Singapore

Frequency Allocations for the C-Band

In September, 2009, Singapore released the results of a study it had conducted on the coexistence of BWA (WiMAX) and FSS. There is little C-band usage in Singapore although Inmarsat does operate feeder link earth stations for its mobile-satellite service on Sentosa Island using the extended C-band. Using high elevation angles (65.5 – 87.5 degrees), a 3.1 m earth station antenna and 100 MHz frequency separation, Singapore came to the conclusion that typical BWA transmitters and FSS earth stations can be separated by as little as 200 m without excess interference into the FSS.

It should be noted that many applications use C-band earth station antennas with a diameter of less than 3.1 m and that a filter cannot always be inserted. The insertion of a filter decreases the G/T of the FSS earth station. Furthermore, the elevation angles used in the Singapore study are high. For FSS earth stations operating with satellites located lower on the horizon the elevation angles will be less and the separation of 200 m may not be sufficient since interference may now be received on the side lobe or even main lobe of the FSS earth station. The 100 MHz guard band is essentially sterilized since it can be used neither for FSS nor BWA.