Just as important, special spot-beam antennas on the new spacecraft will be able to aim signals so precisely at many of the nation's largest cities that many more local television stations can be efficiently added to the satellite service.
12.
Some of the station's radio transmitters were utilized for wide area radio broadcasts using a single, constant radio frequency, while others provided dedicated radio transmissions, i . e . radio circuits, to individual Navy ships, using directional beam antennas.
13.
Power FM was operated from a tiny apartment in Castlebar for the summer of 1999 and broadcast to Mayo using a Veronica FM 250W stereo transmitter and a three element beam antenna giving the station over 900 Watts of power.
14.
These directional-antenna ( or " beam antenna " ) installations were known as the Imperial Beam system; Marconi Beam as a geographic place name still refers to a section of modern Cape Town, South Africa, as one location where such facilities historically had operated.
15.
The development of radar during World War II provided a great impetus to parabolic antenna research, and saw the evolution of shaped-beam antennas, in which the curve of the reflector is different in the vertical and horizontal directions, tailored to produce a beam with a particular shape.
16.
Also called a " beam antenna ", or " parasitic array ", the Yagi is very widely used as a high-gain antenna on the bandwidth of a Yagi antenna, the frequency range over which it has high gain, is narrow, a few percent of the center frequency, and decreases with increasing gain, so it is often used in fixed-frequency applications.
