Search results
Results from the WOW.Com Content Network
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.
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.
Because the troposphere is turbulent and has a high proportion of moisture, the tropospheric scatter radio signals are refracted and consequently only a tiny proportion of the transmitted radio energy is collected by the receiving antennas. Frequencies of transmission around 2 GHz are best suited for tropospheric scatter systems as at this ...
An antenna tuner, a matchbox, transmatch, antenna tuning unit (ATU), antenna coupler, or feedline coupler is a device connected between a radio transmitter or receiver and its antenna to improve power transfer between them by matching the impedance of the radio to the antenna's feedline. Antenna tuners are particularly important for use with ...
An antenna rotator (or antenna rotor) is a device used to change the orientation, within the horizontal plane, of a directional antenna. Most antenna rotators have two parts, the rotator unit and the controller. The controller is normally placed near the equipment which the antenna is connected to, while the rotator is mounted on the antenna ...
The commercially available B&W AC3-30 and B&W DS1.8-30 antennas [6] vary from the above to cover 3–30 MHz using a 90 foot length with an 18 inch spacing of the wires. The balun is a 16:1 ratio, thereby transforming the 50 Ω (ohm) coax to an 800 Ω feed at the antenna.