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RCA v. MACKAY RADIO & TEL. CO.

October 14, 1936

RADIO CORPORATION OF AMERICA
v.
MACKAY RADIO & TELEGRAPH CO., Inc.



The opinion of the court was delivered by: CAMPBELL

CAMPBELL, District Judge.

This is a suit for the alleged infringement of certain claims of five patents as follows:

1. Patent No. 1,623,996 issued to Philip S. Carter, assignor to Radio Corporation of America for radio transmission system, granted April 12, 1927, on an application filed June 25, 1923, of which claims 1, 2, 5, and 7 are in suit. This patent will be hereinafter referred to as the first Carter patent.

 2. Patent No. 1,909,610 issued to Philip Staats Carter, assignor to Radio Corporation of America for electric circuit, granted May 16, 1933, on an application filed March 12, 1930, of which claims 1 to 5 inclusive are in suit. This patent will be hereinafter referred to as the second Carter patent.

 3. Patent No. 1,884,006 issued to Nils E. Lindenblad, assignor to Radio Corporation of America for antenna, granted October 25, 1932, on an application filed September 7, 1928, of which claims 23 to 27 inclusive are in suit.This patent will be hereinafter referred to as the first Lindenblad patent.

 4. Patent No. 1,927,522 issued to Nils E. Lindenblad, assignor to Radio Corporation of America for antenna for radio communication, granted September 19, 1933, on an application filed December 24, 1928, of which claims 9, 10, 19, and 23 are in suit. This patent will be hereinafter referred to as the second Lindenblad patent.

 5. Patent No. 1,974,387 issued to Philip Staats Carter, assignor to Radio Corporation of America for antenna, granted September 18, 1934, on an application filed June 11, 1930, of which claims 1, 2, 3, 4, 10, 12, 15, 16, 28, 34, 35, 36, 38, and 40 are in suit. This patent will be hereinafter referred to as the third Carter patent.

 The first two Carter patents are directed to the subject of impedance matching. The two Lindenblad patents and the third Carter patent are directed to the subject of antennas. I will consider them in the two respective groups.

 The defendant by answer has pleaded the defenses of invalidity and non infringement.

 The title to the patents in suit is in the plaintiff and notice of infringement was properly given.

 There is no dispute as to the construction or arrangement of the defendant's antenna systems, and they are fully described in the agreed descriptions, diagrams, and tabulations of dimensional data comprising plaintiff's Exhibits 7 to 13 inclusive. The antennas which are asserted to infringe are known as V-antennas Nos. 1 to 11 inclusive (two of which have been rebuilt) and certain other antennas known as "dipole arrays." The antennas referred to as having been rebuilt are obviously defendant's antennas Nos. 2 and 3, the rebuilding of which was occasioned by commercial requirements of establishing additional communication channels in a different direction from that in which they had previously been used. Various alterations occurred in the rebuilding process, and as these rebuilt antennas were not rebuilt until after the main and supplemental bills of complaint were filed in this suit, they cannot properly be considered by this court under the charge of infringement on the pleadings in this suit.

 The desirability for, and the utilization of an impedance matching arrangement was known many years prior to the earliest date which could be claimed by Carter. In the transmission of electrical energy over a line, whenever, as is usually the case, the impedance of the load differs from the impedance of the transmission line, energy will not flow smoothly into the load, but part of it will be reflected back into the line towards the source of power, and cause "reflection," "standing waves," "reflection loss," etc. Also, when there is a sharp bend in a transmission line a difference of impedance results which causes reflection. If, however, the impedance of the load is matched to the impedance of the line there are no reflected waves, and there is obtained what is termed a "reflectionless line," "a traveling wave," a "line of electrically infinite length," etc. These terms (as well as others mentioned on the trial and in the briefs herein) are synonymous and the desirability for impedance matching, as well as the means employed for effecting it, is not concerned with the purpose for which the current being transmitted is used. I can see no difference whether impedance matching be effected in a radio receiving system, a radio transmission system, a telephone line, a power line or in any circuit. The second Carter patent in suit is entitled "Electrical Circuit," and is applicable to any circuit arrangement where efficient transfer of energy without reflection is desired. Unequal impedance is always the cause of reflected waves, and the cure is always equal or matched impedance.

 Impedance matching devices for the purpose of preventing reflection on transmission lines have been used for many years in radio transmitting systems, at least, since 1920, and as the first Carter patent in suit was not applied for until 1923, there was nothing novel at that date in the necessity for matching impedances, or in the principle that by matched impedances reflected waves on the transmission line were avoided.

 The first Carter patent No. 1,623,996:

 This patent is directed to the subject of a reflectionless transmission line obtained by matching the surge impedance of the line with the load impedance of the antenna which it feeds. A transformer is the only means shown or suggested for accomplishing that purpose, and two forms of transformers are illustrated namely the usual two coil transformer illustrated in Figs. 1, 3, and 5, and the auto (one coil) transformer of Fig. 2.

