MMW Radar with Highest Resolution

The threat caused by new sensor development is increasing year by year. This is also true for techniques based on Radar. The exploitation of new, higher frequency bands gives Radar measurements with a high degree of details and very large range resolution. In this talk the MIRANDA-300 will be presented. The system was developed by Fraunhofer FHR for the WTD 81, Greding, to show the large benefits of very high resolution systems. It works in the frequency band of 300 GHz, which makes it possible to see objects concealed by clothes or tents. Although, in this frequency band explosives show neither a total transparency nor total reflection, which could make them observable on the one hand and give us the possibility to distinguish them from the human body, on the other hand. Tech nically, this high working frequency gives the possibility to gain a high absolute bandwidth of 40 GHz, which is a relative bandwidth of just 13%. So objects, which are parted just for 3.7 mm can be identified as two different targets. In this talk the system and the technical parameters will be presented. The MIRANDA-300 sensor is based on the MIRANDA-SAR 94 GHz FMCW radar. Using a signal generator developed at Fraunhofer FHR and based on DDS chips (direct digital synthesizer) frequency chirps with high linearity, low phase noise and a bandwidth of 1100 MHz are generated. Subsequently two different frequency multipliers are used to increase the signal frequency to 288 GHz. One key component for the system is the 300 GHz fundamental receiver chip of Fraunhofer IAF. Using this device the t ransmit power of less than 5 dBm (3 mW) is sufficient to measure objects in a range of up to 660 m. Additionally, ISAR (inverse synthetic aperture Radar) measurements will be shown, which have been gained using a turntable system. They show objects and persons in a range of 134 m with highest resolution and concealed objects like a mobile phone.