Miniaturized high resolution Synthetic Aperture Radar at 94 GHz for microlite aircraft or UAV

A miniaturised millimetre wave radar, MIRANDA, to be used as Synthetic Aperture Radar onboard a small UAV was designed, built and tested onboard a microlite aircraft and an unmanned helicopter. The design followed the FM-CW principle, to get the highest possible average transmit power and thus the best range performance. A very flexible principle of operation, based upon multiplication of principle frequencies allowed a very easy adaption of the band of operation between 35 GHz and 220 GHz. The experiments described here were conducted at a centre frequency of 94 GHz. An inertial system of high quality, based upon a fibre optic gyroscope maintained the necessary precision, to allow high resolution SAR imaging. The raw data are transmitted to the ground station using an ordinary analogue data link, where they are A/D converted, preprocessed and finally undergo a real-time SAR-focusing algorithm. Additionally to the quick-look processing the data are stored to be able to apply further high quality SAR processing. The paper describes the design principles and gives results from the flight tests.