Introducing the differences between the two detection methods of microwave sensors!

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BFS01/BSS01 / BSM02/BSS201-P1 /

last updated：Mar 12, 2026

PAL Inc.

Beam reflection method" and "beam interruption method

This time, we would like to introduce the differences in detection methods of our microwave sensors. We hope this will serve as a reference for customers who are unsure about which sensor to choose or want to know the type that suits their application. There are mainly two detection methods for microwave sensors: "beam reflection method" and "beam interruption method." The "beam reflection method" detects changes in the reflection of microwaves emitted from the sensor when they hit a person or object. It can be operated with a single sensor, making installation smooth and easy, even in limited spaces. Next, the "beam interruption method" involves placing the sensor and a reflector (or transmitter/receiver) opposite each other to detect the moment when the radio wave path is "interrupted." This method is ideal for situations where a clear monitoring line, such as a fence line, needs to be established, and it is widely used for perimeter security and gate monitoring. *For more details, please download the PDF or feel free to contact us.

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basic information

For more details, please refer to the PDF document or feel free to contact us.

Price range

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Delivery Time

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Applications/Examples of results

Perimeter surveillance/safety monitoring of important facilities

Detailed information

Detection of vehicles driving in the wrong direction
Prevention of contact with overhead cranes
Opening and closing of the vehicle gate
Monitoring of shrines and temples
Port facility intrusion detection
Prevention of contact with mobile cranes
Intrusion monitoring of power plants and substations
Detection of entry and exit at the railway vehicle depot.
Construction site security monitoring

Line up（5）

Model number	overview
BFS01	A safety monitoring sensor utilizing highly weather-resistant microwaves. Since it uses radio waves (microwaves), it is resilient to weather conditions such as rain, wind, snow, and fog, allowing for reliable measurements with fewer false detections even in harsh outdoor environments. It complies with the 24GHz band specific low-power radio station technical standards (ARIB STD-T73), eliminating the need for cumbersome radio station license applications for use. Additionally, it can be used indoors and outdoors throughout the country.
BSS01 / BSM02	An intrusion monitoring sensor that is highly resistant to natural environments and capable of distance measurement. Unlike conventional Doppler and infrared interruption methods, it detects intrusions based on distance and reflection levels by adopting the FMCW method. This has reduced false alarms compared to traditional methods. It complies with the technical standards certification (ARIB STD-T73) for 24GHz band specific low-power radio stations, eliminating the need for cumbersome radio station license applications during use. Additionally, it can be used both indoors and outdoors in the country.
BSS20	Terrorism prevention measures in critical infrastructure such as power plants and airports: 3D radio wave barriers reliably catch terrorists. Microwave smart sensors are intrusion monitoring sensors that use 24GHz band radio waves. They detect intruders by blocking the detection area composed of multiple opposing transmitters and receivers. *Compliant with the technical standards conformity certification for 24GHz band specified low power radio stations (ARIB STD-T73).
BSS201-P1／BSM201-P1	Security measures for factories and equipment: catering to various needs from simple installations to permanent setups. The microwave multi-span sensor BSS201-P1 is an intrusion detection sensor that uses 24GHz band radio waves. It detects intruders by blocking the detection area formed by a pair of transmitters and receivers. *Complies with the technical standards for specific low-power radio stations in the 24GHz band (ARIB STD-T73).
BSS300 / BSS301	Security and safety measures in factories and facilities can accommodate various needs from simple installations to permanent setups. Microwave short-range sensors can monitor nearby areas with a wide angle. They are resilient to changes in the surrounding environment, such as weather, and achieve low false alarm rates for intrusion monitoring.