Radio age (Jan 1927-Jan 1928)

16 RADIO AGE for January, 1927 meters. Observations of direction at this time all showed that the monument was the source, thus indicating it was set in oscillation at the third harmonic of the Arlington wave and was thus radiating into the surrounding region." This disclosure would seem to imply that the memory of George Washington may, in the future, be held accountable for some of the ills which beset radio reception. Broadcast listeners who complain to Secretary of Commerce Herbert Hoover about radiating regenerative sets, interference from the Annapolis arc station and code from the Arlington naval station, may protest against a radiating Washington monument! Those that would besmirch the name of the Father of Our Country by referring to his beer recipe and his fondness for the feminine gender may contend that radio interference from the Washington monument is a haunting memory or proof of the adage that "the evil that men do lives after them!" Jesting aside, the scientific investigation into the influence of this shaft in distorting radio waves produced interesting and valuable information. Natural Wavelength TESTS in proximity to the Washington monument indicated that the greatest distortion of the wave front was at 625 meters, which observation led to the conclusion that this is the natural wave length of the marble shaft. Signals were sent from a specially installed transmitting station, located at the Soldiers' Home, on a series of wave lengths, ranging from 400 to 1,000 meters. The directionfinder was stationed, successively, at each of six positions at increasing distances from the monument. Observations were made of the horizontal angle through which the directionfinder must be turned in order to obtain a minimum signal. Some of the observations were productive of peculiar twists of the radio waves; this phenomenon leading the investigators to conclude that these strange distortions were traceable to an underground cable line extending in a southeasterly direction. With a portable directionfinding outfit, the representatives of the Bureau of Standards invaded a valley, through which coursed a brook, 25 feet wide. Alfred Tennyson, in writing his poem, "The Brook," was not equipped with such modern instruments, and neither were these fact-searching scientists provided with a poetic license. They are content in informing a radio-interested world that a small body of water causes little distortion to radio waves. The direction-finder was carried from point to point along this Jeisurely-moving brook, and only in one instance did the invisible wave swerve to any appreciable degree. At this particular point a tree, only six feet away, was held responsible for the radio wave wandering from its path of rectitude. The tentative conclusion that trees cause deviation of wave fronts prompted the Bureau of Standards to focus its direction finder around a tree in an open field. While the transmitting set, located a number of miles away, at the Soldiers' Home, was sending on wave lengths of 400 and 1,400 meters, respectively, there was a negligible amount of distortion, either directly in front or behind the tree. However, when the coil antenna and receiving set were placed to the right or left of the tree the intercepted radio wave deviated as much as five degrees. The tree involved in this test was only 40 feet high ; which factor prompts the Government investigators to assume that greater distortion would be caused by proportionately larger trees. Radio experimenters might pursue ffhis line of investigation with interesting results. If broadcast listeners reside in the vicinity of a water tower, this form of structure may prove to be the source of radiation of radio waves — a sort of secondary broadcasting station, if you please! Distortion tests were conducted in proximity to The Magazine of the Hour a 150-foot water tower and an electric-power line nearby. The waves swerved considerably but, we are told, that "Observations on the longer wavelength — 1,400 meters — indicated that a large part of the distortion may be due to the power wires near which the observations were taken. On the shorter waves the distortion is in such a direction that radiation from the tower is indicated, though the observations on 625 meters make it uncertain whether this is the entire cause!" Banks and shore lines of rivers may be disconcerting to the otherwise unimpeded progress of all-embracing radio waves. Thus, if you are camping and fishing this coming Summer, with a radio receiving set and loop as a pick-up system, the waves from your favorite broadcasting station may be slightly distorted and your coil antenna, in effect, may lose some of its otherwise sharp directional properties. However, tests behind a 20-foot bank afforded proof of relatively little deviation of radio waves. Furthermore, we are informed that a wave speeding over one-half mile of fresh water, approaching the shore line at an angle of 500 degrees, is not distorted appreciably. A concrete bridge, if it contains iron reinforcements, is apt to bend radio waves considerably— that is, cause a relatively wide deviation. The Radio Laboratory of the Bureau of Standards placed its portable radio direction — finding equipment on a 150-foot reinforced concrete bridge. Curves plotted as a result of this test showed large angles of distortion, which are attributed to the iron reinforcements of the bridge. In another test, in a small valley — a cut of 500 feet long and 50 feet deep — which was spanned by a small frame bridge, the direction-finder failed to disclose any appreciable distorting affect of the speeding invisible waves. A telephone line crossed this valley, parallel to the bridge. Distortion measurements were