US2710916A - Television antenna - Google Patents

Description

June 14, 1955 Filed Sept. 29, 1950 R. M. JONES ET AL TELEVISION ANTENNA INVENTOR. RUBEET M. JONES ARTHUR E. SEGAL 8 JOHN L. HOELLER/CH THE/R ATTORNEY nite 2 States Patent Ofiice TELEVISION ANTENNA Robert M. Jones and Arthur A. Segal, Chicago, and .Iohn L. Hoellerich, Wilmette, 11]., assignors to Admiral Corporation, Chicago, Ill., a corporation of Delaware Application September 29, 1950, Serial No. 187,454

4 Claims. (Cl. 25033.51)

This invention relates to antennas for television receivers, and more particularly to what is termed an inside television receiver antenna.

It will be recognized that for best television reception, particularly at a distance from the transmitter, that a television antenna should be mounted high enough to provide line of sight reception. It so happens, however, that, in order to accomplish this, these antennas are most usually installed on the roof of the dwelling. This, to some people, is objectionable, from the standpoint of appearance and the difficulty of installation. It also frequently happens that, in apartments, the owner does not want these antennas on the roof because the installation is liable to damage the roof.

It therefore becomes desirable to provide an antenna that may be mounted in proximity to the receiver. Some of these are designed to be placed on top of the receiver. This detracts from the esthetic beauty of the receiver which is usually designed with a certain period motif in mind.

Therefore, it is most highly desirable to design an inexpensive antenna which may be concealed. within the cabinet itself.

Because of space limitations, such an antenna is difficult to design or construct, for as is well known, the simplest form of television antennas comprise the well known di-pole which, when out from the lower television band, should be approximately 80 inches long, it usually being cut to receive the weakest lower television channel.

Another difficulty with a television antenna inside the cabinet is that most antennas that will receive these high frequency stations are highly directional. Ordinarily an antenna built into the set can only be oriented with the station by turning the cabinet so that the antenna inside the cabinet is broadside to the station. It may so happen that for reception the cabinet would have to be so turned that the audience could not readily view the picture.

By the present invention an antenna is made which operates satisfactorily in a great many locations and wherein the antenna is concealed within the cabinet. Furthermore, although the antenna is directional, it can be adjusted so that a minimum amount ofmovement of the cabinet is necessary in order to obtain the best results.

The adjustment is so simple that, with a minimum of simple instructions, the ordinary person may adjust the same to provide the best picture. Being installed in the set, unsightly lead-in wires outside antennas and the hazard from lightning are completely eliminated.

For a better understanding of the invention, reference may be had to the accompanying drawings illustrating an embodiment thereof:

In the drawings:

Fig. l is a plan view of the antenna of the invention;

Fig. 2 is an enlarged section along the end 22 of Fig. 1;

Fig. 3 is a diagram showing the effective antenna in one position of the switch;

Figs. 4 and 5 are views showing alternate effects; and

Fig. 6 is a diagram showing the actual electrical type of antenna.

In the drawings, like parts are designated by like reference characters.

Briefly, the invention comprises a pair of dipoles which are relatively short for the high frequency band and may be loaded so that they may be useful in the low frequency television band. The dipoles are disposed substantially diagonally to each other so that they are directional in directions between and degrees apart. A matching stub is provided which enables the dipoles to operate in the low frequency band and the dipoles are selected by a switch which enables either set of dipoles to be selected, or the switch may be positioned so that all the dipoles are connected and the antennas become a fan or cone shaped antenna.

More specifically, a base 10 is provided which may be of a suitable insulating material and ofa size and shape which enables it to be placed in the top of a cabinet where it may be secured by screws or rest on ribs adjacent the top and on the side. Preferably, the base is square or rectangular. The elements which form the dipoles each comprise strips of conducting material 11a-d which may be metal, secured to the base by rivets or may be conductive paint. Each strip extends from a corner of the base toward but to one side of and spaced from the center. The inner ends of the strip are also spaced from each other.

