Wireless Telegraphy - History of Development - Period 1838-1897 - Marconi


By 1897, Guglielmo Marconi conducted a series of demonstrations with a radio system for signalling for communications over long distances. Marconi is said to have read, while on vacation in 1894, about the experiments that Hertz did in the 1880s. Marconi also read about Tesla's work. It was at this time that Marconi began to understand that radio waves could be used for wireless communications. Marconi's early apparatus was a development of Hertz’s laboratory apparatus into a system designed for communications purposes. At first, Marconi used a transmitter to ring a bell in a receiver in his attic laboratory. He then moved his experiments out-of-doors on the family estate near Bologna, Italy, to communicate farther. He replaced Hertz’s vertical dipole with a vertical wire topped by a metal sheet, with an opposing terminal connected to the ground. On the receiver side, Marconi replaced the spark gap with a metal powder coherer, a detector developed by Edouard Branly and other experimenters. Marconi transmitted radio signals for about a mile at the end of 1895.

By 1896, Marconi introduced to the public a device in London, asserting it was his invention. Despite Marconi's statements to the contrary, though, the apparatus resembles Tesla's descriptions in his research, demonstrations and patents. Marconi's later practical four-tuned system was pre-dated by N. Tesla, Oliver Lodge, and J. S. Stone. He filed a patent on his earliest system with the British Patent Office on June 2, 1896.

In 1897, Marconi was awarded a patent for radio with British patent No. 12,039, Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for. The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters (primarily Tesla) and resembled the instrument demonstrated by others (including Popov). During this time, spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, Preece delivered his lecture, "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution in London, stating that Marconi had invented a new relay which had high sensitivity and delicacy.

In 1896, Jagdish Chandra Bose went to London on a lecture tour and met Marconi, who was conducting wireless experiments for the British post office. In 1897, Marconi founded the Marconi Company Ltd.. Also in 1897, Marconi established the radio station at Niton, Isle of Wight, England. Marconi's wireless telegraphy was inspected by the Post Office telegraph authorities; they made a series of experiments with Marconi's system in the Bristol Channel. In October 1897, wireless signals were sent from Salisbury Plain to Bath, a distance of 34 miles. Marconi's reputation is largely based on the formulation of Marconi's law (1897), and other accomplishments in radio communications and commercializing a practical system.

Post Office Engineers inspect Marconi's equipment on Flat Holm, May 1897

Other experimental stations were established at Lavernock Point, near Penarth; on Flat Holm, off Cardiff in the Bristol Channel, and at Brean Down, a promontory on the Somerset side. Signals were obtained between the first and last-named points, a distance of approximately eight miles. The receiving instrument used was a Morse inkwriter of the Post Office pattern.

Read more about this topic:  Wireless Telegraphy, History of Development, Period 1838-1897