US2701308A - Television antenna - Google Patents

Description

Feb. 1, 1955 c, KAY 2,701,308

TELEVISION ANTENNA Filed April 23, 1955 2 Sheets-Sheet l INVENTOR JAMES C. KAY

BY Mai m ATTORNEYS Feb. 1, 1955 J. c. KAY

TELEVISION ANTENNA 2 Sheets-Sheet 2 Filed April 23, 1953 FIG.4

FIG. 5.

INVENTOR ames 0. KAY

FIG.6.

ATTORNEY5 United States Patent TELEVISION ANTENNA James Cecil Kay, Rockmart, Ga.

Application April 23, 1953, Serial No. 350,549

Claims. (Cl. 250-3351) This invention relates to antennas and more particularly relates to antennas for television reception.

At present the ordinary television reception is received through what has arbitrarily been designated as channels 2 to 13 inclusive, comprising a low band of frequencies from 54 to 88 megacycles (with a break from 72 to 76 megacycles for non-Government fixed and mobile applications). which are covered by channels two to six inclusive, and a high band of frequencies from 174 to 216 megacycles covered by channels seven to thirteen inclusive, as is well known. Each of the channels has a different frequency with the ranges of the two bands. Many attempts have been made and are still being made to devise an antenna which will perform satisfactorily on all of those channels; and a principal object of this invention is to provide an antenna which will give improved and better all around reception and performance in respect to all of those channels and others.

Heretofore in certain localities in order to get satisfactory television reception and performance from an antenna on the roof of a building, it has been necessary to provide a Yagi antenna cut to the frequency of a particular channel. With such an antenna its performance on other channels is poor or nil. In this connection another object of this invention is to provide an antenna which performs satisfactorily for all channels and in substantially all localities when mounted on the roof of a building, or in other places; and to provide an antenna which gives improved performance over all of the channels and over the performance obtained by station cut Yagi antenna even in the wave band to which the Yagi is cut.

Another object of this invention is to provide an antenna having the improvements stated above and one which is mechanically sound, sturdy in its parts and assembly, and well able to withstand both normal and extreme weather conditions to which an outdoor antenna is subjected.

Another object of this invention is to provide an antenna of the character stated and one which is foldable into a compact bundle or package for storage and transportation, and at the same time may be installed, erected and oriented quickly and easily.

A further object of this invention is to provide an antenna of the character stated and one with which other similar antennas may be stacked either with the same directional aspect or with a different directional aspect when desired.

Other objects of this invention will be in part obvious and in part pointed out hereinafter.

Broadly stated, an antenna constructed in accordance with this invention includes fanned dipoles which are conical length to 66-72 megacycles in channel 4 and peak to 21 megacycles in band width, covering channels 3, 4 and 5 with frequencies from 60-72 and 76-82 megacycles; and the fan dipole responds to 82-88 megacycles in channel 6 as a full wave antenna. There is also a low band director cut to full resonant length to 82-88 megacycles in channel 6 and which will work as a director on 88-60 megacycles covered by channels 6 through 3. The antenna also includes a double reflector system which concentrates reflected signals on channels 2 and 3 covering 54-66 megacycles and at the same time allows the reflectors for channels 4, 5 and 6 covering 66-88 megacycles to be closer spaced and thus adds to their forward gain. The fan dipole receives the hi-h band of frequencies of channels 7 to 13 covering 174-216 megacycles on har- "ice monic frequencies and there would normally be a cloverleaf response pattern. There is also a full one-half wave director in front of the fan dipole which corrects the response lobes of the response pattern received on the high frequency band channels. The antenna also includes a folded dipole cut to mid high band and a full resonance director for all high band channels, the folded and fan dipoles being twin driven in a manner to provide unusual high gain in the high channels, and by this means additional forward gain is obtained. The specific details of the construction and arrangement of parts will be more fully described hereafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangement of parts which will be more fully described hereinafter and the scope of the application of which will be set forth in the claims that follow.

In order that a clearer understanding of the invention may be had, attention is hereby directed to the accompanying drawings which form a part of this application and which illustrate certain possible embodiments of this invention and in which:

Figure 1 is a perspective view as seen from below of an antenna constructed in accordance with this inventron;

Figure 2 is a top view of the antenna with its front end being at the right and its rear end at the left of the view;

Figure 3 is a front view thereof;

Figure 4 is a perspective view of one possible device for attaching frequency receptive elements of the antenna to the cross bar of the installation;

Figure 5 is a front view of a clamping device whereby the fan dipole may be assembled and secured to the cross bar of the installation;

Figure 6 is a top view thereof;

Figure 7 is'an end view thereof; and

Figure 8 is a front view of the folded dipole and shows one possible means for connecting together the outer ends of the upper and lower rods of the dipole.

