Mackay Radio Telegraph Co v. Radio Corporation of America 14 8212 15, 1938

• Decision Date: 30 January 1939
• Docket Number: No. 127,127
• Citation: 40 USPQ 199,306 U.S. 86,83 L.Ed. 506,306 U.S. 618,59 S.Ct. 427
• Parties: MACKAY RADIO & TELEGRAPH CO., Inc., v. RADIO CORPORATION OF AMERICA. Argued Dec. 14—15, 1938
• Court: U.S. Supreme Court

306 U.S. 86

59 S.Ct. 427

306 U.S. 618

83 L.Ed. 506

MACKAY RADIO & TELEGRAPH CO., Inc.,

v RADIO CORPORATION OF AMERICA.

No. 127.

Argued Dec. 14—15, 1938.

Decided Jan. 30, 1939.

As Modified on Denial of Rehearing March 6, 1939.

Mr. Samuel E. Darby, Jr., of New York City, for petitioner.

Mr. Jo. Baily Brown, of Pittsburgh, Pa., for respondent.

[Argument of Counsel from page 87 intentionally omitted] Mr. Justice STONE delivered the opinion of the Court.

The questions presented for decision by the petition for certiorari are whether the Carter patent, No. 1,974,387, of September 18, 1934, for a directive antenna system for use in radio communication, is valid and is infringed by antennae structures used by petitioner in such communication.

Respondent brought the present suit in the District Court for eastern New York to enjoin infringements of four patents relating to radio antennae or their operation. Two were those of Carter and two those of Lindenblad. Of these only the second Lindenblad patent, No. 1,927,522, of September 19, 1933, for an antenna for radio communication, is of present importance. When the suit was begun the application for the third Carter patent, with which we are presently concerned, was pending. After petitioner had answered and respondent, as a result of the litigation, had acquired knowledge of the particulars of the structure and operation of petitioner's antennae, Carter, respondent's assignor, amended the statement of his invention in his application so as in terms to embrace a differentiating feature of petitioner's structures. After this patent was issued respondent was permitted to file a supplemental bill charging infringement of it. The suits were consolidated, and the parties proceeded to trial on the issues of the validity and infringement of all five patents.

After taking the voluminous testimony of numerous witnesses, the trial court found that none of the patents in suit was infringed and decreed that the suits be dismissed. D.C., 16 F.Supp. 610. It held that none of them was a pioneer patent; that none had been employed by any one; that respondent's commercial structures did not follow the teachings of any of them; and that consequently they were not entitled to a broad construction. With respect to the Carter patent in suit it said (page 621): 'The disclosure and the claims were broadened, not only contrary to their original terminology, but to their spirit as well.' And '* * * by those amendments the plaintiff attempted to mold the third Carter patent both as to disclosure and claims, to cover defendant's antenna systems. This could not lawfully be done.'

On appeal from so much of the decree as related to the second Lindenblad patent and the third Carter patent, the Court of Appeals for the Second Circuit affirmed as to the Lindenblad patent, but reversed as to the Carter patent, holding Claims 15 and 16 valid and infringed. 96 F.2d 587. We granted certiorari, 305 U.S. 582, 59 S.Ct. 73, 83 L.Ed. —-, because of the nature and importance of the case, on a petition which urged as grounds for its allowance that validity and infringement of the Carter patent were in doubt and that, as petitioner is the only competitor of respondent in the business of world wide public radio communication, further litigation, resulting in conflict of decision among circuits, was improbable.

In ordinary broadcasting, radio waves are projected in all directions from the sending station. In radio communication it is advantageous and has long been the practice to use a directive antenna by which the waves of radio activity emanating from it are projected as a beam in the direction of the receiving station. In practice the beam is directed at an angle from the earth's surface toward the ionized layer of the stratosphere, or Heaviside layer, from which the beam is deflected toward the earth's surface in the compass direction of the receiving station. In more recent years it has been the practice to use relatively short wave lengths for radio communication.

