HB100 miniature microwave motion sensor breakout board

HB100 Microwave Motion Sensor – An Introduction


Electronics hobbyists, experimenters and constructors of microcontroller project frequently need to measure/detect voltage, current, frequency, temperature and… proximity. Most measure ments/detections can be carried out using pre-wired add-on modules integrated with suitable sensors/transducers. Unfortunately, real-motion detection requires rather more sophisticated and thus more expensive sensor. However, the microwave motion sensor module -HB100- introduced here makes the task sweet and simple. HB100 miniature microwave motion sensor is an X-band, Bi-static doppler transceiver module. This module is ideal for alarm, motion detection, vehicle speed measurement, automatic lighting, and door projects.

HB100 – General Features

  • Low current consumption (30mA typical)
  • CW or Pulse operation
  • Flat profile
  • Long detection range
  • Supply voltage: 4.75V and 5.25V
  • X band frequency: 10.525 GHz (typical)
  • Radiated power (EIRP): 12 dBm (minimum)

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The Doppler Effect

Doppler radar uses the same principles discovered by Christian Doppler when observing sound and applies them to electromagnetic waves. Using the Doppler Effect is a great way to measure relative speed. In practice, the Doppler Effect is a shift in frequency perceived by a receiver from a signal source due to relative movement of the sender and/or receiver. In a Doppler radar system, a known frequency signal is transmitted from an antenna which is pointed at a reference object. A separate antenna is used to receive the signal that is reflected back from the reference to measure the Doppler shift of the signal. A simple Doppler module, also called as the microwave motion sensor, can be easily integrated into multiple types of systems for various purposes. Doppler modules have an internal oscillator used to produce the signal frequency transmitted as the source. The received signal is then mixed with this set signal, which produces an output that is a sinusoid containing the frequency difference between the sender and receiver signals. Usually, these values need to be processed in a tangible way and is usually done with the help of a microcontroller.

HB100 outline diagram and antenna beam pattern

HB100 outline diagram and antenna beam pattern

HB100 – Insights

The HB100 module consists of Dielectric Resonator Oscillator (DRO), microwave mixer and patch antenna. The module operates at +5 Vdc for Continious wave (CW) operation, but module can be powered by +5V low duty cycle pulsed trains in order to reduce its power consumption (sample & hold circuit at the IF output is required for pulse operation). The following indicators should be considered when using the HB100 module.

  • There is no user adjustable part in this module to set the transmit frequency and power of the module
  • The module must be mounted with the antenna patches facing to the desired detection zone
  • The magnitude of the Doppler Shift (output from IF) is proportional to reflection of transmitted energy and is in the range of microvolts ( μV), and the frequency of Doppler shift is proportional to the velocity of motion (typical human walking generates Doppler shift below 100 Hz)
  • The received signal strength (RSS) is the voltage measured of the Doppler shift at the IF output
  • Special attention has to be given to the interference pick up from fluorescent light, as the 100/120 Hz noise is closed to the Doppler frequency generated by human movement. Similarly, rapid switching of certain devices (relay,motor, etc.) may generate high magnitude of transient noise at the IF terminal
  • DC level exists at the IF output and its polarity can be positive or negative. Its magnitude may vary over temperature. AC coupling is recommended for IF output connection
HB100 block diagram and connection pads

HB100 block diagram and connection pads

Quick Maths

The easiest way for a microcontroller to read data from an analog device is if it outputs a dc level voltage. Although some modules have this feature built into them, many others output just an AC signal, so a frequency-to voltage (F-V) circuit must be implemented. This F-V circuit can be used to calibrate the output data for a specific set of expected frequencies coming from the module to contain it in reference voltage range. Sampling of the available data and the manipulation of it through software is needed to make it useful for the system. This pre-processed value can then be manipulated using Doppler equations to find the speed of the target object.


Arduino + HB100 – Unlimited!

If you are in a plan to build something similar like an intelligent device on a door which alerts you about an attack in progress on the other side of the door, then go through this amazing Arduio + HB100 project:“Microwave Motion Sensors for Fun and Profit” (http://jpnelson. com/post/ 37623468093/microwave-motion-sensors-for-fun-and-profit-hb100). Author’s lab (TechNode PROTOLABZ) is waiting for the arrival of more HB100 modules from eBay, and you can expect another unsual Doppler Radar project from the author in near future!

One Comments

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  • Enrique San Martin

    I need HB100 miniature microwave motion sensor to momentarily trigger a relay, as a final task. Dear Gentlemen, I’ll appreciate and thank you to guide me (graphically if possible) how to proceed in order to get this goal, especially when target is moving at not less than 9 meters away from this sensor.

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