US1968868A - Radiotower - Google Patents

Description

A. O. AUSTIN Aug. 7, 1934.

RADI OT OWER Filed Feb. 10, 1930 I5 Sheets-Sheet l 1934- A. o. AUSTIN 1,968,868

RADIOTOWER Filed Feb. 10, 1930 3 Sheets-Sheet 2 A TTORNEV A. O. AUSTIN Aug. 7, 1934.

RADIOTOWER Filed Feb. 10, 1930 3 Sheets-Sheet 3 WM ATTORNEY Patented Aug. 7, 1934 1,968,888 RADIOTOWEB.

Arthur 0. Austin, near Barber-ton, Ohio, assignor,

by mesne assignments, to The Ohio Brass Company, Mansfield, Ohio, a corporation of New Jersey Application February 10, 1930, Serial No. t2'l,l28

" 9 Claims.

This invention relates to radio transmission towers and has for one ofits objects the provision of a tower which shall have a minimum effect on the radiation from the supported antenna.

Another object of the invention is to provide improved insulation for the tower.

A further object of the invention is to provide improved means for sectionalizing the tower so as to reduce to a minimum the electrostaticcal pacity of the tower.

A further object is to provide an antenna support which shall be of improved construction and I operation.

Other objects and adi-antages will appear from the following description.

The invention is exemplified in the combina tion and arrangementof parts shown in the accompanying drawings and described in the following specification, and it is more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is an elevation with parts in section showing one form of sectionalizing insulator constituting a part of the present invention.

Fig? is a vertical section of adetail of construction.

Fig. 3 is a horizontal section on line 3-'-'3 of Fig. 1.

Fig. 4 is an elevation partly in section of one cow! the insulating members employed in the insulators shown in Figs. 1 and 3. "I Fig. 5 is a diagrammatic elevation of the complete tower.

Fig. 6 is a diagrammatic view of the top of the tower showing the counter-weight connection for the antenna. r Fig. '1 is a view similar to Fig. 1 showing a slightly modified construction.

In radio transmission towers. the electrostatic 40 capacity of the tower tends to cause an absorption of energy and frequently produces oscillations when thetransmitting frequency approaches the, natural period of the tower harmonies and is also likely to cause oscillation of the tower. This lowers the efiec'tive radiation or distorts the field appreciably. The current ascending in the antenna lead is counteractedto some extent by a current in the opposite direction in the towers. The current descending in the tower will depend upon well known electrical laws.

Insulating the tower by placing insulators at the base of the tower is of benefit, but in general 5, the large electrostatic capacity of the tower to (oil. lit-"251) ground permits current to flow in the tower, particularly where the towers are large in size.

Even though the tower may be very thoroughly insulated at the base, the large electrostatic capacity between the tower and ground will permit of an appreciable flow of the undesirable current in the tower itseli. Any current flowing in the tower tends to neutralize the current in the antenna or aerial so that to obtain a given radiation it is necessary to increase the current in the aerial. This requires an increase in the energy employed without an increase in useful output in radiation. I

Another serious disadvantage due to the electrostatic capacity of the tower is that it tends to increase the electrostatic held about the aerial so that losses from brush discharge may be appreciable. This loss from brush discharge may be reduced by placing the towers at a considerable distance from the live part of the antenna system. Where this is done, however, the towers must be considerably higher, which increases the cost and makes it necessary to obtain greater available space. Where aerials are placed upon buildings, the limited. space is a decided disadvantage in this connection. If the electrostatic capacity of the tower could be eliminated, the tower would have little or no eflectupon the energy losses or the efiective radiation. It is possible to eliminate the effect of the tower to a very great extent by sectionalizing it. Where the tower is cut up into a number of zones using insulators of small electrostatic capacity, the efiective electrostatic capacity of the tower as a whole is greatly reduced so that its adverse eflect upon the transmitting system will be greatly reduced. While it is not possible .entirely to eliminate the electrostatic capacity between the various sections of the tower, cutting the tower up into a number "of sections, is equivalent to placing a number of condensers in series and this greatly reduces the eflective electrostatic capacity for the upper sections of the tower, so that the undesirable current flowing in the tower is reduced very materially. The more completely the tower may be broken up the less will be its detrimental effect. The difliculty of effectively sectionalizing a tower has heretofore been suchthat insulation has been confined almost entirely to the base of the tower where it is generally of least benefit. Where -the sectionalizing o! a tower is to be eflective, it is necessary to provide small electrostatic" capacity in the insulator. This requir es a con-.

parts attached to the end of the insulator will be far enough apart so that the capacitance will be small. This may be accomplished by using insulators made preferably of porcelain to which end metallic members are attached.

Insulators of tubular section provided with a resilient connection are particularly suitable for.

this kind of work, as it is possible to utilize the mechanical strength of the dielectric to a very high degree and at the same time avoid serious stress produced by diflerential expansion and contraction between the metal and insulating member which might otherwise cause the destruction of the dielectric and the failure of the tower.

