A Guide to Satellite Frequency Bands: L, S, C, X, Ku, Ka

Everyone in satellite communications talks in band letters — "it's a Ku-band payload," "we're moving to Ka." Here's what those letters actually mean, and where they come from.

A naming convention, not a legal category

It's worth saying plainly: the letter-band names (L, S, C, X, Ku, Ka, and others) are an informal engineering convention, popularized through IEEE usage — they are not how the ITU itself defines frequency allocations. The Radio Regulations allocate spectrum by specific frequency ranges and services in the Table of Frequency Allocations, band letters are just industry shorthand layered on top for convenience. That's also why you'll sometimes see slightly different boundary numbers quoted for the "same" band across sources — the letters were never meant to be precise legal boundaries.

The bands, roughly

Band	Roughly	Typically used for
L	1–2 GHz	Mobile-satellite services, GPS and other GNSS signals
S	2–4 GHz	Some mobile-satellite services, weather radar, certain TT&C links
C	4–8 GHz	Classic fixed-satellite service — resistant to rain fade, long-established VSAT and broadcast feeds
X	8–12 GHz	Primarily government and military satellite communications
Ku	12–18 GHz	Broadcast satellite services, VSAT, DTH television — more rain fade than C-band
Ka	26.5–40 GHz	High-throughput satellites and newer NGSO broadband constellations — most rain-fade sensitive of the common bands, but far more available bandwidth

Why this matters for filing and screening

Band choice shapes almost everything downstream: how crowded the coordination landscape already is (C and Ku bands have decades of legacy GSO filings; Ka is where most new NGSO broadband capacity is being claimed), how sensitive the link is to weather, and what kind of ground equipment is practical. When you're screening for interference, knowing which band convention a candidate filing sits in gives you a fast, informal sense of how contested that part of the spectrum already is — before you even look at the exact frequency numbers.