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Radio: Difference between revisions
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→Wavelength calculation
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==== Wavelength calculation ==== | ==== Wavelength calculation ==== | ||
[[File:Wavelength-calculation.jpg|thumb]] | [[File:Wavelength-calculation.jpg|thumb|left]] | ||
If you know what frequency you need to tune into, you can calculate the full wavelength and build an antenna to match. The wavelength calculation is | If you know what frequency you need to tune into, you can calculate the full wavelength and build an antenna to match. The wavelength calculation is shown in the inline image. | ||
Here, 'v' is called the phase speed (magnitude of the phase velocity) of the wave and 'f' is the wave's frequency<ref>https://en.wikipedia.org/wiki/Wavelength</ref>. In the context of radio, 'v' is the speed of light, or 3×10<sup>8</sup> m/s (specifically 299,792,458 m/s). For instance, if the desired emergency broadcast station was at 1650kHz, the full wavelength would be 181.69m, and so a 1/4 wave of 45.42 meter (149 feet) or 1/2 wave antenna of 90.84 meter (298 feet) could be built. | Here, 'v' is called the phase speed (magnitude of the phase velocity) of the wave and 'f' is the wave's frequency<ref>https://en.wikipedia.org/wiki/Wavelength</ref>. In the context of radio, 'v' is the speed of light, or 3×10<sup>8</sup> m/s (specifically 299,792,458 m/s). For instance, if the desired emergency broadcast station was at 1650kHz, the full wavelength would be 181.69m, and so a 1/4 wave of 45.42 meter (149 feet) or 1/2 wave antenna of 90.84 meter (298 feet) could be built. | ||