Ai-Thinker Rd-03H 24GHz Human Presence Radar Module The Ai-Thinker Rd-03H is a compact 24GHz millimeter-wave radar module for human presence detection, motion detection, and slight-movement sensing. It uses ICLEGEND Micro's S1KM0000 radar SoC with a one-transmit, one-receive antenna design, making it suitable for embedded projects that need non-contact presence feedback in a slim DIP module format. Unlike simple PIR sensing, 24GHz FMCW radar can detect motion and micro-motion within the configured sensing area. The official Rd-03H specification lists up to 8m wall-mounted sensing distance, ±60° coverage, UART configuration, automatic detection-threshold generation, and a 35 × 7mm module size for compact device integration. For related OpenELAB radar options, compare the Ai-Thinker Rd-03 24G Millimeter Wave Radar V2, Ai-Thinker Rd-03D 24G Radar, Ai-Thinker Rd-03E 24G Radar, and Ai-Thinker Rd-03L V2 24G Human Presence Sensor. For evaluation and configuration workflows, the Ai-Thinker Radar Debugging Board is a useful companion accessory. Technical Specifications Parameter Value Brand Ai-Thinker Model Rd-03H OpenELAB SKU AT-Rd-03H Product Type 24GHz human presence detection radar module Radar SoC ICLEGEND Micro S1KM0000 Radar Technology FMCW millimeter-wave radar Frequency Range 24GHz to 24.25GHz ISM band Antenna Onboard 1T1R antenna Package DIP-5 with standard 2.54mm pin header spacing Module Size 35.0 × 7.0mm, ±0.2mm Maximum Sensing Distance Up to 8m for wall mounting in the ±60° range, based on Ai-Thinker open-space testing Ceiling Sensing Reference At 3m mounting height, circular projection radius is listed as 5m typical Detection Coverage Up to ±60° detection angle Supported Detection Moving human body and slight human movement detection Interface UART Default Baud Rate 115200 bps Pin Definition VCC, GND, TX, RX, IO Supply Voltage 3.0V to 3.6V, 3.3V typical; verify delivered hardware version before using 5V Recommended Supply Current At least 200mA available from the power supply Average Working Current 50mA typical at 3.3V and 25°C Operating Temperature -40°C to 85°C Storage Environment -40°C to 125°C, less than 90%RH Configuration Support Sensing range, interval sensitivity, unattended delay time, and automatic threshold generation Mounting Methods Wall mounting and ceiling mounting are supported by the official specification Integration Notes & Installation Guidance Power Supply — Use a stable 3.3V supply for the default version and reserve at least 200mA current capacity. Ripple Control — Ai-Thinker recommends LDO power where possible; if DC-DC is used, keep output ripple low and reserve suitable capacitors. UART Setup — Use the module UART interface for configuration and data communication, with 115200 bps as the listed default serial rate. Antenna Clearance — Keep metal parts and high-frequency devices away from the antenna area to avoid degrading radar performance. Stable Mounting — Fix the module firmly; vibration or shaking of the radar itself can affect detection results. Backside Interference — Avoid moving objects behind the radar, or use shielding when the installation environment creates unwanted backlobe detection. Multi-Radar Layout — When multiple 24GHz radar modules are used nearby, avoid direct beam alignment and increase spacing where possible. Environment Check — Large reflectors, moving curtains, pets, fans, plants, and air outlets can affect the detection result and should be considered during commissioning. ESD Handling — Treat the module as an electrostatic-sensitive device and use proper ESD handling during installation. Packing List 1 × Ai-Thinker Rd-03H 24GHz Human Presence Detection Radar Module FAQ Q: What is the main difference between Rd-03H and a PIR sensor?A: Rd-03H uses 24GHz millimeter-wave radar and can detect motion and slight human movement in the configured sensing area, while PIR sensors mainly respond to infrared changes. Q: What is the maximum detection distance?A: The official specification lists up to 8m in wall-mounted open-space testing within the ±60° range. Actual results depend on mounting position, environment, reflectors, and target condition. Q: What voltage should I use?A: Use 3.3V for the default version. The specification notes version-dependent voltage support, so verify the delivered hardware before applying 5V. Q: Which interface does the module use?A: The module supports UART communication, and the default serial rate is listed as 115200 bps. Q: Can it be ceiling mounted?A: Yes. The specification supports ceiling mounting and gives a 3m mounting-height reference with a 5m typical circular projection radius. Q: Why does the radar trigger when no person is present?A: Moving curtains, fans, pets, plants near air outlets, large reflectors, vibration, or moving objects behind the radar can cause false detection and should be checked during installation. Q: Does it need configuration?A: For best results, configure the sensing range, interval sensitivity, and delay settings according to the final installation environment.
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