 It is pointed out in the patent that in the past it has been the custom to erect the antenna of a transmitting system as close as possible to the point when the radio frequency power is generated in order to have "a minimum power loss between the generator and the antenna." The patentee in his specification states the objects of his invention to be as follows: "The provision of a transmission line which will supply radio frequency energy from a power-house to an antenna located at a considerable distance away, thus making possible the utilization of existing apparatus at a high efficiency where hitherto only a low efficiency was possible. Another object of the invention is to provide a new and improved system giving directional transmission utilizing separate antennae fed from a single source through a plurality of transmission lines."

 Claims 1, 2, and 5 have to do only with the first stated object. Claim 7 has to do only with the second stated object.

 It is pointed out in the specification that in order to attain the first object of the invention it is necessary that the apparatus work "at unity power factor; that is to say that the current and voltage in the transmission line should be in phase," and the patent further says: "Such a result may be obtained if the transmission line is made reflectionless or of electrically infinite length. Under these conditions no waves can be reflected back from the ends to interfere with the natural flow of energy into and out of the transmission line."

 The invention of the patent consists in making reflectionless the transmission line extending between the source of the current and the load. The patentee says in his specification: "This result may be obtained by closing the transmission line 10 at 11 in such a manner that the effective impedance at the load end of the line is equal to the surge impedance of the transmission line."

 This statement means that the impedance of the load is matched to the impedance of the line throughout the entire length thereof.

 The problem as stated is how to bring about or produce that condition.

 The recital by Carter of what purports to be his solution of the problem amounts simply to this: The antenna resistance multiplied by the square of the feed ratio should be equal to the surge impedance of the line.

 This is a statement in terms of results, without any instruction as to how to accomplish these results.The only thing shown in the drawings of the patent for accomplishing the resut is a transformer, but there is no statement, nor is it implied or indicated how the transformer is to be made, adjusted, or set up in order to make it possible to close, "the transmission line 10 at 11 in such a manner that the effective impedance at the load end of the line is equal to the surge impedance of the transmission line."

 The first Carter patent in suit is a paper patent, and in view of the prior art in evidence to wit, Alexanderson patent, No. 1,360,167; Rice and Kellogg patent, No. 1,602,085; Colpitts patent, No. 1,129,959; Leblanc patent, No. 874,411; Heising patent, No. 1,313,483; Conrad patent, No. 1,640,534; Reuthe patent, No. 1,314,095 and Whiting patent, No. 1,537,101, it can be given only a limited range of equivalents sufficient to protect the invention of that patent.

 Defendant does not employ any connection between a transmission line and a radiator, where at the point of connection, an impedance matching device is employed.

 The defendant in every antenna under charge of infringement in this suit employs an impedance matching device located in the transmission line at a distance from the antenna wires.

 No transformer connecting the end of the transmission line with the antenna is used by the defendant in any of its antenna systems under charge of infringement in this suit.

 The defendant does not employ a transformer as an impedance matching device in any of its said antenna systems.

 Claim 1 recites as the elements of its combination "an energy radiating circuit (an antenna), a source of power for energizing said circuit (the generator), and a transmission line of electrically infinite length connecting said circuit and said source."

 Fig. 1 of the patent shows the transmission line 10 extending to the antenna, as is necessary in a system where a transformer connects the antenna with the transmission line, and the patent in suit instructs to terminate the line with a transformer.

 No such arrangement or any arrangement which might be correctly described by this language is shown in any of the defendant's alleged infringing devices.

 This is also true with respect to claims 2 and 5 in suit, the last element in each of which is defined as a reflectionless transmission line connecting the source and the antenna or radiating circuit.

 Antenna No. 2, which is typical of its class, shows that the transmission line extends from the transmitter to the radiators (antenna wires ACBD), but the impedance matching device (KLMN) is located on the transmission line a substantial distance from the radiators, therefore defendant does not employ "a transmission line of electrically infinite length connecting the radiator (ABBD) and the source" (the transmitter).

 Antenna No. 7 of defendant's devices has reflected waves on the entire portion of the transmission line leading from the power house to where the transmission line branches, as well as from the radiators to the points E F and E'F'.

 By their terms each of claims 1, 2, and 5 are limited to a transmission line connecting the antenna and the source of power which is reflectionless throughout its length.

 Defendant does not employ in any of its antenna systems a transmission line connecting the source of current to the radiating antenna which is reflectionless throughout its length.

 In defendant's devices the production of reflected waves on a portion of the defendant's line is a necessary expedient for successful operation and defendant's antenna system could not operate if defendant's arrangement were used in a manner to entirely eliminate reflected waves throughout the length of a transmission line. Defendant's antenna No. 2 (original) best illustrates this point.

