US2705737A - Transmission line support - Google Patents

Description

April 5, 1955 H. BRUECKMANN TRANSMISSION LINE SUPPORT 2 Sheets-Sheet 1 Filed Jan. 9, 1951 INVENTOR. HELMUT BRUECKMANN April 5, 1955 H. BRUECKMANN 2,705,737 TRANSMISSION LINE SUPPORT Filed Jan. 9, 1 951 2 Sheets-Sheet 2 INVENTOR.

HELMUT BRUEQKMANN BY United States Patent 2,705,737 TRANSMISSION LINE SUPPORT Helmut Brueckmann, Little Silver, N. J., assignor to the United States of America as represented by the Secretary of the Army Application January 9, 1951, Serial No. 205,165 2 Claims. (Cl. 17443) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment of any royalty thereon.

e present invention relates to a means for compensating for the ca acity of the insulator by adding an inductance in the circuit.

More particularly, the present invention relates to an operating frequencies, and also to an creased physical strength an age.

In all types of support insulators presently used for en-Wire transmlsslon lines, the construction design is principle of keeping the insulator capacity as small as possible. As a result, the physical strength and the breakdown voltage of these insulators suffer more or less. The described equalization method insulator with in- (1 increased breakdown voltincreased physical It is, therefore, an object of this invention to provide a transmission l1ne insulator.

physical strength with unusually low losses at certain frequencies.

It is a further object of this invention to provide a transmission line of substantially constant impedance throughout its entire length.

e present invention is best to the fol owing specification and the drawings in which each coil is connected to the cap next to it and to the corresponding line wire 25; the other end is connected to the corona shield 12 and the jumper 30. The jumpers should be somewhat loose so that they do not take any part of the heavy strain in the line wires.

The two stand- 8 o No. 200,271, filed December 11, 1950,

2,705,737 Patented Apr. 5, 1955 oif insulators 15 and 16 are supposed to prevent swinging of the jumpers but can be omitted if desired.

e capacities of the caps and corona shields depend on their physical dimensions and the dielectric constant used for the rods. These cathe inductance tical, and would be, for example, 10 turns with a 1 inch diameter core.

With some of the sulators, it is difiicult ofii insulators 15 and 16 on the crossarm and their sepa- It seems ad of the turn angle, this arrangement is not practical for large turn angles. For turn angles exceeding say, 30, the arrangement of Figs. 3 and 4 would be advantageous. In this arrangement, wherein like elements have the same numbers as their counterparts in Figs. 1 and 2, the transmission lines 23, 24, 25 and 26 are connected through coils 33, 34, 35 and line spacing or length was considered unavoidable at any change in direction.

It is also noted, that in this turn arrangement, the jumper wires are held taut in their proper spacing by the compensated insulators 56 and 78, thereby avoiding the ditficulties of supports.

are, of course, compensated by the addition of inductance,

as described earlier. The insulator at points where the line enters into a building. For this insulators 15 and 28 and 30.

The details of a system for compensating for the capacity of an insulator by a decrease in the size of the appropriate jumpers are given in my co-pending application for an improvement in Transmission Line, Serial now abandoned.

Since the difference in insulator capacity in this case would probably be small, the corresponding difference in wire diameter would also be small.

Another way to further standardization is to design the coil for the greatest insulator capacity which occurs in practice, then that part of the coil which is in excess of the optimum value for the particular application can be short-circuited, or the amount of capacity that is needed to equal the capacity for which the coil is designed can be added, for example, by setting a number of connectors on the jumpers.

The physical strength and the breakdown voltage of this insulator arrangement can be made considerably better than that of the presently used insulator systems. It is estimated that the tension in the wires can be at least doubled without increasing the danger of breaking the insulators. This means that the span of the transmission line between adjacent poles (present practice is approximately 90 feet) can be increased by at least 40%, if the same sag of the wires that is presently accepted is permitted. In other words, one pole in about 270 feet of transmission line can be saved in this way. In respect to cost and shipping weight, a comparison could be based on two poles with two of the suggested insulator arrange ments on one hand, and three poles with three of the conventional insulator arrangements on the other hand. It is to be expected that such a comparison would favor the new design. Not only would the line have fewer sources of impedance mismatch, these sources would be effectively compensated.

As a by-product, the suggested insulator arrangement gives a well-defined filter action in the transmission of harmonics of the operating frequency. From this point of view, it is desirable, in long range communications, for example, to have a cutoff frequency of about 30 mes. This corresponds to a lumped capacity of about 17 ,u f. and)an inductance of about 6 hy. (1.5 hy. for each cor While a preferred embodiment of this invention has been described here, other embodiments will be obvious to those skilled in the art.

What is claimed is:

1. At a turn in a transmission line, a first pair of uniformly spaced conductors in a first plane, a second pair of similarly spaced conductors in a second plane substantially parallel to said first plane, and a third pair of similarly spaced jumper conductors in a third plane substantially perpendicular to said other planes, said jumper conductors connecting said first pair of conductors to said second pair of conductors said first and second pairs of conductors meeting said third plane at substantially equal angles, and said third .first and second planes at substantially the same angle, whereby said jumper wires are of equal length and the spacing, length, and characteristic impedance of said transmission line is substantially constant throughout said turn.

2. At a turn in a transmission line, a first pair of uniformly spaced conductors in a first horizontal plane, a second pair of similarly spaced conductors in a second horizontal plane, and a third pair of similarly spaced jumper conductors in a third vertical plane, said jumper conductors connecting said first pair of conductors to said second pair of conductors said first and second'pairs of conductors meeting said third plane at substantially equal angles, and said third pair of conductors meeting said first and second planes at substantially the same angle, whereby said jumper wires are of equal length and the spacing, length, and characteristic impedance of said transmission line is substantially constant throughout said turn.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,473 Rick Feb. 19, 1935 Re. 22,374 Carter Sept. 14, 1943 1,689,683 Conrad Oct. 30, 1928 1,778,395 Lindenblad Oct. 14, 1930 2,165,087 Alford July 4, 1939 2,267,268 Burrows Dec. 23, 1941 FOREIGN PATENTS 463,104 Canada Mar. 14, 1947 pair of conductors meeting said

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