US2552816A - Directional antenna system - Google Patents

Description

y 1951 J. J. ROOT DIRECTIONAL ANTENNA SYSTEM Filed Oct. 22, 1949 Patented May 15, 1951 "UNI TED PATENT CE DIRECTION-AL ANTENNA SYSTEM John J .rRoot, New York, -N. Y. "Applicatiomoctober 22, 1949; 'Serial No.-123;il22

6 Glaims.

This invention relates to high frequency antennasfor use in televisionandfrequency modulation receivers.

In the art of television reception, as'presently known, it is almost essential to employ a direc tiveantenna which is furtherlof a size to resonate approximately within the frequency range of reception. When the television receiver is in .a so-called fringearea, a term referring to areas "at ,a substantial distance from the televisionytransmitter, it issgenerally necessary to employ a, more or. less, elaborate antenna having elements of adequate size: tOlGSOITlQJZBTatLfihI-B de- .:sired ifrequencies. :When the rreceiver is closer xtothe televisionrstation, lthexa-ntenna maybe correspondingly.simplified:although it is rare. in

actual practicexthat oneimayibe dispensed with :entirely.

Theneed'for'a simple, smalltantenna for television receivers located ;in1l arge cities-has been very great. A'major. reason is that the population of such large cities ioften inhabit. apartment houses" where the use of;a great. number of individual, elaborate antennas is inconvenient, if not impossible. Furthermore, the provision :of a smaller, simplified antenna obviously ofiers con siderablemanufacturing and installation economies. Asa result of the above need, there have been developed antennas which .are disposed withinthe televisionreceiver cabinet;but,:as far as I am aware, suchwantennas have been extremely ineificient. Inaaddition, it was often necessaryto, orient the antenna in ordertoiniprove reception, and the physical orienting of the cabinets was then necessary. It will belevident that this may be very impractical since the cabinet may berequired to. be so turned that the viewing tube is :directed away from the spectators.

With the above in mind, It-have devised an antenna to be incorporated inia television cabinet whichais of pronounced efficiencyand provides a usable signal within reasonable distances from the television transmitter. The. instant antenna employs crossed dipoles,=as will hereinafter ap- ('CL- 25 0-v33-51) 2 i :so that-the: cabinetvjitself need :notvbe. moved :at -all. Orientation of thexantennaiis:thenuaccomplishediby means: of;-a knobidisposedon .the; cabinet which rotates the condenser 1'otor -and*effectively orients the antenna.

'iTheantenna of,theinstantfinvention may also be constructed without itherappendix sabove referred to butwmay. utilize insteadz a matching stub as will behereinafter made; clear.

The inventionwilkbe :further:understoodr'irom the following-3description andv drawings in which -Fig. leis aperspective view Z'OfFiiYJEEIBViSiOII receiver cabinet equipped with the built-in antenna 1 of .the :instant L invention.

Fig. 2 is arragmentarya viewtaken :su-lastantially U along- ;the lines ;2- -2 of: Fig. :1.

Fig; 3 is a fragmentary plan :view lZOf'?:9/i terminal end of i one of theantenna: dipoles.

Fig. 4 is a substantially:schematicillustration of 1 the-antenna installation-- of a Fig. 1.

;Fig. '5 illustrates 'armodification .ofzxthe antenna dipoles-support.

The cabinet 0 illustrates -.a;conventiona1- televisioncreceiver "cabinet .but it will: be evident; that it maytassume manydiverse'forms. in-the term shown; the antenna; .compriseadipole sections l l .and. I I forming one dipole and dipolesections- !2 and i3 forming "another 4(1113018. The dipoles are maintained-in crossed relationship {so i that .they are. perpendicular in relation .-.to each other. For: convenience of handling andinstallation; the .dipole. sectionsare-fastenedasby-stap1es t4 to minsulatingaboard 15. Board lfi maybetof cardboard or: any of the well-known plastic :materials ...genera1l-y used forrinsulation purposes. Board l5 may. be. fastened-ate ,the cabinet: ceiling by. means of .nails or. screws! 6.

.In the form :shown, dipole sections bland #3 l are .bridged by an" elongated conductor. IT which may be -'integral=;-withthe dipole sections I-E! and l3. ,It...has been: found that such. bridging or short ,circuiting increases the, impedance.- match between the, antenna and the ,receiverinput and further increases. gain at the; low .,frequencies.

The dipole sections andbridging-conductor 1 ll may .take.,the,f0-rm..0f flat: metalpstrips-asillustrated. Theaterminal ends .T ;of thedipolesections are. formed as illustrated in Fig. .3 by means tofna slot 18 and hole [9, the sloteliltpermitting .theuterminal end-to be bent. downwardly as illustratedl in. Figs. -llandv2 so -as ,to provide alug-to .Which..soldered connections may. be made. The hole is serves .its usual vfunctiontof permitting .the initial .introductionflof wireslfi and '2! ,;pre ,paratory .to.,solderin-g Ythem ..thereto.

No. 72,700, filed January 25, 1949, but it may further take the improved form illustrated herein.

Wires 29, 2|, 22 and 23 are effectively respectively connected to wires 25*, 26, 21 and 28 which are in turn connected to the lugs 29, 39,- 3I and 32 of the condenser stator plates 33, 34, 35 and 36. Thus, each condenser stator plate represents one dipole section. Condenser 25 may be mounted within the cabinet in any conventional manner, the condenser shaft 31 extending therethrough so that an actuating knob 38 may be employed to operate the condenser, as will be hereinafter described.

