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HomeTopicsShortwave BasicsShortwave Frequencies
Shortwave FrequenciesShortwave bands certainly took the world by surprise when they first came out in the early 1920s. A little after World War I, amateur radio enthusiasts began to test communication using wavelengths shorter than what was legal. Eventually, the amateurs stumbled across a revolutionary new way of transmitting wavelengths.
Not only were shortwave frequencies capable of traveling long distances, but shortwave frequency transmitters and receivers were cheaper to produce than the long wave versions. Now, we use shortwave radio frequencies to our benefit through international broadcasting, marine communication and worldwide amateur radio.
What is Shortwave FrequencyBecause frequency and wavelengths are inversely related, a shortwave frequency has a high frequency. For shortwave radio frequencies, this is any frequency between 3 MHz to 30 MHz. To gain a better understanding of shortwave radio frequency, let's compare shortwave radio frequencies with other broadcasting frequencies:
As you can see, shortwave radio frequencies are closely related to AM radio, which uses medium wave frequencies. Shortwave frequencies can be heard on any AM receiver.
The main appeal of world shortwave frequencies is their ability for long-distance broadcasting, paving the way to worldwide communication. Due to a phenomenon known as the Skywave propagation, shortwave radio frequencies can reach global locations through refraction from the ionosphere (a layer of the Earth's atmosphere).
Factors that Affect Shortwave Radio FrequenciesWhile shortwave frequencies make global communication possible, they do have a few issues that have yet to be resolved. Certain factors that affect the quality of transmissions are:
The greater the distance between the transmitter and the receiver, the more likely the transmission will suffer.
During the day, an atmospheric layer forms that is responsible for absorbing frequencies. Because of this (a factor known as the "D Layer"), transmissions sent at a frequency higher than 12 MHz travel longer in daylight. In the night, the opposite is true (lower frequencies will travel farther).
For the same reason mentioned above, sunnier seasons also are best for shortwave radio frequencies.
Accountable for refracting shortwave frequencies, the ionosphere is sensitive to sun activity. Any solar flares or sunspots could affect shortwave frequency transmissions.
Using World Shortwave FrequenciesWith a connecting capability like global communication, shortwave frequencies have a versatility that lends itself to a variety of audiences. Some well-known uses are international broadcasting and amateur radio. In fact, amateur radio operators have even coined the term "DXing" to refer to communication using shortwave frequencies.
Utility stations are finding shortwave frequencies useful for sending messages to a specific audience, such as aviators, military and merchant shippers.
Some musicians are even experimenting with shortwave radio, from using them as instruments to incorporating recorded broadcasts. These musicians include Peter Gabriel, Rush and Wilco. |
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