U.S. Supreme Court
MARCONI WIRELESS T. CO. OF AMERICA v. U.S., 320 U.S. 1 (1943)
320 U.S. 1
MARCONI WIRELESS TELEGRAPH CO. OF AMERICA
v.
UNITED STATES.
The Tesla patent No. 645,576, applied for September 2, 1897 and allowed March 20, 1900, disclosed a four-circuit syst m, having two circuits each at transmitter and receiver, and recommended that all four circuits be tuned to the same frequency. Tesla's apparatus was devised primarily for the transmission of energy to any form of energy-consuming device by using the rarified atmosphere at high elevations as a conductor when subjected to the electrical pressure of a very high voltage. But he also recognized that his apparatus could, without change, be used for wireless communication, which is dependent upon the transmission of electrical energy. His specifications declare: 'The apparatus which I have shown will obviously have many other valuable uses-as, for instance, when it is desired to transmit intelligible messages to great distances ...' 11
Tesla's specifications disclosed an arrangement of four circuits, an open antenna circuit coupled, through a transformer, to a closed charging circuit at the transmitter, and an open antenna circuit at the receiver similarly coupled to a closed detector circuit. His patent also in- [320 U.S. 1, 15] structed those skilled in the art that the open and closed circuits in the transmitting system and in the receiving system should be in electrical resonance with each other. His specifications state that the 'primary and secondary circuits in the transmitting apparatus' are 'carefully synchronized.' They describe the method of achieving this by adjusting the length of wire in the secondary winding of the oscillation transformer in the transmitter, and similarly in the receiver, so that 'the points of highest potential are made to coincide with the elevated terminals' of the antenna, i.e., so that the antenna circuit will be resonant to the frequency developed in the charging circuit of the transmitter. The specifications further state that 'the results were particularly satisfactory when the primary coil or system A with its secondary C (of the receiver) was carefully adjusted so as to vibrate in synchronism with the transmitting coil or system AC.'
Tesla thus anticipated the following features of the Marconi patent: A charging circuit in the transmitter for causing oscillations of the desired frequency, coupled, through a transformer, with the open antenna circuit, and the synchronization of the two circuits by the proper disposition of the inductance in either the closed or the antenna circuit or both. By this and the added disclosure of the two-circuit arrangement in the receiver with similar adjustment, he anticipated the four circuit tuned [320 U.S. 1, 16] combination of Marconi. A feature of the Marconi combination not shown by Tesla was the use of a variable inductance as a means of adjusting the tuning the antenna circuit of transmitter and receiver. This was developed by Lodge after Tesla's patent but before the Marconi patent in suit.
MARCONI WIRELESS T. CO. OF AMERICA v. U.S., 320 U.S. 1 (1943)
320 U.S. 1
MARCONI WIRELESS TELEGRAPH CO. OF AMERICA
v.
UNITED STATES.
The Tesla patent No. 645,576, applied for September 2, 1897 and allowed March 20, 1900, disclosed a four-circuit syst m, having two circuits each at transmitter and receiver, and recommended that all four circuits be tuned to the same frequency. Tesla's apparatus was devised primarily for the transmission of energy to any form of energy-consuming device by using the rarified atmosphere at high elevations as a conductor when subjected to the electrical pressure of a very high voltage. But he also recognized that his apparatus could, without change, be used for wireless communication, which is dependent upon the transmission of electrical energy. His specifications declare: 'The apparatus which I have shown will obviously have many other valuable uses-as, for instance, when it is desired to transmit intelligible messages to great distances ...' 11
Tesla's specifications disclosed an arrangement of four circuits, an open antenna circuit coupled, through a transformer, to a closed charging circuit at the transmitter, and an open antenna circuit at the receiver similarly coupled to a closed detector circuit. His patent also in- [320 U.S. 1, 15] structed those skilled in the art that the open and closed circuits in the transmitting system and in the receiving system should be in electrical resonance with each other. His specifications state that the 'primary and secondary circuits in the transmitting apparatus' are 'carefully synchronized.' They describe the method of achieving this by adjusting the length of wire in the secondary winding of the oscillation transformer in the transmitter, and similarly in the receiver, so that 'the points of highest potential are made to coincide with the elevated terminals' of the antenna, i.e., so that the antenna circuit will be resonant to the frequency developed in the charging circuit of the transmitter. The specifications further state that 'the results were particularly satisfactory when the primary coil or system A with its secondary C (of the receiver) was carefully adjusted so as to vibrate in synchronism with the transmitting coil or system AC.'
Tesla thus anticipated the following features of the Marconi patent: A charging circuit in the transmitter for causing oscillations of the desired frequency, coupled, through a transformer, with the open antenna circuit, and the synchronization of the two circuits by the proper disposition of the inductance in either the closed or the antenna circuit or both. By this and the added disclosure of the two-circuit arrangement in the receiver with similar adjustment, he anticipated the four circuit tuned [320 U.S. 1, 16] combination of Marconi. A feature of the Marconi combination not shown by Tesla was the use of a variable inductance as a means of adjusting the tuning the antenna circuit of transmitter and receiver. This was developed by Lodge after Tesla's patent but before the Marconi patent in suit.