RF for Emerging Applications Autonomous Vehicles and Robotics Informational

How do I design a compact radar sensor for a robotic collision avoidance system?

Q: Can this radar distinguish between a person and a wall?

Yes, with appropriate signal processing. A moving person has a non-zero Doppler signature (walking speed 1-2 m/s creates a 350-700 Hz Doppler shift at 77 GHz) while a wall has zero Doppler. Micro-Doppler analysis can further classify targets: a walking person has characteristic leg swing patterns, a rolling cart has a constant velocity signature. Machine learning classifiers trained on radar signatures can distinguish people, vehicles, shopping carts, and static structures with 85-95% accuracy.

Q: How much does a complete radar module cost?

In volume (10K+ units): radar SoC $10-25, PCB with antenna $3-8, passives and power management $2-5, assembly $2-5. Total BOM: $17-43. At production volumes of 100K+, costs drop to $12-30 per module. This is dramatically lower than lidar ($100-500) and competitive with multi-zone ultrasonic arrays ($15-40 for the equivalent detection coverage).

Q: What is the minimum detectable target size?

A 77 GHz radar with 4 GHz bandwidth and 12 dBi antenna can detect a human hand (RCS approximately 0.001-0.01 m^2) at 3-10 meters, a person (RCS approximately 0.5-2 m^2) at 15-50 meters, and a vehicle (RCS approximately 10-100 m^2) at 50-200 meters. The minimum detectable RCS depends on the radar's SNR at the given range, which is set by the transmit power, antenna gain, receiver noise figure, and processing gain.

Designing a compact radar sensor for robotic collision avoidance uses modern 60 GHz or 77 GHz radar-on-chip solutions that integrate the complete radar front end (transmitter, receiver, ADC, and digital signal processor) in a single IC package, enabling a complete radar sensor in a PCB footprint of 20x20 mm or smaller. The design process involves: selecting the radar SoC (Texas Instruments IWR6843/AWR1843 at 60/77 GHz, Infineon BGT60TR13C at 60 GHz, or NXP TEF82xx at 77 GHz; selection depends on required range, number of TX/RX channels, and processing capability), designing the antenna array (patch antenna arrays printed directly on the PCB; a 2x4 patch array provides 10-15 dBi gain with approximately 40-degree beamwidth in elevation and 80-degree in azimuth; the antenna design is tightly coupled to the PCB stack-up and must use low-loss substrate material like Rogers RO3003 or RO4835), implementing the FMCW signal processing chain (chirp configuration for the desired range and velocity resolution, 2D FFT for range-Doppler map generation, CFAR detection, and point cloud generation), and integrating collision avoidance logic (tracking detected objects, predicting collision trajectories, and generating avoidance commands to the robot controller). The resulting sensor can detect a person at 10-30 meters, a wall at 30-50 meters, and operate at an update rate of 10-30 Hz with total power consumption under 2 watts.

Category: RF for Emerging Applications

Updated: April 2026

Product Tie-In: Radar ICs, Antennas, FEMs

Compact Radar Design for Robotic Collision Avoidance

Radar-based collision avoidance is becoming standard in warehouse robots (AGVs), delivery robots, cleaning robots, and industrial cobots. Unlike ultrasonic sensors (limited range, narrow field of view) or lidar (expensive, limited in some environmental conditions), radar provides robust all-condition detection at low cost.

Radar SoC Selection Guide

TI IWR6843 (60 GHz): 3TX/4RX, integrated DSP and MCU, 4 GHz bandwidth, range resolution 3.75 cm. Designed for industrial sensing. $15-25 in volume
TI AWR1843 (77 GHz): 3TX/4RX, integrated DSP, 4 GHz bandwidth. Originally for automotive but widely used in robotics. $10-20 in volume
Infineon BGT60TR13C (60 GHz): 1TX/3RX, lower cost, simpler configuration. Suitable for short-range applications (<10 m). $5-10 in volume
NXP TEF82xx (77 GHz): 3TX/4RX, high-performance MIMO. Designed for automotive ADAS. $15-30 in volume

PCB Antenna Design

At 77 GHz (lambda = 3.9 mm), a half-wave patch element is approximately 1.3 x 1.3 mm (on Rogers RO3003, Er = 3.0). A 2x4 array of 8 elements fits in approximately 6 x 12 mm and provides approximately 12 dBi gain. The antenna feed network uses microstrip corporate feed with Wilkinson dividers. PCB substrate requirements: Er tolerance < 2%, loss tangent < 0.003 at 77 GHz, copper roughness < 0.5 um RMS. Standard FR4 is not suitable above approximately 10 GHz; Rogers or Isola high-frequency materials are required.

Compact Radar Design Parameters

77 GHz patch element: L = lambda / (2 x sqrt(Er_eff)) ~ 1.3 mm
Array gain: G = 10 log(N_elements) + G_element ~ 12 dBi for 2x4 array
Detection range: R = (P_tx G^2 lambda^2 sigma / ((4pi)^3 SNR_min))^(1/4)
For 10 dBm TX, 12 dBi, 1 m^2 RCS, 10 dB SNR: R ~ 50 m

Common Questions

Frequently Asked Questions

Can this radar distinguish between a person and a wall?

Yes, with appropriate signal processing. A moving person has a non-zero Doppler signature (walking speed 1-2 m/s creates a 350-700 Hz Doppler shift at 77 GHz) while a wall has zero Doppler. Micro-Doppler analysis can further classify targets: a walking person has characteristic leg swing patterns, a rolling cart has a constant velocity signature. Machine learning classifiers trained on radar signatures can distinguish people, vehicles, shopping carts, and static structures with 85-95% accuracy.

How much does a complete radar module cost?

In volume (10K+ units): radar SoC $10-25, PCB with antenna $3-8, passives and power management $2-5, assembly $2-5. Total BOM: $17-43. At production volumes of 100K+, costs drop to $12-30 per module. This is dramatically lower than lidar ($100-500) and competitive with multi-zone ultrasonic arrays ($15-40 for the equivalent detection coverage).

What is the minimum detectable target size?

A 77 GHz radar with 4 GHz bandwidth and 12 dBi antenna can detect a human hand (RCS approximately 0.001-0.01 m^2) at 3-10 meters, a person (RCS approximately 0.5-2 m^2) at 15-50 meters, and a vehicle (RCS approximately 10-100 m^2) at 50-200 meters. The minimum detectable RCS depends on the radar's SNR at the given range, which is set by the transmit power, antenna gain, receiver noise figure, and processing gain.

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