Radar sensor technology and application areas
Find out more about the technology, operating principle and areas of application of radar sensors here.
Content
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.
Optimum performance even in demanding applicationsRadar technology is resistant to harsh environments due to difficult weather and temperature-related conditions and extraneous light. Thus, the measurement remains accurate at all times.
Overcoming long distancesAs radar waves propagate freely in air, objects or media can be detected over a long range. Depending on the type of application and sensor, the detection range can be up to 50 metres.
Penetrating different materialsThe electromagnetic waves emitted by a radar sensor can penetrate a wide variety of materials. Plastic in particular allows the sensor to be covered or encased without affecting the measurement results.
Non-contact technologyRadar allows for objects and media to be detected even at great distances without direct contact. Even properties such as the medium’s density, viscosity, temperature and pH do not impact the measurement.
Fast and preciseThe technology allows for fast, reliable and highly accurate measurements.
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:
Distance resolution
The bandwidth of the transmission signal determines the distance resolution, which enables the radar sensor to differentiate between objects based on their difference in distance.
Objects that are positioned at similar lateral and elevation angles to the radar can still reliably be separated by the radar based on their distance from each other. However, the distance resolution alone is not sufficient for precise localisation.
Angular resolution
The angular resolution describes the radar’s ability to differentiate between objects based on the information at which angle these targets are located to the radar. Angular resolution can be divided into azimuth resolution (lateral angles) and elevation resolution (elevation angles).
The aperture angle (field of view) of the radar antenna is an important factor in terms of angular resolution. The angle determination performance is considerably influenced by the number and design of the antennas.
Position determination
- Conveyor monitoring
- Vehicle positioning
- Distance control and height measurement
- Monitoring of surroundings and collision avoidance
- Smart access control
Hygienic level measurement
- in storage tanks as high as 10 m
- in mixing tanks with agitators
- in CIP tanks with spray balls
Industrial level measurement
- in storage tanks as high as 10 m
- in plastic tanks, e.g. IBC
- outdoor use
- flow rate measurement in Venturi flumes