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INSAT 4

INSAT is unique in its design combining telecommunication, television and radio broadcasting and meteorological services on a single platform. The involvement of various users like Department of Telecommunication, Ministry of Information and Broadcasting. India Meteorological Department enabled proper tuning of INSAT system towards identified national developmental needs.

Launched in December 2005 by the European Ariane launch vehicle, INSAT-4A is positioned at 83ºE longitude along with GSAT-12. It carries 12 Ku-band 36 MHz bandwidth transponders employing 140 Watts Travelling Wave Tube Amplifiers (TWTAs) to provide an EIRP of 52 dBW at the edge of coverage polygon with footprint covering Indian mainland and 12 C-band 36 MHz bandwidth transponders to provide an EIRP of 39 dBW at the edge of coverage with expanded radiation patterns encompassing Indian geographical boundary and area beyond India in Southeast and Northwest regions.

Configured with payloads identical to that of INSAT-4A, INSAT-4B was launched onboard the European ARIANE-5 launch vehicle on March 12, 2007. INSAT-4B carries 12 Ku-band and 12 C-band transponders to provide an EIRP of 52 dBW and 39 dBW respectively. Two Transmit/Receive dual grid offset fed shaped beam reflectors of 2.2 m diameter for Ku-band and 2 m diameter for C-band are used. INSAT-4B has augmented the high power transponder capacity over India in Ku-band and over a wider region in C-band. INSAT-4B has been co-located with INSAT-3A at 93.5ºE longitude. Due to a power anomaly, the satellite was operating to half its capacity by 2013.

INSAT-4CR was launched on September 2, 2007 on GSLV from Sriharikota. INSAT-4CR with 12 high power Ku-band transponders with an EIRP of 51.5 dBW has been positioned at 74ºE longitude co-located with INSAT-3C and KALPANA-1. INSAT-4CR is the third satellite in INSAT-4 series. INSAT-4CR is designed to provide Direct-To-Home (DTH) television services, Video Picture Transmission (VPT) and Digital Satellite News Gathering (DSNG).