It will thus be seen that the diagonally opposite strips of each pair each comprise a dipole, the arms or elements of which are parallel to a common center line and the inner ends being spaced apart.

The inner ends of each dipole have secured thereto, by rivets 12, contact clips 13, each of which are provided with spring tongues 14 having a bowed part 15 to give it the desired resilience. An upwardly extending part 16 at the end enables a switch blade to be easily moved underneath, between the fingers and the base for making contact. It will be appreciated that this also adds to the length of the dipole elements.

The spring fingers on the strips, secured to adjacent corners of the opposite dipole elements, extend toward each other and are spaced apart a distance less than the width of the switch blade, so that the blade can be made to contact with either one or the other or both of them.

The switch blades and the operating handle therefore are so mounted that either pair of diagonally opposite sets of dipole elements can be selected by moving the switch between its extremes of movement or an intermediate position may be selected wherein all four of the elements are connected to the transmission line.

In carrying this out, a handle is provided which is pivotally secured to the center of the board by a rivet 19. Secured to the handle on opposite and under sides thereof by rivets 21 are metallic strips 20. One of the rivets on each strip carries a solder lug 22a and 22b by means of which a connection may be had to a transmission line 24.

It will be noted that the mechanism is illustrated with the switch handle 18 in the mid-point position. In this position, one side 2211 of the transmission line is connected to two strips of adjacent sides, such as 11a and 11b, while the other side 2212 is connected to the strips and 11d.

In this position the antenna may be considered as a fan antenna as per the diagram of Fig. 3.

Patented June 14, 1955 When the switch arm is rotated clockwise, as viewed in Fig. 1, the contact strips 20 will be connected to the strips 11a and 11d and the device will then present an antenna as shown in Fig. 4, this being the extreme clockwise movement of the switch since the blades 20 bottom by either striking the elements lla-d or bottom in the clips 13. Here again it will be appreciated that the switch blades also add to the length of the dipole elements.

Extreme rotation of the switch arm in a counter-clockwise direction provides an antenna which is rotated approximately 60 or 120 degrees, the switch blades being connected to the elements 11cd providing, of course, the elements 11a and 110 are angularly displaced from each other 60 degrees which is substantially the angle shown in the drawings.

It will be apparent that this angle of displacement may be varied, and that the maximum angle would be 90 degrees, in which event the switching between the extremes of movement would provide a directional vari ation of 90 or 180 degrees, this being due to the fact that each antenna is a dipole and is therefore directional in either direction broadside to the antenna.

It will thus be seen that with a cabinet itself, with the antenna installed, it is possible, with the combination of movement and the switching of the antennas, to operate the receiver most efficiently, regardless at which point of the compass the station is located relative to the receiver.

The antennas electricially are all the substantially equivalent to the diagrammatic showing in Fig. 6, and each 5 comprises a dipole to which a transmission line 24 is connected.

In order that the antennas be useful in both of the present television bands, a shorted stub 30 of transmission line is secured to the dipole. The length of the stub will depend on the low frequencies to be received since it loads the antenna itself which is essentially an antenna in the high frequency band, so that reception may be had on the low frequency band.

It has been found that with the present band alloca tion for television, that if the elements 11ad are each made 10 inches long and the stub 24 inches long, with the transmission line connected to the stub 11 inches from the end, a very satisfactory antenna is realized.

Preferably, the transmission line is 300 ohm line and the stub is also made of a 24 inch section of 300 ohm line. The elements 11 being approximately 10 inches long together with the switch fingers and the blades, combine to make an antenna having an effective length of approximately 13" in each element which, as is well known,

is effective for the channel 13 (210-216 mc.). The length of the stub, then, is such that it has no effect on the antenna at this higher frequency. It will be appreciated that this antenna is a compromise to enable the best reception to be obtained over two ranges of frequencies within certain space limitations.

In the low frequency band, the stub becomes effective to load the dipoles, thus increase electrically the length. In this instance, the lead-in or transmission line being connected ll inches from the stub end, the entire stub including the 13" between the lead in and the arms of the dipole, being 24 inches, loads the antenna for channel 5 (76-82 me.).

It will be appreciated that under certain conditions the dimensions may be varied. For instance, the stub may be 47" and the transmission line connected into the stub 11" from the end to provide the same loading for the low channels. This gives the increased benefit of a longer distance from the antenna which is useful in certain types of cabinets where space considerations require a longer lead to the antenna terminal.

Having thus described our invention, we are aware that numerous and extensive departures may be made therefrom without departing from the spirit or scope of our invention.

I claim:

1. A television antenna for disposal inside of a television receiver cabinet and comprising an insulating sheet of material adapted to be secured inside the cabinet, pairs of dipole antenna elements disposed on said sheet and including bands of electrically conductive material extending from the corners of the sheet toward and spaced from the center and each other, each pair of diagonally opposite bands constituting a dipole being directional broadside thereto and normally broadly resonant over a television band of frequency, a transmission line and means to connect either one of said dipoles or both of them to said transmission line comprising a switch including spaced apart conducting elements each of which is of sufficient area to connect with both adjacent dipole elements when positioned intermediate said elements and which is mounted for rotation to engage either one or the other of said elements, and a matching stub for resonating said dipoles in a band remote from the fundamental to which the dipoles are normally broadly resonant.

2. A television antenna for mounting inside of a television cabinet and including a sheet of insulation material of rigid formation, pairs of dipole elements mounted on said sheet each pair comprising thin conductive metal strips extending in spaced relation to each other and in angular relation to the other pair, contact means comprising thin flexible fingers extending from each element of the angular spaced elements on one side of the support toward each other in oppositely disposed spaced relation to provide pairs of contact elements in spaced parallel relation, a switch means for cooperation with said contact means comprising an insulating member pivotally mounted in the space centrally located between said pairs of contact elements and carrying switch blades extending from each side in opposite directions, said blades having the ends of a transmission line connected thereto being movable under said contact fingers to connect either one or the other of said dipoles to said transmission line and of a width sufiicient to bridge said opposite contacts of each pair to connect said angularly spaced elements to each other and said transmission line, and an extension for said pivoted member extending beyond the support to provide an operating handle.

3. A television antenna adapted to be placed inside a television receiver cabinet and comprising a base of insulation material adapted to bridge the sides of a cabinet, oppositely disposed pairs of dipole elements each comprising thin strips of metal secured to said base in angularly spaced relation to each other, each strip of a pair being adjacent the other, the ends of said strips being spaced apart and having contacting surfaces formed thereon, a movable contact member disposed between the ends of the strips and arranged to engage the contacting surfaces of an adjacent pair of metal strips or to selectively engage one strip of each oppositely disposed pairs of metal strips.

4. A television antenna adapted to be placed inside a television receiver cabinet and comprising a base of insulation material adapted to bridge the sides of a cabinet, oppositely disposed pairs of dipole elements each comprising thin strips of metal secured to said base in angularly spaced relation to each other, each strip of a pair being adjacent the other, the ends of said strips being spaced apart and having contacting surfaces formed thereon, a movable contact member disposed between the ends of the strips and arranged to engage the contacting surfaces of an adjacent pair of metal strips or to selectively engage one strip of each oppositely disposed pairs of metal strips, and arm means attached to the contact member and extending beyond the confines of the cabinet for operating the contact member.

(References on following page) 5 References Cited in the file of this patent OTHER REFERENCES UNITED STATES PATENTS Electronics, January 1950; page 74, 25033TV. 1,424,365 Loftin et a1. Aug. 1, 1922 Radio and Television Retailing, September 1949, 2,259,628 Fener et a1. Oct. 21, 1941 5 250-33TV. (Received in Patent Office September 12, 2,368,286 Carlson Jan. 30, 1945 1949, page 87.)

2,552,816 Root May 15, 1951

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