Page:Popular Science Monthly Volume 89.djvu/644

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��Popular Science Mcndhly

��Employing Kites to Support an Aerial

��A DOZEN yciirs ago there occurred to Army officers the idea of sending up a wireless aerial to a great height by means of kites, in order to increase the sending and receiving range of a field radio set. A few experiments were made, but without great success. In 1908 further attempts were made in this line, but again without especially en- couraging results.

After the German steamship, Prinz Eitel I-Viedrich, had been interned at Norfolk, Va., last spring, a story leaked out as to how her captain (Herr Thierich-

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���Manner of keeping aloft aerials with a string of kites on a line of unvarying length

sen) kept posted as to the wiiereabouts of enemy ships, and was thus able to avoid them for many months. lie adopted the simi)le expedient of sentling aloft an aerial sup[)orted by a string of kites. Such excellent results were ob- tained that a paper containing wireless news of the war was prinli'd daily on board shi.

i<e( ailing this use of kiti's by thetier- man ship, ,\djulanl (ieneral Cole, of the Massachusetts V'olunli'ir Militia, decided to resume ex|)eriments with a kite-supported aerial. C'onsc(|uently lie in\'ilcd Sainne!!•". I'erkins, of Hoston,

��make some further tests at the July maneuvers of the Militia in northeastern Massachusetts. Late one afternoon, at Newbury, Mr. Perkins sent up four of his huge hexagon kites. The aerial was attached to the kite line about half way between the kites and the earth, and hung vertically a distance of about 600 ft. to the ground. The lower end Avas attached to an ordinary >:»-k. w. field radio set, such as is used ordinarily with a 25 or 30-ft aerial. The swaying up and down of the kites caused the end of the aerial to be jerked off the earth or to coil up upon it, and consequently the operator was unable to tunc, because of the constantly varying length of the aerial. He explained to Mr. Perkins that this was the cause of failure in many earlier kite experiments. With Yankee ingenuity Mr. Perkins soon put an end to the varying in length of the wire, and from that moment almost startling results were obtained.

The method by which the aerial was kept at an unvarying length is illustrated in the diagram, where ,4, B and C represent the kite line in three different positions corresponding to the verticals D, D\, and D2. A shows the lowest and C the highest positions of the constantly swaying kites. By securing the vertical aerial wire to the ground when the kite line has reached its lowest angle, any fuither rise of the line occurs from the point D at the toj) of the aerial instead of from the point where the kite line is secured to the ground. Consequently, the point D always remains at a given height and the length of the aerial is always the same. It was this simple idea of holding down the kite line by means of tile aerial itself that made the ditfer- ence between success and failure, and made it possible to increase the range of an ordinary ,'4-k. w. wireless set so greatly that it became in many ways the etiual of a big tractor-.sct worth thousands of dollars.

As soon as the aerial was kepi at an uinarying length in (he experiment men- tioned above, messages were received from the I'ilene Station at Boston, from the Battleshi)) Georgia olT Newport, from .Arlington, Va., and even from as far away as Bermuda, a distance of over a thous.ind miles.

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