Two dimensional BLI Array, Broadband BLR array panel & sectoral Horn BLI Array antenna

DRDO has develop a series of antennas for various applications, Kautilya is a spaceborne ELINT system payload for Satellite platform to intercept ground-based radars across the globe. The system provides high accuracy in direction finding and location fixing of radar transmissions. It has been successfully launched and being exploited.

Two-Dimensional BLI Array

Two-dimensional Base Line Interferometric (BLI) array consisting of spiral and pyramidal horn antennas as radiating elements has been realised for space-borne ELINT system. The spiral BLI array working in the C-D band, has 7 elements mounted in orthogonal axes, one being common for vertical and horizontal BLI arrays for DF in two orthogonal directions, i.e., elevation and azimuth.

The horn BLI array consists of four antennas mounted in slant 45⁰ with different inter-element spacing. The slant 45⁰ mounting enables the array to receive signals of both vertical and horizontal polarisation. Two such arrays, one vertically and another horizontally mounted , complete the 2–D BLI array subsystem. The vertical and the horizontal arrays give the angle of arrival in elevation and azimuth planes, respectively . Two sets of pyramidal horn arrays are employed to cover the E-G band and H-J band.

The surface of the horn antenna mounting bracket is covered with a magnetically loaded silicon rubber sheet to suppress surface currents and ensure smooth radiation patterns. All the material, components, and processes used in realising this 2-D array are space-qualified and have been subjected to stringent quality tests as per ISRO standards.