The radio waves are generated at the sending station by feeding an oscillating electric current of appropriate character into the wire or wires of the antenna. The electric waves in the wires energize radio activity, which the antenna projects as radio waves toward the receiving station. By modulating or interrupting the current, corresponding modulation or interruption of the radio waves is effected, which may be used as a means of transmitting any desired signal. The waves, as modulated, impinge on the antenna of the receiving station devised to receive and utilize them as a means of controlling, with corresponding modulation, an electric current which in turn actuates a mechanism contrived to give audible or visual expression to the transmitted signal.

The effective part of the antenna is a copper wire from which the radio waves are radiated, supported on towers or poles at a height above the ground depending on the wave length used. The wire may be parallel with the earth, or vertical, or arranged at an angle, depending upon the function to be performed. Before Carter, antennae of two or more wires in varying arrangement had been used. The second Lindenblad patent showed an antenna of two wires arranged at an angle in the form of a V or an X, and it pointed out that in such an arrangement radiation will take place in the direction of the axis or bisector of the angle of the diverging wires, and that 'the spacing at the open end (of the wires), while variable over a great range, should be in the neighborhood of a fifth of the length, and the length of each antenna section should be of the order of magnitude of five to ten waves long.'

While such an arrangement projects the radio waves principally in two directions along the bisector of the angle of the antenna wires, the prior art had made use of an arrangement of wires, parallel to the wires of the angu- lar antenna, as a 'reflector' by which the radiation was projected as a beam in one direction away from the reflector and along the bisector of the angle of the wires.

The present Carter patent is for an 'antenna system utilizing standing wave phenomena.' Like the second Lindenblad patent, it is concerned with a V antenna by which the principal radiation is directed in the plane of the wires along the bisector of their angle. The disclosure of the patent, in which the court below found invention, was that the best directional radio propagation by the V type antenna is obtained with a structure in which the angle of the wires, their length, and the length of wave propagated are in a definite mathematical relationship expressed by a formula disclosed in the specifications.

In explaining his invention, Carter pointed out that 'It is known that when a wire having a length greater than the operating wave length is excited in such manner that standing waves are produced thereon, radiation will occur principally in the direction of symmetrical cones having their apices at the center of the wire. Such is the case with a wire having a length equal to a plurality of one-half wave lengths at the operating frequency. The radiation pattern produced in such instance appears, in cross section, in the form of symmetrical cones about the wire. The present invention which makes use of these phenomena, in its most simple aspect employs a pair of open-ended wires energized in phase opposition to have standing waves throughout the length of the wires, the wires having such angular relation with respect to each other as to obtain a highly directional, efficient and simple antenna system.¹

The patent states the mathematical formula by which the desired relationship is secured, which shows that the appropriate angle between each of the antenna wires and their bisector depends upon the wave length to be propagated and the use of antenna wires of a length which is a multiple of half wave lengths.²

The significance of the formula lies in the fact that the angle between the wire and the direction of greatest radio activity is a trigonometrical function of two variables, the wave length used and the 'number of half wave lengths contained in the wire', and that, as the application stated, the use of the formula in practice presupposes the use of a wire whose length is a multiple of half wave lengths. The patent then explains that the angle of the formula is the angle between each wire of the V antenna and its bisector—in other words, that the angle of the wires of the antenna is twice and hence, like the angle of the formula, is a function of the wave length and the length of the wires, which are each a multiple of half wave lengths long.

Carter did not invent the formula. It had been developed by Abraham and published in a scientific journal thirty years before. Annalen der Physik, 1898, Physikalische Zeitschrift, March 2, 1901. Abraham's formula expressed the scientific truth that when radio activity is projected from a charged wire of finite length, i.e., one having standing waves, and having a length of a multiple of half wave lengths, the angle between the direction of the principal radio activity and the wire is dependent on wave length and wire length, which is a multiple of half wave lengths. Lindenblad had described his antenna as using either standing or traveling waves and, as we have seen, had taught that with an arrangement of antenna wires at an angle, radiation will occur substantially in the direction of the bisector of the angle and that the preferred angle was dependent upon an indicated relationship between wire length and wave length.

It is plain, therefore, that the Carter invention, if it was invention, consisted in taking the angle of the Abraham formula as the angle between each wire of the V antenna and its bisector. By so doing he brought the cones of principal radio activity, each having one of the wires of the antenna as its axis, into conjunction at their periphery and...