattern

Radar Frequency Bands

76–81 GHz Main Band (3 Sub-ranges)

Radar Sensor Positions

Technical Specifications

Test Parameters and Measurement Techniques

Measurement Setup

Regulatory Requirements

Requirements by Region

Footnotes:

Requirements by Frequency Band

Footnotes:

Supplementary EMC Requirements – ECE R10

Real-World Examples

FAQ – Practical Questions

Do I need separate approvals for each country?

Can I reuse test reports across regions?

Do I need ISO/IEC 17025 traceability and an uncertainty budget?

Which documentation should I prepare for approval?

How is radar-to-radar interference handled on crowded roads?

What is a Radar Target Simulator (RTS), and is it required?

What’s the difference between occupied bandwidth (OBW) and FMCW sweep bandwidth?

Looking for Support?

Further Reading & Official Resources

Selected Automotive Radar Regulations by Key Market

Additional Resource

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