Editing Ku band (section)

==Advantages==
Compared with [[C band (IEEE)|C-band]], K<sub>u</sub> band is not similarly restricted in power to avoid interference with terrestrial microwave systems, and the power of its uplinks and downlinks can be increased.  This higher power also translates into smaller receiving dishes and points out a generalization between a satellite's transmission and a dish's size.  As the power increases, the size of an antenna's dish will decrease.<ref>{{cite book|last1=Mirabito|first1=M|last2=Morgenstern|first2=B|year=2004 |title=Satellites: Operations and Applications. The New Communication Technologies|edition=5|location=Burlington|publisher=Focal Press.|isbn=978-0240805863}}</ref>{{page needed|date=July 2016}} This is because the purpose of the dish element of the antenna is to collect the incident waves over an area and focus them all onto the antenna's actual receiving element, mounted in front of the dish (and pointed back towards its face); if the waves are more intense, fewer of them need to be collected to achieve the same intensity at the receiving element.

A major attraction of the band over lower frequency microwave bands is that the shorter wavelengths allow sufficient angular resolution to separate the signals of different communication satellites to be achieved with smaller terrestrial [[parabolic antenna]]s.   From the [[Angular resolution#The_Rayleigh_criterion|Rayleigh criterion]], the diameter of a parabolic dish required to create a radiation pattern with a given angular [[FWHM|beamwidth]] ([[antenna gain|gain]]) is proportional to the [[wavelength]], and thus inversely proportional to the frequency.   At 12&nbsp;GHz a 1-meter dish is capable of focusing on one satellite while sufficiently rejecting the signal from another satellite only 2 degrees away. This is important because satellites in FSS (Fixed Satellite Service) service (11.7-12.2&nbsp;GHz in the U.S.) are only 2 degrees apart.  At 4&nbsp;GHz (C-band) a 3-meter dish is required to achieve this narrow angular resolution.  Note the inverse linear correlation between dish size and frequency.  For K<sub>u</sub> satellites in DBS (Direct Broadcast Satellite) service (12.2-12.7&nbsp;GHz in the U.S.) dishes much smaller than 1-meter can be used because those satellites are spaced 9 degrees apart.  As power levels on both C and K<sub>u</sub> band satellites have increased over the years, dish beam-width has become much more critical than gain.

The K<sub>u</sub> band also offers a user more flexibility. A smaller dish size and a K<sub>u</sub> band system's freedom from terrestrial operations simplifies finding a suitable dish site. For the end users K<sub>u</sub> band is generally cheaper and enables smaller antennas (both because of the higher frequency and a more focused beam).<ref>[http://en.allexperts.com/q/Satellite-Communications-2436/Advantage-Disadvantages-1.htm Satellite Communications: Advantage and Disadvantages] {{webarchive|url=https://web.archive.org/web/20071023070212/http://en.allexperts.com/q/Satellite-Communications-2436/Advantage-Disadvantages-1.htm |date=2007-10-23 }}</ref> K<sub>u</sub> band is also less vulnerable to rain fade than the K<sub>a</sub> band frequency spectrum.