One of the most recent and important trends in the satellite industry is the development of Ka-band. As the C and Ku bandwidths grow increasingly congested, interest in Ka band for commercial satellite communications has increased globally, and at Norsat we’ve been staying ahead of the trend with new Ka-band product development.
A Bit of Ka-Band History
Early Ka research started in the 1970’s, followed by NASA (ACTS) in 1993. However, development of Ka-band satellites slowed and by 2003 there only a few in orbit. In 1990’s, as part of a Department of Communications initiative to investigate Ka-band satellite communications in Canada, a small group of engineers and scientists recommended the development of a satellite communications system based upon Multi-Frequency, Time Division Multiple Access (MF TDMA). The Canadian Space Agency sponsored a joint government/industry initiative, AdvSat program, which evolved into a major hardware development program lasting from 1997 until 2000. Norsat was involved in the development of the MF TDMA concept, concentrating mainly on the complex Ka-band RF and antenna technologies emerging with the first to market products in that area.
In 1996, SES issued an RFP for the development of a commercial DVB-RCS hub and Norsat was the supplier of the terminal Outdoor Unit (ODU). A commercial contract was signed in 1998 and the full commercial hub was deployed in 2001. Around that same time EMS Technologies also secured the world’s first production sale of DVB-RCS terminals using Ka-band ODUs supplied by Norsat.
Back to the Future
Ka is now firmly in place with 419 satellites operating in this orbit (as of Jan 2012), covering the frequencies of 26.5–40 GHz, with LNB frequencies banded about varying from the 17.3 to 24.0 KHz ranges. Norsat chose to “standardize” the 18.2-21.2 GHz range in the LNBs and offer both the 29-30 and 30-31 range in BUCs, although we also do a lot of custom frequencies in LNBs, BDCs and LNAs below, above and within those ranges. With Wideband Global SatCom System (WGS), Norsat is currently working on LNBs & BUCs to fill in some of the blanks in specification requirements and frequencies and will offer a full range of products in the low power range, available in 2013. Don’t touch that dial!
Apart from our COTS and custom products, Norsat is currently working with several companies on special projects involving both BUCs and LNBs with very non-standard frequencies. One of these projects includes prototypes of the 5W & 10W BUCs and Duo PLL/External Reference LNBs.
Ka-band has several advantages, with perhaps the most significant being the 2-3 GHz increase in bandwidth, which is double available in Ku band and five times more than C band. Due to the smaller wavelength this also means that Ka-band components are typically smaller, leading to smaller antennas on the same-sized platform. The footprints for Ka-band spot beams can also be made smaller, facilitating frequency and re-use.
For your reference, Microwave frequency bands, as defined by the Radio Society of Great Britain (RSGB), are shown in the table below:
|L band||1 to 2 GHz||S band||2 to 4 GHz|
|C band||4 to 8 GHz||X band||8 to 12 GHz|
|Ku band||12 to 18 GHz||K band||18 to 26.5 GHz|
|Ka band||26.5 to 40 GHz||Q band||30 to 50 GHz|
|U band||40 to 60 GHz||V band||50 to 75 GHz|
|E band||60 to 90 GHz||W band||75 to 110 GHz|
|F band||90 to 140 GHz||D band||110 to 170 GHz|