To the shaft 31 are'connected two rotor plates 39 and 49 having capacitative action with the stator plates. It will be recognizedthat rotation of the plates 39 and 49 will serve to select input voltages from any particular diametrical position of the stator plates. 'In this way, rotation of the rotor plates acts as quadrant selection in respect to the dipoles to which the stator plates are connected.

Lugs 4i and 42 are respectively connected to the g rotor plates 39 and 49 so that wires 43 and 44 represent the output of the antenna and are correspondingly connected to the input of the television receiver. Terminals 45 and 46 represent such receiver input'terminals.

A particular'advantage is derived by connecting a metallic conductor 41 to either one of the rotor plates or the terminal represented thereby. Thus, conductor strip 4'! is connected to terminal 46 and it is made fast to the backboard 48 of the television receiver as by staples l4. Because of the physical appearance of conductor strip 41, I have referred to it as an appendix. Strip 41 is very useful in increasing the gain of the antenna, particularly for the low frequencies. Referring to Fig. 4, I have further illustrated the provision of a lug 49 which is connected to strip 41. It has been found that further'gain is accomplished by clippingthe strip 41 to the conventional power line cord of the receiver at any convenient point. Lug 49 is therefore provided to facilitate such clipping. It is believed that capacitative action between strip 41 and the ground wire of the power line cord is responsible for such increased gain.

In. Fig. 5, I have illustrated the same essential antenna structure except that the board l5 is replaced by a central insulating member 59, the dipole sections being stapled thereto and thereafter being loose or hanging. With this construction, the dipole sections are merely nailed or stapled directly to the cabinet ceiling.

The operation of the antenna system described will be apparent from the above explanation. Briefly, the directional dipoles accommodate signals received from an direction. The signals are then selected through rotation of the variable condenser so as to effectively orient the antenna in space, although it is physically motionless. The conductor I which connects the free end of one of the dipole sections to the free end of an adjacent dipole section appears to exercise an in- 4 ductive effect so as to compensate for the short ness of the dipoles. Conductor strip 41, which is connected to one of the rotor plates, may be of a length approximately equal to either of the dipoles but such length is not critical.

The use of appendix conductor strip 4'! may be supplanted by a conventional matching stub connected between terminals 45 and 46. Such matching stubs are well known and are generally U- shaped. Connections to the receiver input may be made along respective points of the arms of the U, such points being selected pursuant to the impedance of the receiver input to be matched. However, neither the appendix conductor strip 41 nor a matching stub is essential to the operation of the antenna system and may therefore be eliminated in constructing a satisfactory antenna.

Details of construction of condenser 25 are not included nor claimed herein. However, the condenser may follow the form described in my prior application as aforesaid but may preferably take the form of a condenser which is the subject matter of a patent application being filed herewith.

Whereas I have referred to the action of the rotary condenser as effectively rotating the dipoles, the condenser inherently embodies other functions and advantages such as properly phasing the picked-up signals although they may be arriving at the antenna out of phase In addition, it is believed that the condenser provides a tuning action which increases gain.

What is claimed is:

1. A television antenna system comprising a pair of directional elements disposed so as to be efiectiv-e in substantially mutually perpendicular directions, variable means for electrically combining the outputs of said directional elements so as to effectively orient the pair of directional elements, the end of one of said directional elements being connected to an adjacent end of the other directional element.

2.A television antenna systemcomprising a pair of dipoles crossed so as to be effective in substantially mutually perpendicular directions, the terminal ends of said dipoles being adjacent each other, variable condenser means connected to said terminals for effectively rotating said dipoles in space, an outer end of one of said dipoles opposite to a terminal end thereof being connected to an outer end of the other dipole.

3. A television antenna system comprising a pair of dipoles crossed so as'to be effective in substantially mutually perpendicular directions, the terminal ends of said dipoles being adjacent each other, variable condenser means connected to said terminals for effectively rotating said dipoles in space, an outer end of one of said dipoles opposite to a terminal end thereof being connected to an outer end of the other dipole and a conductor extending from said variable condenser means and being a lengthapproximately equal to said dipoles.

4. A television antenna system comprising a pair of dipoles crossed so as to be effective in substantially mutually perpendicular directions, a rigid support for maintaining said dipoles in crossed position, the terminal ends of said dipoles beingadjacent each other centrally of said support, a condenser including four stator andtwo rotor plates, said rotor plates being arcuate and jointly forming a circle while being insulated from each other, the terminal ends of each dipole being connected to diametrically opposite stator plates, said rotor plates being adapted to provide voltages by capacitive effect from said stator plates for connection to the input terminals of a television receiver, and an elongated conductor effectively connected to and extending from one of said rotor plates, said-elongated conductor terminating in a free end.

5. A television antenna system comprising a pair of dipoles in the form of electrical conductors and crossed so as to be effective in substantially mutually perpendicular directions, said conductors being flexible, supporting means for maintaining said conductors in said crossed relationship, the terminal ends of said. dipole conductors being disposed adjacent each other, an electrical conductor extending linearly and connecting the outer end of one dipole conductor opposite its terminal end to the outer end of the other dipole conductor, and variable condenser means comprising four stationary condenser plates, each of said condenser plates being respectively connected to the four terminal ends of the two dipole conductors, said variable condenser means further including a pair of rotor plates for electrically rotating the directional characteristics of said crossed dipole conductors.

6. A television antenna system according to claim 5 and including a conductor electrically connected to one of said rotor plates, said lastnamed conductor being of a length approximately that of said dipole conductors.

JOHN J ROOT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,188,649 Carter Jan. 30, 1940 20 2,190,816 Wheeler Feb. 20, 1940

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