2 meters

From Wikipedia, the free encyclopedia.

The 2 meter amateur radio band is a portion of the VHF radio spectrum, comprising frequencies stretching from 144.000 MHz to 148.000 MHz in ITU Regions 2 (North & South America plus Hawaii) and 3 (Asia and Oceania)[1] and from 144.000 to 146.000 MHz in ITU Region 1 (Europe, Africa, and Russia).[2][3] The license privileges of amateur radio operators include the use of frequencies within this band for telecommunication, usually conducted locally within a range of about 100 miles (160 km).

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[edit] Operating on 2 meters

Because it is local and reliable, and because the licensing requirements to transmit on the 2-meter band are easy to meet in many parts of the world[4], this band is one of the most popular non-HF ham bands. This popularity also means that it is also the most used band for local emergency communications efforts, such as providing communications between Red Cross shelters and local authorities[5].

Much of 2-meter FM operation uses a radio repeater, a radio receiver and transmitter that instantly retransmits a signal over a longer distance. Simple radios for FM repeater operation have become plentiful and inexpensive in recent years. A fully-functional FM transceiver and antenna can be obtained for under US$200.

[edit] DX

While 2 meters is best known as a local band, there are many opportunities for long distance (DX) communications. Occasionally, bending in the atmosphere's troposphere (ducting) can allow 2-meter signals to carry hundreds of miles. This is called a lift.

In rare cases, Sporadic E propagation can bring contacts well over a 1,000 miles (1,600 km). 2 meters is also utilized in conjunction with 70 cm (Mode B or V/U) on some amateur radio satellites, giving distances of up to around 3,000 miles (4,800 km) with a Low Earth Orbit satellite.

A set of 2 long Yagi antennas for the 2 meter band fed in phase to obtain more gain and narrow main lobe of radiation (WA6PY)

By speeding up Morse code using an audio tape recorder, or using a computer, very short bursts of signal can be bounced off the ionized gas trail of meteor showers allowing DX. This is often called Burst transmission.

Another phenomenon that produces upper atmosphere ionization suitable for 2M DXing are the auroras. Since the ionization persists much longer than meteor trails, regular audio signals can be used, but the constant movement of the ionized gas leads to heavy distortion of the signals causing the audio to sound 'ghostly' and whispered.

To communicate over the longest distances hams use moonbounce. This involves high power and good antennas to reflect the VHF signals off the moon. VHF signals normally escape the earth's atmosphere, so using the moon as a target is quite practical. Due to the delay of the signal traveling to the moon and back, a person transmitting may hear the end of his own transmission returning.

[edit] Links to 2m propagation sites

[edit] References

  1. ^ US Amateur Radio Frequency Allocations. http://www.arrl.org/FandES/field/regulations/allocate.html accessed 12 May 2008.
  2. ^ RSGB UK band plan. http://www.rsgb.org/spectrumforum/bandplans/RSGB%20Band%20Plan%20master.pdf or http://www.rsgb-spectrumforum.org.uk/Papers/RSGB%20Band%20Plan%20master.htm Accessed 14 May 2008.
  3. ^ Sharing spectrum with other services a ham radio reality. The ARRL Letter, Vol. 20, No. 2. http://www.arrl.org/arrlletter/01/1102/ Accessed 14 May 2008.
  4. ^ http://www.rsgb.org/getlicence/#foundation RSGB licensing guide
  5. ^ http://www.rsgb.org/emergency/ RSGB Radio Emergency & Public Service Communications website
Very high frequency (VHF) and ultra high frequency (UHF) amateur radio bands
VHF UHF
6 m 4 m 2 m 1.25 m 70 cm 33 cm 23 cm 13 cm
50 MHz 70 MHz 144 MHz 219–220 MHz 420 MHz 902 MHz 1.24 GHz 2.3–2.31 GHz
54 MHz 70.5 MHz 148 MHz 222–225 MHz 450 MHz 928 MHz 1.3 GHz 2.39–2.45 GHz


This is an extract from Wikipedia, the Free Encyclopedia
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