Search results
Results from the WOW.Com Content Network
Square keys are used for smaller shafts and rectangular faced keys are used for shaft diameters over 6.5 in (170 mm) or when the wall thickness of the mating hub is an issue. Set screws often accompany parallel keys to lock the mating parts into place. [3] The keyway is a longitudinal slot in both the shaft and mating part.
A helical antenna is an antenna consisting of one or more conducting wires wound in the form of a helix. A helical antenna made of one helical wire, the most common type, is called monofilar , while antennas with two or four wires in a helix are called bifilar , or quadrifilar , respectively.
The system consists of a master antenna and a matching transformer to match the balanced antenna with unbalanced cable and amplifiers. [5] Most antennas have an impedance of around 300 Ω. To convert it to 75 Ω, a matching transformer (or balun ) is used.
Sellers often claim to supply a special digital or high-definition television (HDTV) antenna advised as a replacement for an existing analog television antenna; at best this is misinformation to generate sales of unneeded equipment, [9] [10] At worst, it may leave the viewer with a UHF-only antenna in a local market (particularly in North ...
Antenna directivity is the ratio of maximum radiation intensity (power per unit surface) radiated by the antenna in the maximum direction divided by the intensity radiated by a hypothetical isotropic antenna radiating the same total power as that antenna. For example, a hypothetical antenna which had a radiated pattern of a hemisphere (1/2 ...
A small loop antenna, on the other hand, has lower radiation resistance [b] and is not self-resonant; it requires some form of impedance matching to counter the loop's reactance – in practice, this usually consists of a variable capacitor bridging the point corresponding to the gap of a halo. Connection diagram for a gamma matched halo antenna.
Get answers to your AOL Mail, login, Desktop Gold, AOL app, password and subscription questions. Find the support options to contact customer care by email, chat, or phone number.
Slotted array UHF television broadcasting antenna. As shown by H. G. Booker in 1946, from Babinet's principle in optics a slot in a metal plate or waveguide has the same radiation pattern as a driven rod antenna whose rod is the same shape as the slot, with the exception that the electric field and magnetic field directions are interchanged; the antenna is a magnetic dipole instead of an ...