US2644888A - High-frequency antenna - Google Patents

Description

July 7, 1953 J. J. ROOT HIGH-FREQUENCY ANTENNA mm Mm s J .mm mm E f/,Imw .VIP a m m m14 med Jan. s. 1949 H lllrr u ATTORNEY Patented July 7, 1953 UNITED srArrzsl PATENT ePricei aferrarse `HIGH-lrlurzQUENorfmirarme John J. RootNew York, N. gY. y Application January z5, 1949, serial N0. 72,699

1 This invention relates to antennas for vl'ilS'h frequency uses and in vparticular for television and frequency modulation receiving systems where a plurality of stations may belocated in various directions in relation to the receiver.

The use of dipole antennas for the above mentioned purposes is, of course, well known.r It is common to employ twor sets of dipoles, each cut to predetermined frequencies. The smaller dipoles are oriented to the high frequency'attentionsY While the larger are oriented to the lowvfrequency stations and common leads are generally used to connect the antenna, to the 'television receiver. 'I'he present invention has for its object the provision of such an antenna system which has greater sensitivity than that described and which takes the form ofa more unitary structure. The antenna of the instant invention is of further utility in that the high frequency and low frequency elements do not hinder each other in their respective ranges of operation, but, on the contrary, enhance the elciency of the complementary component as will be hereinafterv described.

In the form shown, the antenna combines a dipole and a loop in a series relationship, the loop being formed or connected at the inner ends of the two dipole arms. Thus, a more or less continuous or unitary structure is formed. Means are further provided to orient the loop in respect to the dipole vwithout interfering with the electrical continuity and for the purpose of directing the antenna elements to the proper stations, the loop serving as the high frequency responsive element while the dipole serves as the low frequency responsive element of the antenna. The television band at present covers a range of about 50 to 220 megacycles and the loop and dipole elements respectively serve the upper and lower portions of this band.

An antenna constructed according 'to the instant invention is of further utility in that con-y siderable metal is conserved while nevertheless providing an antenna of extremely high eiiciency. This conservation of metal is of importance and the reduced bulkiness of the structure render it more wind-resistant.

The invention will be further understood from the following description and drawings, in which:

Fig. 1 is a schematic view illustrating the orientation of the antenna elements to the stations to be received.

Fig. 2 is an elevational view of the antenna per se, the dipole being shown broken away.

. scams. `(C1. o-33.51)

- Fig. 3 is a fragmentary `view illustrating the connectionof the loop to the dipole.

Fig'.'4 is a sectional view taken along the lines 4-4 of Fig.' 3. l Fig. 5 is a sectional view taken along the lines 5-5 of Fig. 3.

Referring to Fig. 2, the antenna comprises 'a pair of dipole arms I0 and II which are cut to a predetermined frequency in the low'frequency portion ofthe band to be received. In the present instance,`such low frequency portion may be fromabout to 100 megacycles. As such, the dipole may be cut to resonate at about megacycles.

` The dipole arms are formed with odset ends I2 and I 3 to permit of their connection to bracket I4 wherein they may be oriented as required. Bracket I4 comprises a block of insulation I5. Clamps IB and I'I are connected as by bolts I8 to one side of block I5 while clamps I9 and 20 are connected to the other side. Each clamp has a slot 2I formed transversely thereof so as to provide upper and lower clamp sections which may be independently tightened. Thus, clamp section 23 accommodates vthe offset end I2 of dipole arm I0 while clamp section 24 accommodates one end of the loop 25.

Loop 25, in the form shown, is .a single turn of metal, open, as conventional, at `the loop ends. Loop ends 26 and 2'I are received in the clamp sections 24 and 28 respectively. In order to make the `loop secure within the bracket clamp sections,A tightening bolts 28 and 30 are screwed down so as to secure the ends 26 and 2I. Inthe same manner, tighteningbolts 3| and 32 secure the offset ends I2 and I3 of the dipole.

l A mast 35 serves to support the antenna structure above disclosed. The mast is formed with an upper platform shoulder 36 upon which the block I5 rests. A vertical section 3'I is also provided which rests flatly against the face of block I5, as illustratedin Fig. 5. Bolts 38 transverse block I5 and are received through openings of channel member 39 where they are engaged by nuts 40. In this way, the block I5 and the antenna elements ksupported thereby are made fast to the mast 35.

