RF Motion Sensor

Made a motion detecting sensor using radio frequency


Date: 2012
Category: Electronic Engineering Capstone Project Contest
Project Size: 1 Adviser(Professor) and 4 Electronic Engineers, 12 weeks
My Contribution: Electronic Engineering
Tools: PSpice


It was a project for an academic festival in 2012. We made a motion-detecting sensor using radiofrequency. It was a team project of 4 students in electronic engineering. We won the first prize in the 13th capstone design project at Sogang University.

the first prize at the 13th capstone design project in Sogang University


Infrared sensors and ultrasonic sensors are mainly used as motion sensors. Each sensor has its advantages and disadvantages. Infrared sensors have the potential for errors when detecting outdoor movements. Ultrasonic sensors have a short sensing distance and are impossible to precisely measure.


We thought it would be possible to engineer Radio Frequency motion sensors. Since RF motion sensor can offset the shortcomings of other types of motion sensors, we assumed that the RF motion sensor can be used alone or in combination with other sensors.

block diagram

circuit diagram


It can be used outdoors and it is harmless to the human body because it uses radiofrequency. Operating at low power makes it possible to create portable modules. It can also be easily combined with a communication system. Because radiofrequency can pass through obstacles, it can detect movement even if the sensor module itself is covered.


Based on the Doppler effect, a design was performed to detect motion using a transmit/receive antenna and a bandpass filter. We confirmed that we could detect motion through calculations, simulations, and actual tests. We installed a display light as an output to indicate motion detection.


The actual module was capable of measuring 360 degrees of motion in the 60 cm range and 270 degrees of motion in the 1-meter range. As a result, the RF motion sensor was completely developed to overcome the shortcomings of the existing sensors. If it is minimized, it can be used in various areas.

output hardware