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Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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Radio Electromagnetic Spectrum Frequency Bands

Radio Electromagnetic Spectrum Frequency Band Chart - RF Cafe

This chart shows the relative positions of the most common frequency bands, and is not to scale.

ELF = Extremely Low Frequency

VF = Voice Frequency

VLF = Very Low Frequency

LF = Low Frequency

MF = Medium Frequency

HF = High Frequency

VHF = Very High Frequency

UHF = Ultra High Frequency

SHF = Super High Frequency

EHF = Extremely High Frequency


January 2022 Update:

In response to my solicitation for information on the origin of band letter designations, a website visitor offered this:

I just looked at your web page that gives the names of the various RF bands, and, in one place asked for any information on origins of the names. I have some history on the band names that apply to UHF and above.

In the early days of radar (during WWII), the British and the U.S. researchers at MIT chose, arbitrarily I believe, letter designations for radar frequencies. The frequencies that were then possible to use for radio communication were just called by their "meter range" names: HF, VHF and UHF. The new frequencies that were then only used for deployable radar sets, and for new technology looking for even shorter wavelength radars, were given letter designations. So, in the 1940s and 1950s, radar sets were identified as being UHF, L-Band, S-Band, C-Band, X-Band and K-Band. Later they added Ku-Band - presumably for "K Upper," but I do not know. Later these became expanded with additional names for segments of spectrum, usually by the researchers or by their company marketing departments. I do not think the letters had any relational meaning - possibly this was a mild security measure. It seems unlikely that "Kurz" (German for "short") was any part of it since at the time the Germans were the enemy.

But there was an entirely separate community that also named segments of this same spectrum. This was the electronic warfare/electronic countermeasures researchers, companies and their military operators, and development and procurement agencies. They completely ignored "those radar guys" and invented their own spectrum segment designations. These segments were designated by letters in alphabetic order; starting with "A Band" at the low end and going upward with frequency. Some of the designators on your web pages are derived from this naming set. The band letter designators were physically implemented on the front panel band switches on ECM/ECCM sets. At least that was the case for USAF sets where the Air Force "EWO" (Electronic Warfare Officer) types used these letter designations exclusively and did not know what anyone meant if they used the "radar" band designations.

The "decade meter range" names were generally understood by everyone, but were treated as a broad generalization. The communications people were the custodians and protectors of these designations. (ULF, VLF, LF, MF, HF, VHF, UHF, etc.)

The "radar" bands are presently called "radar designations." The communications "decade/meter" names are called "the ITU designations," and the electronic warfare (EW) band names are called "the IEEE designations."

If you do a search on the origin of the designations for the various frequency bands, what you will find that nobody really knows. I have seen some pretty bogus explanations for how the band designation came to be, but I seriously doubt that the letters were assigned in order to confuse the enemy during WWII, or that "X" band was named for "cross," like in the cross hairs of precision targeting radars.

There is some logic in the upper and lower frequencies of the bands, however. The "3x10n" frequencies derive from wavelength in meters. Recalling that the speed of light in air is 300,000 km/s, that means a 1 meter wavelength translates to a frequency of 300 MHz, 10 meters is 30 MHz, 100 meters is 3 MHz, etc.

At some point, some wise soul decided that it was time to start over at a single digit for L-band at 1 GHz. The new regions are in octaves, except for 3 GHz, to 8 GHz. If anyone knows why 12.5, 18, and 26.5 GHz band edges were chosen, I would appreciate your letting me know.

Regarding the Ku, K, and Ka bands, supposedly K was named after the German word for "short," as in shortwave - Kurz. Ku is supposedly for K-under and Ka is supposedly K-above. That, of course, is inconsistent since since the K, if is derives from Kurz in wavelength, so K-under would be a lower (lesser) wavelength (hence higher frequency) and K-above would be a longer (greater) wavelength (hence lower frequency). Mostly likely, the certain origins are buried with their progenitors.

  • High Level Divisions in Frequency Band Designations:

    • Extremely low-frequency (ELF) band: 30 Hz to 300 Hz (10 megameter down to 1 megameter)
    • Voice-frequency (VF) band: 300 Hz to 3 kHz (1 megameter to 100 kilometer)
    • Very low-frequency (VLF) band: 3 kHz to 30 kHz (100 km to 10 km)
    • Low-frequency (LF) band: 30 kHz to 300 kHz (10 km to 1 km)
    • Medium-frequency (MF) band: 300 kHz to 3 MHz (1 km to 100 m)
    • High-frequency (HF) band: 3 MHz to 30 MHz (100 m to 10 m)
    • Very high-frequency (VHF) band: 30 MHz to 300 MHz (10 m down to 1 m)
    • Ultra high-frequency (UHF) band: 300 MHz to 3 GHz (1 m to 10 cm)
    • Super high-frequency (SHF) band: 3 GHz to 30 GHz (1 cm to 1 cm)
    • Extremely high-frequency (EHF) band: 30 GHz to 300 GHz (1 cm down to 1 mm)
  • Widely Accepted Lettered Frequency Band Designations:

