Radio Broadcast (May-Oct 1922)

76 RADIO BROADCAST Candler thereupon offered to transmit a general message bearing the girl's description and asking for information regarding her whereabouts. The first radiogram of this nature was sent late in January and was, of course, picked up and relayed by hundreds of other amateurs throughout the country who were only too willing to help in the search. Archer, meanwhile, sat night after night at his receiving set listening for a possible encouraging reply. Weeks passed and it began to look like a hopeless task when one evening, the faint call "8KV" (Archer's registered call signal) came from another amateur located at Van Wert, Ohio. Following this call, came some words hardly discernible, so faint were they, and in which young Archer was able to distinguish the words "your sister." Late at night of the same day, when most amateurs had closed for the night and local interference had subsided, Archer was again able to establish communication with the Van Wert station and was informed that a young girl answering the radioed description of his sister was living at the home of a near-by farmer at Rockford, Mercer County, Ohio. Moreover, this amateur flashed back that he had been trying to reach Archer for the past two weeks but without success, owing to the limited range of his sending equipment. Needless to add, it did not take long for Archer and his mother to investigate the radioed report. Much to their surprise and joy, the report proved correct and the girl was recognized instantly as the long lost one. The story of Archer and his unique use of the ether is indeed an achievement to amateur radio of this country. To-day, with our great and far reaching radio telephone broadcasting stations throughout the country, we have at our disposal, probably, the most effective and inexpensive means of locating absent ones yet devised, and as the fame and worth of radio spreads far and wide it is quite reasonable to expect police officials to resort to its use for a multitude of purposes, whether for seeking the whereabouts of lost ones or for hunting criminals. In the next number of the magazine this department will tell some adventures of radio in the police departments of our large cities, describing some actual instances which have occurred up to date and probable ones oj the future. * THE GRID Questions and Answers The Grid is a Question and Answer Department maintained especially jor the radio amateurs. Full answers will be given wherever possible. In answering questions those of a like nature will be grouped together and answered by one article. Every effort will be made to keep the answers simple and direct, yet fully self-explanatory. Questions should he addressed to Editor, " The Grid," Radio Broadcast, Garden City, N. Y. The letter containing the questions should have the full name and address of the writer and also his station call letter, if he has one. The questions and answers appearing in this issue are chosen from among many asked the editor in other capacities. What is a loop antenna? Will a coil antenna work if it is inside a house? How does a radio compass work? How many turns should he in a loop antenna to receive from a broadcasting station on }6o meters? Loop or Coil Antenna THE names loop antenna and coil antenna are used to designate the same kind of an antenna. This antenna is mainly used in the reception of radio waves. It consists of a boxlike frame upon. which is wound turns of wire. The frames may be of different sizes, but the usual sizes are 4, 6, or 8 feet square. They should be made so that they can be rotated around an axis, such as X-X^ in figures 1 , 2 and 3. (See page 78) . Figures i and 2 show two different ways of winding the wire on the frame. In Figure i the wire has been wound on the outside of the frame. In Figure 2, the wire has been wound on the frame. Thus the wire lies in the same vertical plane. The distance between the turns of wire is called the spacing. This is represented at a in Figure I . Figure 3 shows a good method of constructing the frame work for a loop antenna. The diagonal pieces aa^ and bh^ should be made wide enough at the ends to permit the proper spacing