Similar reference characters refer to similar parts throughout the several views of the drawings.

For purpose of illustration, the drawings show one possible installation including an antenna embodying this invention. As shown, the installation includes a mast 10 to which a horizontal cross bar 11 is secured by means of a clamp 12.

Seven antenna elements are shown mounted on the cross bar 11 and these include a fan dipole 13, a folded dipole 14 forwardly of the fan dipole 13, two spaced reflectors 15 and 16 for the folded dipole 14 and positioned between the fan dipole 13 and folded dipole 14, reflector 16 also being a director for the fan dipole and hereinafter referred to as a reflector director, a directive reflector 17 to the rear of the fan dipole 13 and another reflector 18 to the rear of the directive reflector 17. In front of the folded dipole 14 is a director 19. These seven elements are secured to the cross arm 11 by means of suitable clamps. For instance, fan dipole 13 may be secured to the cross bar 11 by a clamp 20 such as shown in Figure 5 and the other elements may be secured to the cross bar 11 by means of clamps 21 such as shown in Figure 4. These clamps will be described more fully hereinafter.

The fan dipole 13 comprises three rods on each side of clamp 20, extending normal to the cross bar 11 and in the same vertical plane. There are upper and lower fan dipole rods or elements 13b and on each side. Each of these rods preferably are cut to approximately one-half wave length in the low frequency band and a corresponding multiple wave length in the high frequency band to respond harmonically in the high band. The central rod 13a on each side is preferably about onequarter the length of the upper and lower rods, which latter rods may be 10 feet in length. With these rods it is preferable to have the angle between the center rod 13a and the outer rods 13b and 130 approximately 40. The decreased Q of fan antennas make them useful for covering a greater number of stations with a single antenna. The forward increase in gain over a broad range is more noticeable with an antenna composed of a number of fanned elements as compared with a dipole of folded dipole systems. In this fan dipole, the conical elements responsive to frequencies of the low frequency band and harmonic frequencies in the high frequency band provide broad frequency band reception in both the high and low band channels. Ordinary fan dipole units use one-half or one-quarter wave length elements. By using elements cut to a proper wave length for maximum band width in the low frequency band and covering the high frequency band on harmonics the fan dipole will receive all channels and will have a response curve resembling a clover leaf. By the addition of the directive reflector 17 and reflector 18 and reflector-director 16, which serves as a director for the fan dipole, the lobe of the response curve is sharpened and width and gain are added to the fan dipole system. Proper adjustment of the length of these elements provide peak high gain over the entire low frequency band and shielding elfect on the high frequency band. The result of having the center rods of the fan dipole shorter than the outer rods is to reduce end effect and to aid in the high frequency band.

The folded dipole 14, as shown best in Figure 8, has two upper rods 14a extending in opposite directions from the center clamp 21 and two lower rods 14b spaced below the respective bars 14a and in parallel vertical alignment therewith. At each end of the dipole there is a clamp 22 of electrically conductive material. Each clamp engages the outer end of one of the rods 14a and the outer end of the lower rod 14b therebeneath. The inner ends of the lower rods 14b are directed toward each other but do not meet. The phasing connection conductors 23 and 24 are secured respectively to these inner ends of the rods 14b. The upper rods 14a may be of larger diameter than the lower rods 14b. For instance, the upper rods may be a half inch in diameter and the lower rods threeeighths of an inch in diameter. The length of this dipole from side to side is approximately one-half wave length in the mid high range of the V. H. F. television band, the spacing between the upper rods 14a and the lower rods 14b is approximately 1 wave length and the length all around including both the rods 14a, the rods 14b and the clamps 22 is approximately a full electrical wave length. When, as disclosed above, the upper parts of the folded dipole are of greater diameter rod or tubing than the lower parts, the input resistance closely matches a 300 ohm lead transmission line.

The folded dipole, besides covering more stations each side of its resonant frequency, is a good impedance match to line and gives excellent over-all performance due to wider range coverage.

Parasitic elements 15, 16, 17, 18, and 19 are spaced 2. predescribed wave length in front of and behind the driven elements; in this case the folded dipole 14 and the fanned dipole 13. The addition of the reflectors and directors gives the antenna a higher gain and a unidirectional patsigned and utilized the directive reflector 17 and which is believed to be a completely new and novel idea and have provided a high gain antenna which compares favorably on any channel with a station cut antenna and which maintains all hand performance. The directive reflector 17 is cut to an appropriate wave length to act as a director to the reflected signal from element 18 which is a low frequency band reflector which operates also in the high frequency band on multiple half wave lengths. Element 17 directs the reflected signal from element 18 and provides additional high gain but does not appreciably lower the resistance of the whole system. The directive reflector 17 acts as a half wave reflector on 60-88 megacycles covered by channels 3, 4, 5 and 6 and affects the impedance in such a manner on channel 2 with a frequency of 5460 megacycles as to provide additional forward gain. Fan dipole 13 and reflector 18 are an all band antenna with gain in the high frequency band and good gain in the low frequency band.

