|RF Propagation Characteristics by Frequency Band|
The following is a quick reference page describing RF wave behavior broken down by frequency
All RF Bands
VLF (Very Low Frequency)
3 – 30 kHz
The earth and the ionosphere acts as a wave-guide. Used in submarine communications.
LF (Low Frequency)
30 – 300 kHz
Waves can travel through the surface of large objects like the earth as the earth acts as a conductor. Ionospheric effects can cause interference.
MF (Medium Frequency)
0.3 – 3 MHz
|Same as above, but with less penetration of objects|
HF (High Frequency)
3 – 30 MHz
Ionospheric propagation is available, so very long distance communication is possible. Much interference and fading is experienced through the shifting of the ionospheric layers and solar activity.
VHF (Very High Frequency)
30 – 300 MHz
Ionospheric waves can be neglected (except for interference). Lower VHF frequencies can adapt somewhat to the terrain, so communication over distances of 100 km is possible. At the higher VHF and all UHF frequencies, communication is possible mainly in strictly line of sight conditions. Rain is generally not a problem
UHF (Ultra High Frequency)
0.3 – 3 GHz
SHF (Super High Frequency)
3 – 30 GHz
|Over longer distances than 10kms rain, obstacles, and atmospheric attenuation become serious problems here.|
EHF (Extremely High Frequency)
30 – 300 GHz
0.1– 1000 GHz
Not capable of penetrating walls and other opaque objects or media such as dense fog or rain. This communication is weakened by strong light on the transmitter.
Microwave Bands and Higher
Common Band Designator
1 - 2 GHz
Effectively no rain attenuation but the ionosphere can introduce a rapid fading called ionospheric scintillation. This band represents a regulatory challenge and not a technical one. There are more uses and users for this spectrum than there is spectrum available. Additional spectrum for satellite communications will be opened up as terrestrial users are migrated out to other frequencies.
2 - 4 GHz
Inherently low background noise level and suffers less from ionospheric effects than L band.
4 - 8 GHz
This is the most heavily developed and used piece of the satellite spectrum. Service characteristics are excellent because of modest amount of fading from rain and ionospheric scintillation. The large size earth station antenna is a drawback.
8 - 12.5 GHz
Military usage dominates. X band can provide service quality on par with C band, but commercial users will find the equipment costs to be higher due to the thinner market.
"Ku " Band
12.5 - 18 GHz
Spectrum allocations here are more plentiful than in C band. Digital Direct To Home (DTH) services such as DirecTV use this band. VSATs and DTH receivers must anticipate more rain attenuation, but this can be countered by increasing satellite radiated transmission power.
18 - 26.5 GHz
26.5 - 40 GHz
From a technical standpoint, Ka band has many challenges. The biggest is the heavy attenuation due to rainfall. Spectrum is abundant in this band and new services opt for this band for this reason and the high data bandwidths that it promises.