RF front end for UAS-aided flight inspection of airport surveillance radars

Flight inspection of radio-based terrestrial navigation systems is crucial for sufficient accuracy. Especially in proximity of wind turbines (WT), which have arisen in recent years due to government subsidies for renewable energies, flight inspections must be carried out. This causes problems that hinder the usage of conventional aircraft: Even rotorcraft (e.g. helicopters) require a certain amount of clearance to WTs and cannot measure within wind farms. To solve this problem, unmanned aerial systems (UAS), such as multicopters, are a promising approach. Beside the solution of the clearance problem, they also provide further benefits in terms of cost effectiveness and flexibility; but on the downside they have limited payload. Since commercial off-the-shelf (COTS) test receivers exceed the UAS's loading capabilities, we developed a weight- and size-optimized test receiver that can compete with full-compliance measurement COTS devices. This has been achieved by focusing on the demands regarding carrier frequency and bandwidth of the system under test (SUT). In this paper we describe the RF front end for the reception of the forward scatter emitted by the airport surveillance radar (ASR) and show the first measurement results.