In-Situ Monitoring Method for Direction Finding Antennas

Antenna arrays for direction finding (DF) are usually designed and tested in controlled environments such as anechoic chambers. However, antenna pattern may change significantly when antennas are placed in their operational environment. In such perturbing close context, the antennas calibration validity becomes a major issue which can lead to DF performance degradation and costly recalibration process. This paper presents an innovative design and implementation of a non-disturbing solution for quasi-real time antenna monitoring. The proposed system is based on optically modulated scattering (OMS) technique. Its capacity to detect the presence of various types of obstacles, which significantly perturb the antenna radiation pattern, is evaluated. A relation between monitoring mode and DF mode measurement signals is established. Finally, a design and sizing of the overall system is proposed.