Microwave motion alarms and how they work
This type of alarm uses microwave energy to detect movement and trigger a signal, usually an audible alarm. The device emits microwaves within a given area, which then bounce off any obstacle that may be present and return to the source. The frequency of these returning waves is then measured and analyzed. If someone or something enters that area, it will cause a disturbance in the flow of microwaves and change the frequency. Once the sensor detects this, a signal will be transmitted to a remote device and the alarm will be set off.

Microwaves are advantageous in that they work better at covering a larger area. Microwave energy can also pass through obstacles, so this type of alarm can be comfortably placed behind walls, for example, and still work. The only drawback is that microwave motion alarms are quite sensitive and will react to electrical gadgets such as radios, wireless phones, etc.

Another issue about the sensitivity of microwave motion alarms is that they tend to react at the slightest disturbance, which can often lead to false alarms. Their sensitivity level can be adjusted, however, so they can fit the environment where they are installed.

Infrared motion alarms and how they work
This type of alarm was developed in the 80s and has since become the most popular technology used for security systems. An infrared-powered security device uses light energy that is in the frequency beyond the limit of visible light, which is red – hence the name ‘infrared’. The wavelength of infrared light is longer than lightwaves and shorter than radio waves, making it ideal for use in detecting heat.

In order for it to work as a type of alarm, an infrared device uses a sensor that detects and measures the temperature of an object that passes through the beam of light coming from the device. If it measures sufficient heat, such as that coming from a human body, the sensor will trigger an alarm.

Infrared motion alarms are cost-effective, making them a top choice as security devices. They cannot provide coverage for a full area but if installed in the right location, they can be very helpful for catching intruders in the act.