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In radio engineering and telecommunications, standing wave ratio (SWR) is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide. Impedance mismatches result in standing waves along the transmission line, and SWR is defined as the ratio of the partial standing wave 's amplitude at an ...
Radio amateurs may engage in satellite and space craft communications; however, the frequencies allowed for such activities are allocated separately from more general use radio amateur bands. Under the International Telecommunication Union 's rules, all amateur radio operations may only occur within 50 kilometres (31 mi) of the Earth's surface.
English: United States radio spectrum frequency allocations chart as of January 2016. Date: 31 January 2016: Source:
An SWR meter does not measure the actual impedance of a load (the resistance and reactance), but only the mismatch ratio. To measure the actual impedance requires an antenna analyzer or other similar RF measuring device. For accurate readings, the SWR meter itself must also match the line's impedance (typically 50 or 75 Ohms).
Pages in category "Lists of radio stations by frequency" The following 200 pages are in this category, out of approximately 338 total. This list may not reflect recent changes .
In the Americas (defined as International Telecommunication Union (ITU) region 2), the FM broadcast band consists of 101 channels, each 200 kHz wide, in the frequency range from 87.8 to 108.0 MHz, with "center frequencies" running from 87.9 MHz to 107.9 MHz. For most purposes an FM station is associated with its center frequency.
A transmatch (antenna tuner) is not required to use this antenna near its nominal design frequency of 14 MHz, and judicious length adjustments can sometimes include one other frequency band. All other frequencies require a transmatch. [citation needed] There are many variants of the G5RV antenna. Two variations of the G5RV design, called ZS6BKW ...
The 900 MHz frequency is also used as a reference band [2] e.g. to express the total power or impact of the electric field "E" - expressed in V/m - or the power density "S" - expressed in W/m 2 - of the overall cellular frequencies emission caused by all frequencies s.a. the four bands 850 / 900 / 1,800 / 1,900 MHz – which many GSM phones ...