On the Imaging of Large Antenna Array Navigation Systems

Abstract

This contribution discusses the imaging of large antenna array navigation systems by means of nearfield measurements. Examples for such navigation systems are the instrument landing system (ILS) and the Doppler VHF omnidirectional radio range (DVOR). In this context imaging means the determination of individual array’s antenna’s amplitudes and phases with nearfield measurements and a corresponding prediction of the far field radiation characteristic according to required specifications of flight inspections. Nearfield measurement results of a large ILS antenna array are presented, and fundamentals are explained with numerical simulations. In particular, a simple simulation scheme allows the investigation of basic measurement requirements and errors that are essential for the later application. This work is part of the NAVANT-NG II (navaid antenna characterization – next generation) project dealing with nearfield inspection techniques by means of unmanned aerial vehicle. From the academic point of view this contribution summarizes the fundamental issues and probable approaches for solutions of such imaging techniques, which are a mathmatical ill-conditioned problem, that exceeds the current state of the art of nearfield inspection of single antennas.