Infrared Radars and Microwave Radars for Automatic Sliding Doors

The core differences between infrared radars and microwave radars used in automatic sliding doors lie in their induction principles, applicable scenarios, anti-interference capabilities, etc. The specific comparisons and characteristics are as follows.

I. Differences in Induction Principles

▪  Infrared Radar operates based on infrared reflection detection and is divided into active and passive types. Active infrared sensing is commonly used for automatic doors.

The sensor emits infrared rays of a specific wavelength. When a human body or object enters the sensing range, it reflects the infrared signal.

The receiver detects changes in the reflected signal (such as signal intensity and reflection angle), determines the presence of a moving object, and then triggers the door to open.

Essentially, it detects "the reflection of infrared rays by objects" and has weak ability to sense stationary objects.

▪  Microwave Radar works based on the Doppler effect and usually emits high-frequency microwave signals (the 24GHz frequency band is common).

The sensor continuously transmits microwaves. When a moving object (such as a pedestrian) appears within the sensing range, the frequency of the reflected microwaves will shift.

The sensor captures the frequency-shifted signal, identifies the presence of a moving object, and triggers the door to open.

Essentially, it detects "the moving speed of objects", is sensitive to moving targets, and the induction sensitivity of some models can be adjusted.

II. Comparison of Core Performance and Applicable Scenarios

▪  Induction Targets. Infrared Radar prioritizes objects that can reflect infrared rays. Microwave Radar prioritizes moving objects, unaffected by object material and color.

▪  Anti-interference Capability. Infrared Radar susceptible to strong light (e.g., direct sunlight), dust and fog. Microwave Radar possess the strong resistance to strong light, dust and fog,not affected by ambient light.

▪  False Trigger Probability. Infrared Radar prone to false triggering under strong light, almost no triggering for stationary objects. Microwave Radar prone to false triggering by small, fast-moving objects (e.g., fluttering plastic bags).

▪  Applicable Scenarios. Infrared Radar suitable for indoor light-shielded environments (like office building interior doors). Microwave Radar suitable for universal for indoor and outdoor use (like shopping mall entrances, hotel gates, garage entrances and exits)

▪  Power Consumption & Cost.  Infrared Radar with Low power consumption, relatively low cost. Microwave Radar with slightly higher power consumption, moderately higher cost .

III. Practical Application Notes

▪  Infrared Sensing Radar. Suitable for indoor environments without direct strong light. During installation, keep it away from strong infrared light sources such as windows and spotlights.

For objects with light-absorbing surfaces (e.g., people wearing dark clothes), the sensing distance may be shortened, so the sensing range needs to be adjusted according to the scenario.

▪  Microwave Radar. When installed outdoors, it is recommended to be equipped with a false trigger prevention adjustment function to avoid door opening triggered by wind-blown debris and fast-moving vehicles.

Some high-sensitivity models can detect slow-moving objects (such as the elderly and children), making them more suitable for public places with heavy pedestrian traffic.