Introduction and Difference for Ka-band, Ku-band and L-band for LEO Tracking

The frequency band used for LEO tracking is various including Ka-band, Ku-band, L-band etc. The terms L-band, Ku and Ka satellites are universal quite freely. While do you really have an idea that what are they mean and the differences between them?

The band in use is the radio frequencies used to and from the satellite:

L-band frequencies in the 1 to 2GHz range
Ku-band 12-18GHz,
Ka-band 26.5-40GHz segment of the electromagnetic spectrum.

Ku is the lower part of the original NATO K band, which was divided into three bands (Ku, K, and Ka) for the presence of the atmospheric water vapour resonance peak at 22.24 GHz, (1.35 cm), which made the center unusable for long-range transmission.

Normally, the higher the frequency the more bandwidth you can squeeze out of the system. The difference is just like an FM radio broadcast being compared with medium wave. The higher frequency VHF radio (100MHz) band gives greater bandwidth than medium wave/AM (1MHz) and the sound quality is better.

Scale this up to the satellite’s microwave frequencies and Ka-band should give more digital bandwidth than Ku, which in turn should give greater bandwidth than L-band. But it is only half the story.

Physicist and mathematician developed what became famous as Shannon’s Theorem in 1948. This still true today and is a student essential to understanding satellite through puts. We’ll ignore the maths, but essentially it says:

The higher the bandwidth, the more data can be transferred
The higher the frequency the more bandwidth is available
A high signal-to-noise ratio is better
A raise in the transmit power level can give an increase in the communication link throughput.

So it isn’t just the matter of the frequency – you have to consider the power density available, and satellite spot beams provide a higher level generally, be it on Ku or Ka-band.

And the headline bandwidth figure usually represents the transponder bandwidth from the satellites.You also have to take a whole host of as other factors, such as how big is your antenna? What is the elevation of the satellite above the horizon? How many receivers are sharing the satellite’s spot beam at this time and even, what is the weather like? Yes, weather. Both Ku and Ka can suffer from rain fade (Ka more than Ku) – this is not usually a problem at 35,000 feet, but high levels of humidity in tropical areas can also affect signals.

The antenna used for tracking LEO is mostly adopting X/Y mount which will overcome the vertex tracking and with fast tracing speed.

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