. Practical wireless telegraphy; a complete text book for students of radio communication . he passing wavewhen the wires are at right angles to the magnetic field and parallel to the static necessarily follows that if the loops of force radiated from the aerial of Fig. 99 do nothold their vertical position but are tilted forward, better distances would be covered, infact, more energy would be induced in the receiver aerial, if part of it were vertical andpart horizontal. 116. Directional Aerials.—It has been definitely proven by Marconi that ahorizontal aerial in which the length of
. Practical wireless telegraphy; a complete text book for students of radio communication . he passing wavewhen the wires are at right angles to the magnetic field and parallel to the static necessarily follows that if the loops of force radiated from the aerial of Fig. 99 do nothold their vertical position but are tilted forward, better distances would be covered, infact, more energy would be induced in the receiver aerial, if part of it were vertical andpart horizontal. 116. Directional Aerials.—It has been definitely proven by Marconi that ahorizontal aerial in which the length of the flat top largely exceeds the height will radiatemore strongly in the direction opposite to the free end. Also the strongest signals will peobtained at the receiver by an aerial, the free end of which points in the direction oppositeto the free end of the transmitting aerial. Taking full advantage of the unsymmetrical radiation from such aerials, the high powertransoceanic stations of the Marconi Company employ directional aerials exclusively. The 122 PRACTICAL WIRELESS AERIALS OR ANTENNAE. 123 flat tops of such aerials are from 3,000 to 6,000 feet in length, and from 300 to 450 inheight. The fundamental wave length is close to 10,000 meters. The greater part of the energy radiated from a transmitter may be confined to a givendirection by the use of the Bellini-Tosi aerial shown in Fig. 143. A triangular aerial,A, B, C, is supported by a vertical mast. The two sides of the triangle A, C, and B, an angle of 30° with the vertical, and the third side is horizontal to the earth withthe coil L-1 inserted at the center. L-1 is inductively coupled to a spark transmitter andtuned to syntony. An aerial of this type will radiate its energy with greatest intensity inthe direction of its own plane, the radiation in a direction perpendicular to the trianglebeing zero. In any direction making an angle 0 with the plane of the triangle, the intensityof the radiation v
Size: 1228px × 2034px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