In the diagrammatic illustrative embodiment shown in Fig. 5, the tower comprises sections 10, 11, 12, 13 and 14 separated by insulators 15, the insulators 15 being shown more in detail in Figs. 1 to 4 inclusive. Each of the insulators 15 comprises a pair of attachment plates 16 and 1'? spaced from each other by interposed insulating members 18. Each of the insulating members as shown in Fig. 4 is formed of a porcelain tube 19- made suificiently strong to support its portion of the load with an ample factor of safety. Caps 20 and 21 are secured to the opposite ends of the tube 19 by means 01' cement interposed be tween the caps and tube, the cement being connected to the tube by a treated sanded surface similar to that shown in my prior Patent No. 1,284,975, issued November 19, 1918. The caps 20 and 21 are secured to their respective attachment plates by cap screws 22. The plates 16 and ll"? are provided with extra perforations 23 for the insertion of temporary or supplemental supports between the plates to take the weight of the tower during its installation or in case of breakage of one or more of the porcelain tubes 19. When the tower is not in use, metal or wood struts of comparatively small diameter may be inserted between the plates and attached at. the openings 23 and will not interfere with the insertion or removal of the insulating supports 19.. The plates 16 and 17 are also perforated for the passage 01' an insulating tube 24 which maybe made of porcelain or other suitable material for conducting gas to the top of the tower. Cork or other suitable packing-25 may surround the tube 24 where it passes through the metal plates to protect it against injury, and suitable unions 26 are provided for connecting the ends of the tube 24 to the metal gas pipe 27. This permits gas to be conducted to the top of the tower for beacon lights to illuminate the tower and the insulating tube 24breaks the pipe up into sections so that it does not interfere with the operation of the antenna. The pipe 27 may also be employed for furnishing gas to burners 28 which heat coils 29 having their lower ends open to atmosphere and having their upper ends connected with pipes 30 which supply hot air through passages 31 to the interior of the tubes 19. In thismanner the tubes may be heated to keep them dry at all times and I maintain efiective-insulation. The plates 16 and 1'7 are attached to the comer members 32 of the tower by means of attachment blocks 33 and joints 34. It should be noted that the brace members 35 are spaced away froin the ends of the corner posts 32 and extend obliquely upward and downward respectively so that the amount of metal adjacent the opposite terminals of the insulators. 18 is reduced to a minimum and a certain amount of resiliency at the point of confineness 'siderable length of dielectric so that the metm nection between the corner posts and the insulators is provided.

In the modification shown in Fig. l, the porcelain tubes 36 are provided with inner reinforcing members 37 which may be made oi wood and secured to their end caps 38. by friction plates 39 and clamping plates-40, in a manner more fully described in my prior Patent No. 1,497,819, issued June 10, 1924. The insulators 36 in this'instance are heated by electrically energized heat coils 41 supplied by storage batteries 42 which are charged from conductors 43 provided with switch membars 44. for opening the circuit across the insulators when the line 43 is not being employed for charging the batteries 42 or for illuminating the tower. The switches 44 are opened during transmission so that the conductor line 43 will not short-circuit the insulators. Instead of a rigid connection between the upper section of the corner post 32 and the plate 17, a pivot-bolt as isprovidedin this case to permit'of a. degree of movement between the insulating section and the tower so that the parts may adjust themselves and thuseliminate unnecessary stresses in the insulator. It is evident that a large sized tower havin members near together, although separated by the insulators, will have an appreciable electrostatic capacity, which tends to neutralize the efiect of the insulators. To obtain a good workmg combination, it is therefore desirable to use a different type or construction from that heretofore used for this class or work. In the particular construction which has been found advantageous, the corner tower members 32 to which the insulators are attached are made sulficiently strong so that they may project beyond the point of atachment of bracing members 35. Cross tie members are omitted in the tower where they would materially increase the electrostatic 11-5 capacity between adjacent zones and thus neutralize the effect of the insulators. This construction has the material advantage that the spring in the comer tower members 32 permits of the installation 01. the insulator without setting up serious stress due to irregularities in the fabrication or warping in the steel members. This construction permits the insulator to be inserted so that the mechanical result is similar to that where the comer members extend directly 5 through and is very advantageous, as it permits of the insertion of dummy or false members, if desired, during erection, at which time the tower may be subjected to very severe shock.

Where the tower design is such that it is neces- 13o sary to prevent a high bending stress, the in-.-

sulator may be attached rigidly to either the upper or lower member 32, and a pivotal connection provided at the other point of attachment,

as shown in Fig. 7. This may be readily obtained by using a single bolt 45'to attach a shoe or other attachment member to one ofthe comer tower members. v

In order to eflectivel'y insulate a tower, it is essential that insulation be maintained under various weather conditions. This is provided by making the upper plates 17 so that they will shed water. Further protection against wetting the surface of the insulator may be provided by additional weather or rain sheds 48. Where a very high degree of insulation is desired at all times, the insulators may be heated by a current 01' hot air allowed to flow through the bushing. In this case, the bases are made so that a. hot current or air may be allowed to flow into the body of the

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