2-meter band

Occasionally, signal bending in the atmosphere's troposphere known as tropospheric ducting can allow 2 meter signals to carry hundreds or even thousands of kilometers as evidenced by the occasional 2 meter contact between the west coast of the United States and the Hawaiian Islands, the northeast region to the Florida coast, and across the Gulf of Mexico. These so-called "Openings" are generally first spotted by amateurs operating SSB (Single Side Band)[8] and CW (Continuous Wave)[9] modes since amateurs using these modes typically are attempting distance contacts (DX) and alert for signal enhancement events.

Completion of contacts using these weak signal modes involves the exchange of signal level reports and location by grid square which is known as the Maidenhead Locator System. Two way ducting contacts can have very strong signals and are often made with moderate power, small antennas, and other types of modes. Long distance ducting contacts do occur using FM modes as well but for the most part go unnoticed by many FM operators.

Another form of VHF propagation is called Sporadic E propagation. This is a phenomenon whereby radio signals are reflected back towards Earth by highly ionized segments of the ionosphere which can facilitate contacts in excess of 1,000 miles (1,600 km) with very strong signals received by both parties.

Unlike some other long distance modes, high power and large antennas are often not required to make contact with distant stations via a sporadic E event. A two-way conversation can take place over a distance of several hundred kilometers or more, often using low levels of RF power. Sporadic E is a rare and completely random propagation phenomenon lasting anywhere from a matter of minutes to several hours.

Satellites are basically repeater stations in orbit. The 2 meter band is also used in conjunction with the 70-centimeter band, or the 10-meter band and various microwave bands via orbiting amateur radio satellites. This is known as cross band repeating. On-board software defines what mode or band is in use at any particular time and this is determined by amateurs at so-called earth stations who control or instruct the satellite behavior. Amateurs know what mode is in use via published internet schedules.

For instance, a favorite mode is Mode "B" or "V/U" which simply indicates the uplink and downlink frequencies or bands the satellite is currently using. In this example, V/U means VHF/UHF or VHF uplink with UHF downlink. Most amateur satellites are Low Earth Orbit satellites, or LEO's as they are affectionately known, and generally are at about 450 miles (700 km) altitude. At that height, amateurs can expect reception distances of up to around 3,000 miles (4,800 km).

A few amateur satellites have very high elliptical orbits. These satellites can reach altitudes of 30,000 miles (50,000 km) above the earth where an entire hemisphere is visible providing outstanding communications capabilities from any two points on the earth within line of sight of the satellite; distances that are far beyond the reach of the LEOs.

Transequatorial propagation, also known as (TEP), is a regular daytime occurrence on the 2 meter band over the equatorial regions and is common in the temperate latitudes in late spring, early summer and, to a lesser degree, in early winter. For receiving stations located within ± 10 degrees of the geomagnetic equator, equatorial E-skip can be expected on most days throughout the year, peaking around midday local time.

By speeding up Morse code using analog tape or digital modes such as JT6M or FSK441, very short high-speed bursts of digital data can be bounced off the ionized gas trail of meteor showers. The speed required to confirm a two way contact via a short lived ionized meteor trail can only be performed by fast computers on both ends with very little human interaction.

One computer will send a request for contact and if successfully received by a distant station, a reply will be sent by the receiving stations computer usually via the same ionized meteor trail to confirm the contact. If nothing is received after the request, a new request is transmitted. This continues until a reply is received to confirm the contact or until no contact can be made and no new requests are sent. Using this high speed digital mode, a full two way contact, can be completed in one second or less and can only be validated using a computer. Depending on the intensity of the ionized meteor trail, multiple contacts from multiple stations can be made off the same trail until it dissipates and can no longer reflect VHF signals with sufficient strength. This mode is often called burst transmission and can yield communication distances similar to sporadic E as described above.

Another phenomenon that produces upper atmosphere ionization suitable for 2-meter DXing are the auroras. Since the ionization persists much longer than meteor trails, voice modulated radio signals may sometimes 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. In most instances using auroral reflections on 2 meters, audio or voice is totally unintelligible and ham operators wishing to make contacts via aurora, must resort to CW (Morse code).

CW signals returning from an auroral reflection have no distinct sound or tone but simply sound like a swishing or whooshing noise. An exception to this phenomenon would be the 6 meter band which is significantly lower in frequency than the 2 meter band by 94 MHz. In many instances 6 meter voice modes are readable but with varying degrees of difficulty when reflected off an aurora. Therefore, when using an auroral event as a radio signal reflector, the reflected signal strength and signal intelligibility decreases with increasing transmitting frequency.

To communicate over the longest distances, hams use moon bounce. VHF signals normally escape the Earth's atmosphere, so using the moon as a target is quite practical. Due to the distance involved and the very high path loss getting a readable signal bounced off the moon involves high power ~1,000 Watts and steerable high gain antennas. Receiving these very weak return signals, again involves the use of high gain antennas (usually the same type used to transmit the signal) and a very low-noise front end RF amplifier and a frequency stable receiver.

However, new and recent technological advances in weak signal detection has allowed the successful reception of signals off the moon using much smaller or less well equipped stations allowing reception of signals that are "in the noise" and not audible to the human ear. One of these modes is JT65 which is a digital mode. Due to the delay of the signal traveling to the moon and back (travel time approx. 2.5 seconds), a person transmitting may hear the end of their own transmission returning.[10]

The Irish Radio Transmitters Society has provided a series of awards for the first successful all-natural, non-bounce contacts on 2 metres between the North American and European continents. Named for Saint Brendan of Clonfert, the three awards differentiate between successful "traditional" phone/CW contact (the Brendan Trophies), successful "non-traditional" digital two-way contact (the Brendan Shields), and an award for the first verified reception in either direction, regardless of method (the Brendan Plates).[11] Attempts at the Brendan awards have established contact, but further examination revealed the signal was bounced off the International Space Station.[12]