Still more gain and directivity is provided by the addition of the reflector 15 and reflector-director 16 which is also a reflector in the folded dipole system composed of elements 14, 15, 16 and 19. These four elements are essentially a 4 element Yagi consisting of folded dipole 14, reflector 15, directive reflector 17, and reflector-director 16. This system is connected to the fan antenna 13 in such a manner that the gains of each of the antennas are additive to the gain of the other and are phased in a manner which provides a good 300 ohm line match.

Phasing is accomplished by using a piece of transmission lead 25 which is cut to a one half wave length in the mid-high band. This lead is connected to the folded dipole connection points 26 and leads back to the fan dipole 13. The conductors 23 and 24 of lead 25 are transposed and connected to the terminals 27 at the fan dipole 13. The transmission lead 28 to the set is con nected at these points 27. Additional terminals 27 are provided for additional lead in take off points or phasing bars take off point.

This antenna stacks well and can be stacked either horizontally or vertically to provide more gain. The type of stacking will depend on the location and terrain and it is unnecessary to explain this fully here since suitable methods of stacking are in common usage at present. The most common stacking of this antenna is with one half wave length phasing bars in the vertical plane.

The spacing of the elements from each other in terms of wave length is understood by the experts who are familiar with the installation of television antennas and need not be gone into fully here. However, it might be said that satisfactory results may be obtained by spacing the directive reflector 17 nine and one quarter inches from the element 18 and twenty-two and one-half inches from the fan dipole 13 and spacing the element 15 seven and a quarter inches from each the fan dipole 13 and the reflector director 16 and spacing the folded dipole 14 ten inches from the reflector-director 16 and four and onehalf inches from the element 19. These distances are not asserted to be empirical and are subject to variation in accordance with the particular location where the antenna is erected and in accordance with the technical knowledge and know-how of the expert who is installing the antenna.

An antenna may be constructed in accordance with this invention which is of completely knock down construction for storage and transportation and at the same time can be erected and taken apart with great facility. This not only applies to the entire assembly but the fan dipole 13 and the folded dipole 14 may also be constructed to be of knock down character. The knock down construction of the entire assembly is obtained by utilizing the clamping device 20 for the fan antenna and the clamps 21 for the other elements of the antenna. The clamping device 20 also permits the fan dipole 13 itself to be taken apart and the clamps 22 permit the folded dipole to be taken apart. Clamps 21 are in effect carriers for the elements.

As best seen with reference to Figures 5, 6, and 7 the fan dipole clamping and assembling device includes a rectangular block 30 of insulating material having a hole 31 therein which permits the block to be threaded onto the cross arm 11 of the antenna. To opposite sides of this block are secured, as by bolts 32, complementary plates 33 and 34 and which are channelled to clamp against opposite surfaces of the rods 13a, 13b and 13c of the fan dipole on both sides of the block 30. When the inner ends of the rods 13a, 13b and are inserted into the recesses or sockets provided by the complementary plates 33 and 34 the two plates may be clamped against opposite sides of these rods by means of screws or bolts 35. The fan dipole assembly may be fastened to the cross arm 11 against rotation thereon by means of set screws 36 which are carried in the insulation block 30.

The other elements of the antenna which are removably secured to cross arm 11 may be attached thereto by clamps such as 21 and which comprise upoer and lower complementary halves 21a and 21b. These halves 21a and 21b are adapted to be applied against opposite sides of the cross bar 11 and against opposite sides of an element, such for instance as element 16, the halves 21a and 21b of the clamps 21 having complementary channels to receive the cross bar 11 and both sections of the elements which are clamped to the cross bar, as shown best in Figure 4 of the drawings. The clamps 21 may be secured to the cross arm 11 against rotation thereon by means of set screws such as 37 on one or both of the sections 21a and 21b of the clamp. The rods of each element on each side of the clamp may be clamped between the elements 21a and 21b by means of screws or bolts 38 which engage and clamp the sections 21a and 21b of the clamp together.

Each of the clamps 22 of the folded dipole 14 may comprise two complementary members having at their upper and lower ends complementary channels adapted to fit against opposite sides of the folded dipole sections 14a and 14b and to be clamped against both elements of the dipole by means of a bolt or screw 39 which engages both sections of the clamps.

