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Transmit diversity is the use of multiple transmit antennas to achieve reliability in radio communication. [1] It involves using signals that originate from two or more independent sources that have been modulated with identical information-bearing signals and that may vary in their transmission characteristics at any given instant.
The AT&T receiving Beverage antenna (left) and radio receiver (right) at Houlton, Maine, used for transatlantic telephone calls, from a 1920s magazine. The Beverage antenna or "wave antenna" is a long-wire receiving antenna mainly used in the low frequency and medium frequency radio bands, invented by Harold H. Beverage in 1921. [1]
This is because wavelength is inversely proportional to frequency (wavelength in metres = 299,792,458 / frequency in Hz), and transmitter efficiency is severely degraded if the length of the antenna is shorter than 1/4 wavelength. They used grounded or insulated guyed masts with umbrella antennas, or wire-spans across both valleys and fjords.
A manual transmission (MT), also known as manual gearbox, standard transmission (in Canada, the United Kingdom and the United States), or stick shift (in the United States), is a multi-speed motor vehicle transmission system where gear changes require the driver to manually select the gears by operating a gear stick and clutch (which is usually ...
The antenna and transmission line no longer have the same impedance, and the signal will be reflected back into the antenna, reducing output. This could be addressed by changing the matching system between the antenna and transmission line, but that solution only works well at the new design frequency.
The antenna feed system or antenna feed is the cable or conductor, and other associated equipment, which connects the transmitter or receiver with the antenna and makes the two devices compatible. [ 1 ] [ 2 ] In a radio transmitter, the transmitter generates an alternating current of radio frequency , and the feed system feeds the current to ...
The transmission signal of the up-link, of relatively high power (1, 2, or 5 watts for common VSAT equipment) originating from BUC and the very low power received signal power (in the order of μV) coming from the antenna to the LNB receiver unit, in this case are at an angle of 90° relative to each other, are both coupled together at the feed ...
A double antenna tuning inductor house near the summit of Cefn Du and to the rear of the 1914 antenna, served to tune the antenna and earth screens of what were now two parts of a whole antenna, fed at the western transmitter building. The extension also had inductors at the far end, such that each part of the antenna had inductors at its ends.