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The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a shorted quarter-wave parallel transmission line stub. [5] [1] [6] For a transmitting antenna to operate efficiently, absorbing all the power provided by its feedline, the antenna must be impedance matched to the line; it must have a resistance equal to the feedline's characteristic impedance.
The most widely used types of feed line are coaxial cable, twin-lead, ladder line, and at microwave frequencies, waveguide. Particularly with a transmitting antenna, the feed line is a critical component that must be adjusted to work correctly with the antenna and transmitter. Each type of transmission line has a specific characteristic impedance.
Ladder line is an older, simpler form of parallel-wire line, often called open wire line. The configuration looks like a rope ladder , hence the name. It can either be purchased already made by a cable company, or home-made ; the construction is easy, though tedious, and originally all radio amateurs made their own open wire line.
An operator training simulator (OTS) is a computer-based training system that uses a dynamic simulation model of an industrial process, usually integrated with an emulator of the process plant's Distributed Control System (DCS). [1]
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Cattle grid on country road. Cattle grids are usually installed on roads where they cross a fenceline, often at a boundary between public and private lands. [5] They are an alternative to the erection of gates that would need to be opened and closed when a vehicle passes, and are common where roads cross open moorland, rangeland or common land maintained by grazing, but where segregation of ...
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The fence is usually 1.5–2 metres tall. The fencing can also incorporate specially made stiles and gates. The fence requires an abundance of wood, which was never a problem in Scandinavia, as the trees generally came from the owners' own forests in the process of thinning them out. The term ″roundpole fence" is somewhat misleading, as the ...