Radar sensor technology and application areas

Radar stands for Radio Detection and Ranging and is an important and innovative technology in automation technology that is used for numerous applications in both hygienic and industrial environments.
Radar sensors emit electromagnetic waves, whose frequency ranges stretch from approx. 30 MHz to approx. 300 GHz, with the echoes reflected by objects or media serving as active transmission and reception method to calculate their distance to the sensor.

ifm radar sensors utilise the Frequency Modulated Continuous Wave (FMCW) method. They emit high-frequency electromagnetic waves with a periodically changing frequency. These waves are reflected by objects, detected by the sensor’s receiving antenna and evaluated. Based on the time offset between the transmitted and reflected signal, information on distance, speed, direction and position can be precisely determined.

The radar cross-section

The radar cross-section (RCS) is a measure of how well an object is detectable by radar, i.e. how much of the emitted energy is reflected from the object. The higher the RCS value, the greater the reflectivity and therefore the visibility of the object.

The RCS value depends on factors such as material, medium, size and angle of incidence, but not on the distance of the reflection target as long as a reflection is not affected by the distance. The higher the dielectric constant and the bigger the object size and circumference, the better the visibility.

Radar frequency and antenna size

The radar frequency and the antenna size of the sensor are two key factors that determine the aperture angle and therefore the range and precision of a radar sensor.
A small aperture angle enables strong signal focussing, which has a positive effect on the range and precision of the sensor. Moreover, this enables for example interfering structures in tanks to be suppressed.
Good to know:

• The smaller the antenna size, the larger the aperture angle at the same frequency.
• The higher the frequency, the smaller the aperture angle for the same antenna size.
• High frequencies enable compact designs due to the short wavelength.

Radar resolution

Radar resolution, also known as separability, describes a radar’s ability to clearly separate targets that are close to each other and output them as separate targets. In situations where targets differ only slightly in their measured values, there is a risk that they will merge into one target and not be detected individually.Basically, there are two types of radar resolution: