Lorusso v. Ultra-Hi T. V. Manufacturing Corp.

168 F. Supp. 626, 119 U.S.P.Q. (BNA) 373, 1958 U.S. Dist. LEXIS 3329

Opinion

FRANCIS J. W. FORD, District Judge.

This is an action for infringement of the Lorusso patent No. 2,572,166 and the Lorusso reissue patent No. Re. 23,960 for an antenna system for television. Claim 3, which is the same in both the original and reissue patents, is the only claim in issue. It reads as follows:

“3. An antenna for the reception of signals of frequencies associated with television broadcasting comprising a dipole element providing a continuous conductor bent to form two opposed V-shaped structures, each in a plane, one end of an arm of each V being connected to a corresponding terminal of a transmission line and with the ends of the other arms of the V’s being conductively connected together, with the varied spacing between the arms of each structure serving to broaden the band width and to keep the characteristic center impedance of a 300 ohm transmission line, and with the length of said element corresponding to a one-half wave length of a frequency at the lower end of a channel range which is to be accommodated, in combination with a straight director spaced from the arms of said V’s which are connected to the transmission line, with said director cut to a length which is not more than one-third the over-all length of said dipole element, so that the said director improves the sensitivity of said elemerit at said director’s resonant frequency, while leaving at least two-thirds of said element exposed that cannot be nullified by said director when said element is operating at a frequency other than the frequency to which said director is cut.”

Antennas are an important part of the apparatus for transmitting or receiving television and radio broadcasts. An electric current flowing in the transmitting antenna sets up electromagnetic waves which travel through space at the speed of light. These waves passing over a receiving antenna generate in it a flow of electric current corresponding to that in the transmitting antenna. The receiving antenna is electrically connected to the radio or television receiver. The picture or sound is thus transmitted from the source to the receiving set by means of these waves.

The present patent is particularly concerned with an antenna for use in connection with the ordinary television receiving set. There are several characteristics which are desirable in such an antenna. It should be unidirectional, i. e., it should be strongly affected by signals only from one direction. Thus it can be pointed in the direction of the transmitting station and receive its signals at maximum strength and will not be affected by reflected signals approaching from other directions which would impair the quality of the picture received by causing so-called “ghosts.”

To obtain a maximum transfer of energy from the antenna to the receiver, the impedance of the antenna should match that of the receiver and the line connecting them. Since the ordinary television set is built with an impedance of 300 ohms and the standard connecting line has a 300 ohm impedance charaesteristic, it is desirable to have an antenna with a 300 ohm impedance.

Broad band reception is also sought for in television antennas. Two sections of frequencies in the electromagnetic spectrum have been assigned to television transmission. The low frequency range, from 40 to 90 megacycles, includes channels 2 through 6, and the high frequency range, from 170 to 215 megacycles, includes channels 7 through 13. The best antenna from this standpoint is one which would function equally well at all of these frequencies.

One of the earliest forms of antenna was the so-called simple dipole which consists of two arms of a conductive material extending laterally away from the upper end of the transmission line connecting them to the set. It was found that such an antenna would operate well for a given frequency when cut to an over-all length of approximately one-half the wave length of that frequency and would receive signals strongly from one direction only. However, such an antenna worked well only within the narrow range of frequencies for which it was cut. It produced good results only over a frequency range wide enough to cover a single television channel. When it was operated at other frequencies its performance was much less efficient. To get good reception on two separated channels, it was necessary to use two separate dipoles, one cut to each of the desired channels. These could be connected with a matching stub arrangement such that one was inoperative when the set was tuned to the other or each could have its own separate transmission line to a switching device near the set so that one or the other could be connected to the set as desired.

Several improvements on the simple dipole antenna were admittedly well known before Lorusso devised his particular structure. One of these was the so-called folded dipole, which had a second strip of conductive material parallel to the arms of the simple dipole and at a relatively short distance from them these parallel sections being electrically connected at the ends so as to form a single structure. This antenna would give fairly good reception over a range equal to four television channels. Its particular advantage, however, was that, at least when operated at the frequency for which it was cut, it had an impedance of about 300 ohms and hence very suitably matched the impedance of the standard television receiver. It was also well known in 1949 that the band width of the folded dipole could be broadened by moving the parallel legs farther apart, thus increasing the cross-sectional area between the legs. However, there was a serious corresponding disadvantage in that when the legs were moved apart, the 300 ohm impedance was rapidly lost.

Another well-known development was the use of parasitic elements. The simple or folded dipole electrically connected to the receiving set is known as the driven element. Other strips of conducting material (really additional dipoles), placed in front of or behind the driven element but not electrically connected to the receiving set, are known as parasitic elements. When these are placed in front of the driven element, i. e. in the direction from which the signals are coming, they receive energy from the radio signal and re-radiate it in the direction opposite to that from which the signal was received. When they are placed at a proper distance from the driven element so that the re-radiated signal is in phase with the current produced in the driven element, that current is reinforced. Such elements are known as directors. They are usually cut slightly shorter than the driven element. A reflector is a similar parasitic element usually cut slightly longer than the driven element which receives the radio signal and re-radiates toward the driven element to additionally reinforce the signal received by the driven element. These parasitic elements also serve to increase the directivity of the antenna. A combination of a driven element, either a simple or a folded dipole, with one or more parasitic elements, is called an array.

With this background in mind, the Lorusso antenna can now be described. It is an array consisting of a dipole, a conventional reflector, and one or more directors. The dipole is a modification of the folded dipole having what he calls a bat wing shape. (Actually it has no resemblance to the shape of a bat’s wing.) This bat wing is made up of two V-shaped structures, one end of an arm of each V being connected to a terminal of the transmission line with the ends of the other arms being joined conductively. It can also be pictured as having the shape which would result from pulling back the center of the rear parallel leg of the conventional folded dipole so as to give the folded dipole a triangular rather than a rectangular shape. The final structure is also described as having the front portion con-caved toward the front of the antenna. This dipole is cut to the length of a half wave length corresponding to one of the frequencies in the lower range of television channels. The director or directors are cut to a half wave length of one of the frequencies in the upper range, such that the length of the director is not more than one third of the length of the bat wing dipole.

Lorusso’s claim to invention consists in his contention that he was the first to use a combination of a driven element cut to a low frequency with a director cut to a high frequency and not more than one third of the length of the driven element to produce an antenna which would give uniformly good reception over the whole range of television channels. His theory is that when the antenna is operated at low frequencies the director is ineffective and the bat wing dipole operating alone gives good reception, while at the higher frequencies the director comes into play to reinforce these frequencies and thus insure good reception.

It seems clear that there is no invention in the bat wing dipole alone. The testimony of the experts for both parties is in general agreement that in mode of operation and in efficiency it is the equivalent of the conventional folded dipole. Indeed there was evidence indicating that in some situations it operates less efficiently. What Lorusso seems to claim for his peculiar form of folded dipole is that it broadens the band width while preserving the characteristic .300 ohm center impedance. There is nothing to indicate that the bat-wing shape as such has any effect on broadening band width. This results according to accepted theory from separating the legs of any folded dipole so as to increase the cross-sectional area enclosed by the legs. It is the size of this area that is important, not its shape, or whether the distance between the legs is uniform or varies along the length of the dipole. Moreover, the chief advantage of the folded dipole is the 300 ohm characteristic impedance. Broadening the band width by separating the legs is offset by the loss of this 300 ohm impedance. Further, pulling back the center of the rear leg of a conventional folded dipole to change it to a bat-wing shape causes it to approach in shape and at a certain point in characteristics to a loop antenna, which is omnidirectional and hence not suitable for use as an antenna with the ordinary home television receiving set. Moreover, tests conducted by defendant of the comparative efficiency of the bat wing and conventional folded dipoles showed that while the bat wing dipole used alone gives at some frequencies a slight improvement over the conventional folded dipole, this advantage disappears when they are mounted in an array with parasitic elements.

If there is any invention, therefore, in Lorusso’s antenna, it must be found in the combination of a driven element (Lorusso’s bat wing or its equivalent, the conventional folded dipole) cut to a frequency in the lower range of television frequencies with a director cut to a frequency in the higher range, the director being not more than one third of the over-all length of the driven element.

