Radio Broadcast (May-Oct 1922)

Developments in High-Power Radio And Its Practical Application in the Services of the United States Navy By COMMANDER STANFORD C. HOOPER, U. S. N. Head of the Radio Division in the Bureau of Engineering, Navy Department PART II THE passage by Congress of the Naval Appropriation Act of August 22, 1912, contributed greatly to the advancement of the radio art as regards the development of high-power radio, not only in the United States but throughout the world. It gave to the Naval radio service a great opportunity, but it also placed a heavy responsibility on those entrusted with the direction and administration of the service. This Act appropriated $1,500,000 for the establishment of six of the Navy's projected high-power stations, those to be located in the Isthmian Canal Zone, on the California Coast, in the Hawiian Islands, in American Samoa, at Guam and in the Philippines. This constituted a programme of great magnitude in high-power radio construction and one which obviously was difficult of accomplishment at that period. The trail had not yet been blazed in this direction and little information of a practical nature was available. The Arlington station was under construction but had not yet been finished; so that definite information was not available as to what could be expected from a station of this type. The plans for the six new stations therefore must necessarily be held in abeyance pending the completion and testing of the pioneer highpower Arlington station. Being a pioneer in substantial high-power radio construction, this station must be regarded in the light of an experiment. Because of insufficient scientific knowledge at that time, mistakes were made in the establishment of the Arlington station, principal among which were locating the station on high ground and placing the steel towers too close together, but nevertheless this station has rendered most valuable service to the Government ever since it was placed in commission, and moreover it served as a guide by which similar mistakes on a larger scale were avoided. It also made available a high-power station for testing difl'erent types and makes of apparatus in actual service, thereby enabling the selection of the most efficient type of equipment available for service at that time, it was, in short, the agency by which delay was avoided in establishing the extensive radio system required to meet the needs of our Atlantic, Pacific, and Asiatic Fleets and other government agencies. The Arlington station may justly be regarded as the pioneer development in high-power radio in the world, as well as the fountain head of the Navy 's existing radio service, a service of which the stations on shore extend more than one quarter the distance around the world and whose signals are constantly encompassing the globe. The true significance of the Arlington station will not be fully appreciated until the history of radio is finally written. THE POULSEN ARC TRANSMITTER UNDOUBTEDLY the second feature of importance in connection with the development of radio in the United States, especially as regards high power, is the Poulsen-Federal arc converter. This type of transmitter, successfully developed by the ingenuity of American radio engineers from powers of 30 KW to 1 ,000 KW within a brief interval of ten years, and manufactured in the United States, is the outstanding unit of apparatus in the Naval radio service. Arc transmitters have given satisfaction in the services where they have been employed for powers from 2 KW to 1,000 KW. The Navy has used this type of apparatus in its high-power stations continuously since the first 30-KW arc transmitter was tested out in the Arlington station ten years ago. Arc transmitters produce harmonics as do other types of transmitters. They also produce a form of interference called "mush," the cause of which is not yet thoroughly understood. Two waves were also radiated, instead of one, in the sy stem of signaling