in England and America. Tesla sued Marconi's company for patent infringement but didn't have the resources to pursue the action. In 1943 the US Supreme Court invalidated the inductive coupling claims of Marconi's patent due to the prior patents of Lodge, Tesla, and Stone, but this came long after spark transmitters had become obsolete. The inductively coupled or "syntonic" spark transmitter was the first type that could communicate at intercontinental distances, and also the first that had sufficiently narrow bandwidth that interference between transmitters was reduced to a tolerable level. It became the dominant type used during the "spark" era. A drawback of the plain inductively coupled transmitter was that unless the primary and secondary coils were very loosely coupled it radiated on two frequencies. This was remedied by the quenched-spark and rotary gap transmitters (below). In recognition of their achievements in radio, Marconi and Braun shared the 1909 Nobel Prize in physics. First transatlantic radio transmission Marconi decided in 1900 to attempt transatlantic communication, which would allow him to compete with submarine telegraph cables. This would require a major scale-up in power, a risky gamble for his company. Up to that time his small induction coil transmitters had an input power of 100 - 200 watts, and the maximum range achieved was around 150 miles. To build the first high power transmitter, Marconi hired an expert in electric power engineering, Prof. John Ambrose Fleming of University College, London, who applied power engineering principles. Fleming designed a complicated inductively-coupled transmitter (see circuit) with two cascaded spark gaps (S1, S2) firing at different rates, and three resonant circuits, powered by a 25 kW alternator (D) turned by a combustion engine. The first spark gap and resonant circuit (S1, C1, T2) generated the high voltage to charge the capacitor (C2) powering the second spark gap and resonant circuit (S2, C2, T3), which generated the output. The spark rate was low, perhaps as low as 2 - 3 sparks per second. Fleming estimated the radiated power was around 10 - 12 kW. The transmitter was built in secrecy on the coast at Poldhu, Cornwall, UK. Marconi was pressed for time because Nikola Tesla was building his own transatlantic radiotelegraphy transmitter on Long Island, New York, in a bid to be first (this was the Wardenclyffe Tower, which lost funding and was abandoned unfinished after Marconi's success). Marconi's original round 400-wire transmitting antenna collapsed