MacKay Radio & Telegraph Co. v. Radio Corp. of America

Background

A company that owned several radio-antenna patents sued its only competitor in the worldwide radio communication business, claiming the competitor’s directional Y-type antennae infringed a Carter patent. The trial court found no infringement and dismissed the suit. The Court of Appeals upheld one Lindenblad patent but reversed as to two Carter claims, prompting Supreme Court review of whether Carter’s patent was valid and whether the competitor’s antennas infringed.

Reasoning

The main question was whether Carter’s patent, which relied on a mathematical relation (from Abraham’s published formula) tying antenna wire length to operating wavelength, covered antennas whose wires were not exact multiples of half wavelengths. The Court explained that Abraham’s scientific formula applied only to wires that contain an integral number of half wavelengths and that Carter’s empirical curve was simply a graphical shorthand of that law. The Court held that Carter’s original disclosure and the scientific basis limited the invention to antennas conforming to that law, and that later amendments improperly broadened the patent to cover wire lengths for which the Abraham formula did not apply. Because the competitor’s antennas used wire lengths and angles outside the formula’s scope, the broader claims were invalid and the competitor did not infringe the properly limited invention.

Real world impact

The decision prevents the patent owner from enforcing an expanded claim that would reach antenna designs not tied to the scientific formula; it leaves the competitor free to use its Y-arrangement antennas and requires patents to match their original technical disclosure.