Ham radio operators have so many different operating modes and techniques in their tool chest; it is often hard to decide where to focus your attention. This will provide the reader with a short primer on operating characteristics in the VHF and UHF amateur radio bands. Amateurs who operate in the VHF and UHF region of the spectrum are often referred to as weak signal operators.

Most popular is the 2 meter band. This is because they are often pushing the envelope of capabilities in this region of the frequency spectrum and as such often are working with very weak signal strengths from other ham radio operators. To operate successfully in this environment hams normally turn to higher power stations, very sensitive receivers and much larger and higher antennas. In the VHF and UHF bands, the height of the antenna is critical as well as the gain of the antenna. Antennas in the VHF and UHF range used for weak signal communications are almost always YAGI antennas with many elements. These antennas can reach and often exceed 25 feet in length. They also are very directive in terms of signal strength, which means you need to be pointing the antenna in the geographical area in which you want to communicate. Pointing of the antenna is done many ways, some use what is called the “Arm-strong” method where you turn the antenna by hand, this is impractical in most cases however. Hams rely on rotators to both turn the antenna and know in what direction it is pointing.

For weak signal work most amateurs rely on either Single Side Band (SSB) or Continuous Wave (CW) modes. However, now with computers and specialized software available, hams are able to utilize what are known as digital modes to communicate using very weak signals. Using digital signal processing software, known as DSP, hams can communicate in instances where the human ear could not hear the signal, but the computer and software makes it possible to pull the signal right out of the noise!!!

So far we have discussed “terrestrial” communications on the VHF and UHF bands, meaning the signal was point to point between two ground stations. There are other modes used in the VHF/UHF region that go beyond just terrestrial communications. They are Earth-Moon-Earth or EME and Meteor scatter modes of operation. EME involves bouncing a signal off the Moon, and meteor scatter is reflecting the radio signals off the ionized trail from meteors entering the earth’s atmosphere! There are even hams radio satellites in orbit around the earth which hams use to communicate over long distances in the VHF/UHF bands. The satellite basically operates as a “repeater” in space, where the signal goes up to the satellite and is retransmitted to another ham well beyond normal line of sight for the VHF/UHF bands.

Amazing stuff is going on all time in the world of amateur radio, get involved today! Between choice of operating bands, weekly contests and working very distant exotic stations on the other side of the world, amateur radio remains an exciting hobby today.

Source by Joseph E Johnson

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