Accordingly, the antenna in its knock down condition may consist of a bundle of all of the rods including the rods of the fan dipole All these elements can be packaged together in a very compact bundle for storage and transportation.

The ease and facility with which this antenna may be erected and applied to a mast should be apparent. The antenna is folded in position and placed on the mast. Then the fan dipole elements 13a, 13b and 13c are placed in position. The lead in wire is then attached and the mast is erected. It is recommended that the antenna then be oriented to the station of highest frequency and that this be done carefully since this antenna has a very sharp forward radiation lobe.

To summarize: This antenna has been designed to perform in the deep fringe area and to render satisfactory services on rooftops where station cut Yagis previously have been used. It is a high gain all channel antenna and features long fanned dipoles which may measure feet from end to end and are a conical length to the frequencies of channel 4 and peak to 21 megacycles in band width as a conical element on the frequencies of channels 3, 4, and 5; and responds to the frequencies of channel 6 as a full wave antenna. The element 17 is cut to full resonant length for the frequencies of channel 6 and will work as a director for the frequencies of channels 6 through 3. The directive reflector 17 is a half wave reflector on the frequencies of channels 3, 4, 5 and 6 and aflects the impedance on the frequencies of channel 2 in such a manner as to provide additional forward gain. In the high band channels 7 to 13 covering 174-216 megacycles, the fan dipole receives the high band channels on harmonic frequencies and there would normally be a clover leaf response pattern. The response lobes are corrected by the use of a full one-half wave channel 7, director 15 in front of front of the fan dipole. Additional forward gain is added by the use of a folded dipole 14 cut to mid high band and a full resonance di rector 19 for all high frequency band channels, the folded and fan dipoles being twin driven in a manner to provide unusual high gain in the high channels. The antenna is also completely knock down in construction which is valuable for storage and transportation and at the same time the antenna can be erected and dismantled with great facility and ease.

As many changes may be made in the above construction and assembly and as many different embodiments may be made without departing from the scope of this invention, it is understood that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a limting sense.

What is claimed is:

1. A high gain all very-high frequency channel television antenna responsive in a high frequency band and a low frequency band, comprising, in a single array, a single cross bar, a plurality of elements mounted on said cross bar in longitudinally spaced relation from front to rear, said elements comprising a director, a folded dipole, said director being cut to direct appropriate wave length signals to said folded dipole, a reflector-director, a first reflector, a fan dipole, said reflector-director being cut to reflect appropriate wave length signals to said folded dipole and direct signals to said fan dipole, said first reflector being cut to reflect appropriate wave length signals to said folded dipole, a directive reflector and a second reflector, said second reflector being cut to reflect appropriate wave lengths of signals to said fan dipole, said directive reflector being cut to direct reflected signals from said second reflector to said fan dipole, said folded dipole and said fan dipole being connected together, said fan dipole being cut to approximately one-half wave length in the low frequency band and a corresponding multiple wave length in the high frequency band to respond harmonically in the high frequency band, said folded dipole being cut to mid high band frequencies, said fan dipole and said folded dipole interacting to provide high gain in all said very-high frequency channels.

2. A television antenna as claimed in claim 1, said fan dipole including long fanned dipoles being cut to a conical length to channel frequencies of 66 to 72 megacycles and peaking to 21 megacycles in band width for frequencies of 60 to 82 megacycles, the fan dipole responding to 82 to 88 megacycles as a full wave antenna thereby providing exceptional high gain on frequencies of 82 to 88 megacycles.

3. A television antenna as claimed in claim 2, said reflector-director element constituting a director for said fan dipole at frequencies of 88-60 megacycles.

4. A television antenna as claimed in claim 3, said directive reflector constituting a director for frequencies of 88-60 megacycles, said directive reflector and said second reflector element comprising a double reflector system providing concentrated reflected signals on frequencies of 54-66 megacycles.

5. A television antenna as claimed in claim 4, said reflector-director being a full one-half wave director cut to frequencies of 210-216 megacycles and in front of said fan dipole, and correcting the normal clover leaf response pattern of the fan dipole.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,273 Kearse Sept. 26, 1950 2,268,640 Brown Jan. 6, 1942 2,292,791 Mims Aug. 11, 1942 2,481,801 Valach Sept. 13, 1949 2,532,094 Gonsett et al. Nov. 28, 1950 2,598,005 Lippitt May 27, 1952 2,622,197 Cruser Dec. 16, 1952 OTHER REFERENCES Radio and Television News, October 1950, pages 54,

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