    • L band: 1 GHz to 2 GHz (30 cm to 15 cm)
    • S band: 2 GHz to 4 GHz (15 cm to 7.5 cm)
    • C band: 4 GHz to 8 GHz (7.5 cm to 3.75 cm)
    • X band: 8 GHz to 12 GHz (3.75 cm to 2.5 cm )
    • Ku band: 12 GHz to 18 GHz (2.5 cm to 1.67 cm)
    • K band: 18 GHz to 26.5 GHz (1.67 cm to 1.13 cm)
    • Ka band: 26.5 GHz to 40 GHz (1.13 cm to 7.5 mm)
    • Q band: 32 GHz to 50 GHz (9.38 mm to 6 mm)
    • U band: 40 GHz to 60 GHz (7.5 mm to 5 mm)
    • V band: 50 GHz to 75 GHz (6 mm to 4 mm)
    • W band: 75 GHz to 100 GHz (4 mm to 3.33 mm)
  • Alternate Lettered Frequency Band (UHF, SHF, EHF) Designations:

    • L band: 1.12 GHz to 1.7 GHz (26.8 cm to 17.6 cm)
    • LS band: 1.7 GHz to 2.6 GHz (17.6 cm to 11.5 cm)
    • S band: 2.6 GHz to 3.95 GHz (11.5 cm to 7.59 cm)
    • C (G) band: 3.95 GHz to 5.85 GHz (7.59 cm to 5.13 cm)
    • XN (J, XC) band: 5.85 GHz to 8.2 GHz (5.13 cm to 3.66 cm)
    • XB (H, BL) band: 7.05 GHz to 10 GHz (4.26 cm to 3 cm)
    • X band: 8.2 GHz to 12.4 GHz (3.66 cm to 2.42 cm)
    • Ku (P) band: 12.4 GHz to 18 GHz (2.42 cm to 1.67 cm)
    • K band: 18 GHz to 26.5 GHz (1.67 cm to 1.13 cm)
    • V (R, Ka) band: 26.5 GHz to 40 GHz (1.13 cm to 7.5 mm)
    • Q (V) band: 33 GHz to 50 GHz (9.09 mm to 6 mm)
    • M (W) band: 50 GHz to 75 GHz (6 mm to 4 mm)
    • E (Y) band: 60 GHz to 90 GHz (5 mm to 3.33 mm)
    • F (N) band: 90 GHz to 140 GHz (3.33 mm to 2.14 mm)
    • G (A) band: 140 GHz to 220 GHz (2.14 mm to 1.36 mm)
    • R band: 220 GHz to 325 GHz (1.36 mm to 0.923 mm)
  • Subdivided Lettered Frequency Band (VHF, UHF, SHF, EHF) Designations:

    • A band: 100 MHz to 250 MHz (3 m to 1.2 m)
    • B band: 250 MHz to 500 MHz (1.2 m to 60 cm)
    • C band: 500 MHz to 1 GHz (60 cm to 30 cm)
    • D band: 1 GHz to 2 GHz (30 cm to 15 cm)
    • E band: 2 GHz to 3 GHz (15 cm to 10 cm)
    • F band: 3 GHz to 4 GHz (10 cm to 7.5 cm)
    • G band: 4 GHz to 6 GHz (7.5 cm to 5 cm)
    • H band: 6 GHz to 8 GHz (5 cm to 3.75 cm)
    • I band: 8 GHz to 10 GHz (3.75 cm to 3 cm)
    • J band: 10 GHz to 20 GHz (3 cm to 1.5 cm)
    • K band: 20 GHz to 40 GHz (1.5 cm to 7.5 mm)
    • L band: 40 GHz to 60 GHz (7.5 mm to 5 mm)
    • M band: 60 GHz to 100 GHz (5 mm to 3 mm)
  • Commercial Broadcast Bands:

    • Longwave Radio: 150 – 290 kHz

    • AM Radio: 550 – 1640 kHz (1.640 MHz) (107 Channels, 10-kHz separation)

    • International Radio: 3 – 30 MHz

    • Shortwave Radio: 5.95 – 26.1 MHz (8 bands)

    • VHF Television (channels 2 – 4): 54 – 72 MHz

    • VHF Television (channels 5 – 6): 76 – 88 MHz

    • FM Radio: 88 – 108 MHz

    • VHF Television (channels 7 – 13): 174 – 216 MHz

    • UHF Television (channels 14 – 83): 470 – 890 MHz

 

 

Posted February 22, 2018 (update)

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