RF Bands overview

RA allows antennas to use different radio frequency bands. These different bands have different properties, which makes them useful for different applications. As a general rule, the lower frequency a radio signal, the less it will attenuate, and can be used at longer ranges. However, higher frequencies are more easily focused by radio dishes, and as such ground based radio stations and dish antennas get much better range at higher frequencies, despite the attenuation penalties.

• VHF: VHF is a starting tech, and defined as 150 MHz. This band has enough range to be used out to the moon, but not much beyond. The low frequency means only a small amount of data can be transmitted, and only omni antennas can be effectively used. As the lowest frequency, it is good for omni-to-omni communications. VHF at tech level one can be expected to get ~13 bits/s, and at max tech level 6.3 kb/s. It was used for short range ship-to-ship communication during the Apollo program.

• UHF: UHF is a starting tech, and defined as 430 MHz. This band is similar to VHF, but has better ground stations allowing for slightly longer range. The higher frequency means larger amounts of data can be transmitted. UHF at tech level one can be expected to get ~50 bits/s, and at max tech level 25 kb/s. It was used as the main method of communication for most early spacecraft, and is still used to this day as backup communications on many spacecraft.

RF Bands beyond this frequency are only received by the 3 DSN stations. Communications may be intermittent in low orbit

• S-Band: S-band is unlocked at tech level 3, and defined as 2.25 GHz. This will be your main radio band for deep space probes, as it will focus well with dishes, and uses the very powerful antennas of the DSN rather than the smaller antennas of the local ground stations. The high frequency allows for moderate bitrates. S-band at max tech level will achieve 330 kb/s. It is was used as the main communications of most spacecraft from the 60s until the late 70s, and is still used as backup communications on some spacecraft.

• X-Band: X-band is unlocked at tech level 7, and is defined as 8.45 GHz. The next step up after S-band, it gets slightly better focusing from dishes, and consequently better effective range. The higher frequency allows for better bitrates. X-band can achieve a maximum bitrate of 1.36 Mb/s. It is used on most modern deep space probes.

• Ka-Band: Ka-band is unlocked at tech level 9, and is defined as 32 GHz. As the highest frequency radio band available, it focuses very well (in some cases too well, Ka-band dishes will have a very narrow beamwidth, requiring much more precise aiming). Due to the very high frequencies, Ka-band can achieve very high bitrates. Ka-band can achieve a maximum bitrate of 20 Mb/s. Ka-Band is typically used for modern communications satellites due to its high bitrate.