 Claim 7 of the patent in suit recites as the elements of its combination: A plurality of antennae; a single source for supplying energy to all of said antennae; and transmission lines of electrically infinite length for supplying energy from said source to said antennae.

 It thus appears that claim 7 is limited in addition to the limitations of claims 1, 2, and 5, to at least two transmission lines of electrically infinite length which supply power from a single source to two or more antennas.

 Plaintiff attempted, but unsuccessfully, to apply this claim to defendant's antenna systems like antenna No. 8.

 From a careful consideration of the evidence, it appears that the defendant's devices, which are alleged to infringe, use a radically different arrangement to accomplish an old result, and irrespective of the validity of the patent in suit or whether or not the claims are readable on defendant's antennas. Westinghouse v. Boyden Power-Brake Co., 170 U.S. 537, 18 S. Ct. 707, 42 L. Ed. 1136.

 The defendant does not infringe the first Carter patent, No. 1,623,996.

 The second Carter patent, No. 1,909,610:

 This patent, like the first Carter patent, is directed to the subject-matter of matching the surge impedance of the line to the impedance of the load to which the line feeds. As its object is identical with that of the first Carter patent, which was applied for nearly seven years and issued nearly three years prior to the application of the second Carter patent, the subject-matter of the said second Carter patent is and must be confined to the particular instrumentalities, arranged in the particular way shown and described by the patent to effect impedance matching.

 The second Carter patent is not specifically directed or limited to use in connection with radio antennas, but to electric circuits in general, and for use in any field where reflectionless transmission lines, matched impedances, elimination of standing waves, etc., are desired.

 The patentee in his specification says: "This invention relates to electric circuits and especially to a transmission line supplying high frequency currents to a high frequency load circuit," and then recites what is well known in the prior art: "In order that the line transmit energy at best efficiency; that is to say, without reflection, it is desirable that the line be terminated by a load which equals in impedance the surge impedance of the line."

 After noting that lines and loads are independently designed, and that existing lines must be connected with existing loads which do not have the requisite values of impedance for best energy transmission, the patentee states: "It is an object of my invention to provide a method and means for terminating a line to which a load is connected so that the termination means combined with the load presents the correct impedance to the line. More specifically, I accomplish this by connecting a variable reactance across the line at a distance away from the load such that the circuit formed thereby including the variable reactance, the line portion between it and the load, and the load, presents an impedance equivalent to the surge impedance of the line."

 On its face the patent admits, in substance at least, that it differs from the disclosure of the first Carter patent only in the specific "method and means for terminating a line."

 The patentee then says: "In a case wherein the surge impedance is greater than the load impedance or resistance, I have discovered that by connecting a capacitive reactance across the line at a distance not more than one-quarter of a wave length of the energy transmitted by the line away from the load; or, by connecting an inductive reactance across the line at a distance more than one-quarter wave length but less than one-half wave length of the load, the combination of the reactance and the load and portion of the line included between the reactance and the load becomes equivalent, with proper quantitative values of the electrical elements involved to the surge impedance of the line, thereby facilitating efficient energy transmission," and then says: "Similarly I have discovered that when the surge impedance of the line is less than the load impedance, by connecting an inductive reactance across the line not more than one-quarter wave length away from it; or, a capacitive reactance across the line more than one-quarter wave length but less than one half wave length away from the load, that the combination of reactance, load and portion of the line included between the reactance and the load becomes equivalent, with proper quantitative values of the electrical elements involved to the surge impedance of the line thereby properly terminating it for maximum energy transmission."

 From the foregoing quotations from the patent, it appears that whether the surge impedance is less or greater than the load impedance, the patentee connects a variable reactance across the line, viz., in shunt to the load. That where the surge impedance is greater than the load, the reactance is either capacitive, with its point of connection across the line "not more than one-quarter wave length * * * away from the load," or it is inductive, located "more than a quarter wave length but less than one-half wave length away from the load." That where the surge impedance is less than the load impedance, the resistance connected across the line is either inductive and positioned "not more than one-quarter wave length away from the load," or is capacitive and is connected across the line "more than one-quarter wave length away from the load." That the desired result is attained under either set of conditions only "with proper quantitative values of electrical elements."

 The specification describes the arrangements shown in the drawings and sets forth in a table the discovery of the patentee recited in the two paragraphs of the patent hereinbefore quoted.

 The disclosure of the patent in brief is that impedance matching may be effected by connecting a variable reactance of proper value across the line at a proper distance from the load. The patent recognizes and twice states that the object of the invention can be attained only "if proper quantitative values of the electrical elements involved" are used, but is silent as to how those values can be ascertained. Further, the patent conveys the idea that at any point within a quarter wave length distance from the load (in the one case), or more than one-quarter wave length but not greater than one-half wave length (in the other case), a reactance connected across the line would obtain the desired result, whereas in ...


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