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U.S. Supreme Court

Mackay Radio & Telegraph Co. v. Radio Corp. of America, 306 U.S. 86 (1939)

Mackay Radio & Telegraph Co. v. Radio Corporation of America

No. 127

Argued December 14, 15, 1938

Decided January 30, 1939

306 U.S. 86


1. Carter patent, No. 1,974,387, for a directive antenna system for use in radio communication, held not infringed by petitioner's antenna structures. Pp. 306 U. S. 88, 306 U. S. 101.

Claims 15 and 16 are invalid so far as they claim antennae of wire lengths intermediate of multiples of half-wavelengths. And, so far as the patent discloses and claims invention of a V antenna structure made in conformity to the Abraham formula, petitioner's structures do not infringe, for none of them conforms to the Abraham formula. One has wires which are an integral number of half-wavelengths long, but uses an angle 10% smaller than that derivable from the Abraham formula; all of the others have wires which are not multiples of half-wavelengths long and angles not derivable from the formula.

2. The disclosure of the Carter patent was that the best directional radio propagation by the V type antenna is obtained in the direction of its bisector, 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. The formula shows that the appropriate angle between each of the antenna wires and their bisector depends upon the wavelength to be propagated and the wire length, which is a multiple of half-wavelengths. The formula had been developed and published by Abraham thirty years previously. Lindenblad had taught that, with an arrangement of antenna wires at an angle, radiation will occur in the direction of the bisector of the angle, and that the preferred angle was dependent upon an indicated relationship between wire length and wavelength. Carter's invention therefore, 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, and thus establishing along the bisector the greatest directional radio activity. The empirical formula of the specifications and Claims 15 and chanrobles.com-red

Page 306 U. S. 87

16, derived graphically from the Abraham formula, disclosed no invention other than the application of the Abraham formula to the V antenna when wavelength and wire length are known.

Held, assuming that it was more than the skill of the art to combine the teaching of Abraham with that of Lindenblad and others who had pointed out that the arrangement of the wires at an angle enhanced directional radio activity along their bisector, then the invention was a narrow one, consisting of a structure conforming to the teachings of the Abraham formula as to angle and wire length relative to wavelength, and is to be strictly construed with regard both to prior art and to alleged infringing devices. Carter, avoiding prior art by defining his angle for antennae with wires of particular wavelengths with mathematical precision, cannot discard that precision to establish infringement. Pp. 306 U. S. 94, 306 U. S. 102.

3. The application of Carter, at least before the amendments introduced subsequently to the commencement of the present litigation, cannot be construed as embracing structures not conforming to the Abraham formula. And the attempt by amendment to extend the claims, based on the application of the empirical formula (derived from the Abraham formula) to wire lengths not multiples of half-wavelengths, must fail because it involved a departure from what Carter's application had described as his invention, and a contradiction of it. P. 306 U. S. 98.

4. It is unnecessary in this case to decide the further question whether petitioner's structures avoid infringement because the direction of their principal radioactivity is not in the plane of the wires. P. 306 U. S. 102.

96 F.2d 587 reversed.

Certiorari, 305 U.S. 582, to review a decree which modified and reversed a decree of the District Court, 16 F.Supp. 610, dismissing the bill in a suit to enjoin infringements of patents. chanrobles.com-red

Page 306 U. S. 88


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