2-meter band

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) [US Amateur Radio Frequency Allocations. http://www.arrl.org/FandES/field/regulations/allocate.html accessed 12 May 2008.] and from 144.000 to 146.000 MHz in ITU Region 1 (Europe, Africa, and Russia). [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.] [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.] 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 convert|100|mi|km.

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 [http://www.rsgb.org/getlicence/#foundation RSGB licensing guide] , 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 [http://www.rsgb.org/emergency/ RSGB Radio Emergency & Public Service Communications website] .

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.

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 convert|1000|mi|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 convert|3000|mi|km with a Low Earth Orbit satellite.

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. Literally bouncing the VHF signals off the moon. VHF signals normally easily escapes the earth's atmosphere. Due to the delay of the signal travelling to the moon and back, a person transmitting may hear the end of his own transmission returning.

Links to 2m propagation sites

* [http://www.vhfdx.net/spots/map.php DX-Sherlock's real-time 2m propagation maps]
* [http://www.vhfdx.net/spots/map.php?Frec=TIC DX-Sherlock's real-time VHF&up propagation ticker]

References