Although, as has been pointed out above, it was the most common practice in 1949 to construct arrays having directors just a little shorter than the driven element and reflectors just a little longer, nevertheless the use of parasitic elements of a fraction of the length of the driven element to broaden the band width of reception had already been pointed out. For instance, Wintermute’s patent 2,471,256 shows the use for this purpose of reflectors cut to three different frequencies. The Kearse antenna, patent 2,474,480, has two conventional folded dipoles, the shorter one placed in front of the longer, which together with a reflector form an array physically resembling the Lorusso array. However, the mode of operation here is different since the two dipoles are connected by a transmission line and they are so cut that the longer acts as the driven element for reception of frequencies in the lower frequency range and the shorter as the driven element in the higher frequency range.

The Brown patent 2,268,640 shows an array of a driven element (a simple dipole) with two directors and two reflectors, one director and one reflector being cut to a frequency one-half that to which the other director and reflector and the driven element are cut. The Brown antenna contains substantially all that is found in Lorusso, together with other elements adapted to Brown’s particular purposes. Brown was interested in developing an antenna for use in transmitting and receiving on two specific and related frequencies. Hence he also included a matching stub not found in Lorusso. In Brown this stub served to increase frequency sensitivity and precision at the two specific frequencies on which Brown desired to operate. This was especially desirable in Brown since his antenna was designed for transmission as well as reception. Such use of matching arrangements was well known in 1949, as was the fact that they could be omitted when such effects are not needed. Brown, of course, has two directors and two reflectors to increase directivity, but he specifically pointed out that some of these could be eliminated as desired. Brown shows a simple dipole as his driven element. It was also well known in 1949 that the folded and simple dipoles could be used interchangeably in different arrays, and Lorusso’s bat wing, as has been pointed out, is the equivalent of the conventional folded dipole.

Brown also shows his short parasitic elements cut to one-half the length of the driven element, while Lorusso specifies that his director is to be less than one-third the length of the dipole. Brown, however, points out that his specific dimensions are given merely by way of illustration, and that his principle is that the relative size of the elements is determined by the wave lengths of the related frequencies at which he desires to operate. This relationship could be one to three just as well as one to two. The one to three ratio is as a practical matter the one which would be natural to use for Lorusso’s purposes since a typical frequency in the upper television frequency range would have a wave length of about one-third that of a typical frequency in the lower range. The experts testifying on both sides agreed that the principle of operation was exactly the same whether the director was one-half or one-third the length of the driven element. Moreover, Lorusso himself, in applying for his reissue patent, sought to expand his claims to include directors cut to one-half the length of the driven element, indicating that he himself did not consider the specific length of one-third as being a distinctive element of his antenna.

In summary, Brown clearly discloses what is the essence of Lorusso’s claimed invention, that is, the use of a short director, cut to a higher frequency than that for which the driven element is cut, in order to enhance receptivity of the antenna at the higher frequency.

In an article “Antenna Design for Television and FM Reception” by Frederick A. Kolster, 1948 Proceedings of IRE 1242, an antenna system is described having what the author describes as two dipoles. One of these is clearly the driven element and, as has been pointed out before, the substitution of a folded dipole for a simple dipole as the driven element was obvious in 1949. The other dipole cut to one-third the length of the driven element corresponds to Lorusso’s short director. Kolster does not call it a director, but directors are often called dipoles and in fact a director is a dipole which differs from the driven element in not being connected by a transmission line to the receiving set. However, plaintiffs argue that since there is considerable capacitance between these two dipoles, this means that there is a mutual coupling between them which makes the smaller dipole a part of the driven element rather than a director. However, plaintiffs’ expert testified that such mutual coupling exists between any two close conductors and hence to some degree is present in all antenna arrays. While in Kolster it may have been present to a greater degree than in other antennas, Kolster nevertheless shows Lorusso’s fundamental idea of the use of a director cut to one-third the length of the driven element. Plaintiff also points out that Kolster’s drawings show his array vertically oriented with the director above the driven element. Nothing is said in the article about this arrangement and it may have been done merely to show the structure more clearly. In any event it required no great skill to rotate the array 90 degrees to bring it to a horizontal level in the proper plane to receive a television signal.

In summary Lorusso shows nothing that was not already found in the prior art, especially in Brown and Kolster. These show clearly the use of a combination of a driven element cut to one frequency with a director cut to a fraction of the length of the driven element for the purpose of broadening the range of reception. Consequently Lorusso’s Claim 3 of both patent 2,572,166 and reissue patent 23,960 must be held invalid for lack of invention over the prior art.

Judgment will be entered for defendant in accordance herewith.