Technical
This type of antenna is called a Hogg or horn-reflector antenna, invented by Alfred C. Beck and Harald T. Friis in 1941. It was built by D. C. Hogg. It consists of a flaring metal horn with a reflector mounted in its mouth, at a 45° angle. The reflector is a segment of a parabolic reflector, so the antenna is really a parabolic antenna fed off-axis. A Hogg horn combines several characteristics useful for radio astronomy: it is extremely broad-band, has calculable aperture efficiency, and the walls of the horn shield it from radiation coming from angles outside the main beam axis, so back and sidelobes are so minimal that scarcely any thermal energy is picked up from the ground. Consequently it is an ideal radio telescope for accurate measurements of low levels of weak background radiation. The antenna has a gain of about 43.3 dBi and a beamwidth of about 1.5° at 2.39 GHz. and an aperture efficiency of 76%.
Read more about this topic: Holmdel Horn Antenna
Famous quotes containing the word technical:
“I rather think the cinema will die. Look at the energy being exerted to revive it—yesterday it was color, today three dimensions. I don’t give it forty years more. Witness the decline of conversation. Only the Irish have remained incomparable conversationalists, maybe because technical progress has passed them by.”
—Orson Welles (1915–1984)
“In middle life, the human back is spoiling for a technical knockout and will use the flimsiest excuse, even a sneeze, to fall apart.”
—E.B. (Elwyn Brooks)
“The axioms of physics translate the laws of ethics. Thus, “the whole is greater than its part;” “reaction is equal to action;” “the smallest weight may be made to lift the greatest, the difference of weight being compensated by time;” and many the like propositions, which have an ethical as well as physical sense. These propositions have a much more extensive and universal sense when applied to human life, than when confined to technical use.”
—Ralph Waldo Emerson (1803–1882)