The word radar is a made-up, compound word and stands for ‘RAdio Detection And Ranging’. The phrase describes the meaning of radar as a radio-wave-based measurement method for detection and positioning. A radar unit is meant to detect and locate static and moving objects and consists of a transceiver (compound word made up of transmitter & receiver), which in turn is made up of one or several antennas that actively transmit and receive signals.

Important scientific discoveries

In 1886, Heinrich Hertz proved the existence and effect of radio waves for the first time, thus confirming the theory of electromagnetic radiation as described by James Clark Maxwell. Christian Hülsmeyer then carried out the first radar positioning tests in 1904. In doing so, he measured the time required for the waves to be reflected by a metallic object. He then patented the method and is considered the inventor of radar. In 1842, Christian Doppler developed the theory of the Doppler effect to detect objects’ movements.

These scientific findings laid the foundation for the development and use of radar sensors. The technology achieved a worldwide breakthrough through its military and nautical use in positioning air and sea targets in the 1930s.

Bionics – copied from nature

Radar detection works in a similarly to the biosonar of animals. Bats and dolphins use echolocation to find food and navigate dark habitats. For this purpose, they emit a sound in a given frequency (a wave-like, continuous vibration), which is reflected upon hitting an object. The animals then orient themselves using the echo.

The measuring principle

Radar is an active radio measurement method that communicates within the frequency range of 30 megahertz to about 300 gigahertz. The antenna of the radar unit emits a focused, short or continuous microwave pulse in a specific direction. The signal spreads out at the speed of light with its given transmission energy. If it hits an object on its way, part of the energy changes. The reflection of the signal is then received by the radar’s receiving antenna. The resulting response signal contains important object information which can be interpreted and analysed based on the signal change.

Radar measurement properties

The operating principle entails some useful properties. Radar doesn’t require direct contact with the object being detected and is therefore a non-contact measuring method. The radar waves are not noticeable to humans and are not harmful to health provided that international rules and regulations are complied with.

Radar technology does not produce a visual image that could be used to identify a person, meaning it ensures anonymity. Because radar waves utilise a different spectrum than light, this sensor technology also works at night. Glare from the sun being low in the sky doesn’t cause any problems either. The technology is generally considered to be weather-resistant, as it works reliably in extreme temperatures, snow, rain, or other weather phenomena.

When radar waves hit an object, they penetrate the material or are reflected or absorbed. It is thus possible to conceal radar sensors behind a plastic cover, for instance. This measuring method recognises not only objects or vehicles but also people, animals, and plants – regardless of whether they are moving or standing still. Fluids are also detectable.

What information does radar detect?

Depending on how radar equipment is deployed, the following data about objects can be obtained with radar sensors:

• presence of objects
• motion detection
• object distance to radar
• direction of movement
• speed
• angular position

Based on this information, high-resolution systems can also be used to measure contours for recording the environment. When combined with intelligent signal processing, this also enables object tracking – radar tracking – as well as classification.

Radar applications

This sensor technology has a wide range of capabilities and can thus be used widely – including in the industrial and commercial sector. We frequently rely on this technology – both at work and in our day-to-day lives – more often than we think. It is used for motion-based control of indoor and outdoor lighting elements, detecting burglars, perimeter monitoring, as well as counting people and controlling access. Radar is also used to measure speeds at sport events and or in traffic. Automation technology in buildings, autonomous vehicles in industry, and the opening of doors/gates likewise utilise this measuring method. Another success of radar lies in its in-vehicle use – with radar-based driver assistance systems ensuring greater safety in road traffic.

Due to the continuous further development of radar, software, and chip technology, sensors’ capabilities are constantly improving in parallel, enabling new areas of application in a broad array of sectors.

InnoSenT – An Introduction into Radar

Information on this advanced sensor technology

The demand for sensors is increasing due to trends such as digitalisation, automation in industry & logistics, smart homes & cities, and autonomous driving. But the development and integration of radar units is a complex topic, and the technical terms and functions raise many questions for users. Our radar experts have put together comprehensive information to help you get started in the world of radar.