Realization of Planar Array Antenna for SAR Application using Brush Plating

Mechanical design of antenna has been carried out in order to cater for realization of 1.4m long micro strip feed line as a single component, eliminating deficiencies associated with RF interconnections on PCB based planar antenna. Selection of metal was done in such a way that it should be less prone to corrosion and sustained in a long way as well as low cost. The antenna patches, feed probes & micro strip feedline is made up of Al6061-T6. It is required to protect the exposed surfaces of feedline from corrosion and oxides formation, while maintaining surface electrical conductivity. Solderability of the feed line at connector feed locations is also required in order to form a good solder joint between connector and feed line. Keeping in view the size of feed line (1.4m X 0.3m X 0.002m) and also the cost involved in silver plating entire feed, a need of selective, local silver plating process is felt, which can improve the solderability of aluminum feed line at selective locations only and remaining area of feed line is chromated to provide required corrosion resistance and surface electrical conductivity. Brush silver plating process is evolved which has been recently developed, has been successfully used for doing selective plating on complex and difficult to handle job. It is successfully implemented to yield desired conductivity for RF use.