DESIGN AND DEVELOPMENT OF A FOLIAGE PENETRATION RADAR ANTENNA

Abstract

A foliage penetration radar or FOPEN radar aids in surveillance of the forested area or any area covered in dense foliage. Requirement of the surveillance of a wide area cannot be fulfilled using a single antenna element. However, same can be achieved using an array of antenna, whose elements can be fed through a beam forming network or BFN. The main objective of this project is to design an antenna and a beam forming network which can cover an azimuth range of 5 km at a range of 4 km in C band. In this project, an 8 × 1 linear antenna array and an 8 × 5 two-dimensional antenna arrays have been designed using microstrip patch antenna which are fed through an 8 × 8 butler matrix which is a beam forming network. In linear array, the elevation beam width is very high which may lead to false detection of target other things as target, thus two dimensional antenna array has been designed to reduce the beam width in elevation plane as well. The experimental results of both the arrays have been compared in this project. The topology used for designing the butler matrix is different from the conventional topology, as the size of the conventional butler matrix is very big and insertion loss is also on the higher side. This topology has not been designed earlier in C band. The problems faced while designing it in C band have been addressed and solutions have been explained in detail. The design specifications of the antenna array and butler matrix have been explained in detail. The simulation results obtained shows that the requirement of the surveillance of an azimuth range of 5 km at a range of 4 km has been fulfilled with the design. The antenna array and the beam forming network designed in this project can also be used for other purposes also, for example, avalanche detection system, surveillance of the defence areas, border areas, vitals areas of national importance etc.