The antenna of the instant invention is utilized as follows:

Referring to Fig. 1, the loop 25 is pointed at high frequency station 4I by directing one edge of the loop thereat. This is, of course, the normal way of orienting a loop to any particular station. In the form shown, the loop 25 may .be about 22 inches in diameter in order to serve the may be oriented to intermediate points between stations so as to obtain the best coverage as willbe understood. The lead wires 43 and 44 generally comprise the wires of co-axial cable or the like so as to eiect electrical connectionto thetelevision receiver.

It will be observed that the dipole 'may be oriented without disturbing the electrical connection, to" the vloop because of the metallic bracket clamps.' Such; orientation is rendered very4 convenient by virtue of the offset dipole ends which rotate in the respective clamp sections. It is believed that the efficiency of the dipole is particularly enhanced by the physical formation of the loopfwhich appears to function as a matching stub for the dipole.r It is the central position of the loop 'in respect to the dipole which achieves this result. It is understood, of course, that the size of1loop 25 is chosen so that its inductance serves the-high frequency end of the television band generally about 110 megacycles and upwards to 220 megacycles. The loop provides a good response at 110 megacycles and its efficiency appears to further increase at the higher` frequencies; Its matching stub function is found to be' yofparticular utility in Arelation to dipole arms vl() and H when it is constructed according to the approximate dimensions described.

Whatis claimed is:

1. lAn antenna comprising a pair of dipole arms in'a horizontal plane and having one end of each substantially adajcent the other, metallic bracket means in which said ends are rotatably received, and a loop, the ends of the loop being connected to said metallic bracket means so as to be electrically connected to'said respective dipcle arm ends, said dipole arm ends being electrically insulated from each other apart from their connection to said loop, said bracket means comprising an insulating block having a pair of clampingfbrackets on the respective sides thereof, each of said clamping brackets being slotted transversely to form upper and lower clamp sec- 4 tighten said lower clamp sections to prevent rotation when the dipole arms have been properly oriented.

3. An antenna comprising a pair of substantially aligned dipole arms, one end of each being adjacent the other, an insulator connecting said ends, metallic clamping brackets on the respective sides of said insulator, said dipole ends being offset from the remainder of the dipole arms, each of said: clamping lbrackets being slotted transversely to form upper and lower clamp sections, said offset dipole ends being received in the lower clamp sections and being rotatable therein when saidlower clamp sections are not tightened, a loop, the ends of the loop being received in said Aupper clamp'sections, means to tighten the loop -ends in saidvupper clamp sections so as to be supported thereby," means to tighten said lower clamp 'sections after said dipoles have been suitably oriented in respect to said loop, said dipole arms being of a sizevso-as to jointly resonate at approximately megacycles and said loop being a single turn approximately 22 inches in diameter, said loop thereby functioning as a matching stub Vfor the dipole arms.

4. An antenna comprising a horizontal receiving rod and a loop connected at an end thereof so as to be electrically continuous therewith, said rod being swingable in a horizontal plane relative to the loop so that it may be oriented relative to the loop, said loop being disposed in a vertical plane and being vofv afdiameter so as to resonate at a substantially higher frequency than said horizontal receiving rod. v

5. An antenna comprising a pair of horizontal dipole arms having one end of each substantially adjacent the other, a loop connecting said dipole arm ends, andmeans to orient said loop independently ofrsaid'dipole arms, said loop being disposed in a vertical plane and being of a diameter so as to resonate at a higher frequency than said pair of-dipole arms.

JOHN J. ROOT.

Referenees cited in the me of this patent UNITEDl STATES PATENTS 'OTHER REFERENCES Journal of the Institute of Electricaly Engineers, vol. 94, part III, The Development and Study of a vPractical spaced-Loop Radio Direction-Finder for High Frequencies, by W. Ross, page 106, October 30, 1946.

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