Radiation pattern of the antenna of a 24 GHz and an 80 GHz FMCW Radar Level Transmitter

Radiation pattern of the antenna: The radiation pattern of a radar system results from the combination of the frequency and the antenna diameter. In general, the following applies: With the same antenna diameter, the beam angle decreases proportionally when increasing the frequency. At the same frequency, the beam angle decreases proportionally when increasing the antenna diameter. The illuminated circles in the video illustrate the areas detected by the respective radar system on the product surface. It should be noted that radar beams spread out conically from the antenna. For the selected system configurations 24GHz with an 80mm horn antenna and 80GHz with a 40mm lens antenna, these areas are approximately identical. In this comparison, the radar beam can be demonstrated by using metal rings. In both systems, the radar beam travels through the ring opening. As a result, the rings are hardly visible in the reception signal. If the ring opening is reduced, the radar beam hits the metal surface and the ring is clearly visible in the received radar signal. If such a disturbance is caused, for example, by installations in tanks, there are two possibilities for optimization: Firstly, the disturbance can be hidden by recording an empty spectrum. For this purpose, the received radar signal of the empty tank is recorded and stored into the memory of the radar device and then subtracted from each subsequent measurement. However, the energy reflected at the rings means a reduction of the residual energy for the actual measurement of the product surface. Second, the use of a larger antenna can reduce the beam angle. This results in the following advantages: The radar beam angle no longer touches the ring surface, The complete energy radar signal is available for surface detection. Even with the 24GHz system, an increase in the antenna diameter would achieve a similar effect, but a significantly larger antenna would be necessary. Watch the whole video: https://www.youtube.com/watch?v=ydJYsOaOe3I