CS247311B1

CS247311B1 - High frequency cable with composite insulation

Info

Publication number: CS247311B1
Application number: CS893984A
Authority: CS
Inventors: Otto Verbich; Pavol Kollarik; Dusan Synak; Vojtech Desat; Maros Cernuska
Original assignee: Otto Verbich; Pavol Kollarik; Dusan Synak; Vojtech Desat; Maros Cernuska
Priority date: 1984-11-22
Filing date: 1984-11-22
Publication date: 1986-12-18

Abstract

Riešenie zdokonaluje konštrukciu vysokofrekvenčných koaxiálnych káblov. Cielom riešenia je zlepšit elektrické přenosné vlastnosti, najma relatívnu permitivitu a tým aj měrné tlmenie tak, aby tieto káble boli použitelné pre přenos signálu v pásme od 1 do 2 000 MHz a výhodné i pre digitálně přenosy. Podstata riešenia spočívá v tom, že zložená izolácia koaxiálneho kábla pozostáva z vrstvy baiónikovej izolácie, na ktorú je tesne vytvořená súosová izolačná vrstva z penovej izolácie, ktorá má vnútornú plochu negativnu k povrchu tvarovanej baiónikovej izolácie tak, že svojim objmom vypíňa konkávne dutiny a deformácie súosovosti vonkajšieho povrchu baiónikovej izolácie. Docielené elektrické vlastnosti v permitivite a zníženom mernom tlmení predurčujú použitie kábla podlá riešenia na přenos digitálneho signálu v počítačových sieťach.The solution improves the design of high-frequency coaxial cables. The aim of the solution is to improve the electrical transmission properties, in particular the relative permittivity and thus the specific attenuation, so that these cables are usable for signal transmission in the band from 1 to 2,000 MHz and are also advantageous for digital transmissions. The essence of the solution lies in the fact that the composite insulation of the coaxial cable consists of a layer of baionic insulation, on which a coaxial insulating layer of foam insulation is tightly formed, which has an inner surface negative to the surface of the shaped baionic insulation so that its volume compensates for concave cavities and deformations of the coaxiality of the outer surface of the baionic insulation. The achieved electrical properties in permittivity and reduced specific attenuation predetermine the use of the cable according to the solution for digital signal transmission in computer networks.

Description

247311

BACKGROUND OF THE INVENTION The invention relates to an improvement in the construction of cables in which the inner core is insulated with balloon insulation. The aim of the solution is to improve the electrical transmission properties, in particular the relative permittivity εΓ and the specific damping, and so that these cables can be used for signal transmission in the 1 to 2,000 MHz band and also advantageous for digital transmissions.

The application of balloon insulation in the production of coaxial cables is one of the most technically demanding, but also the most productive, methods of producing coaxial cables. The structural cables make it possible to achieve the advantageous transfer properties in the event that the inner insulation is not deformed to accept the production because of the failure of the balloon insulation technology. A further problem in the manufacture of these cables is that the balloon insulation does not allow for the immediate application of known manufacturing processes for the formation of outer cores, such as braid wrapping, tape wrapping, foil wrapping, and the like.

A solution (AO 208 600) is known, whereby the present invention is solved in that an insulating layer in a molded tube is layered on the balloon insulation.

Such a solution for the construction of RF coaxial cables known as the so-called tube-balloon insulation allows for the partial removal of technological deficiencies such as changes in the balloon insulation profile, sealing of the insulating layers, etc. This tubular-balloon insulation has an effective compensating, buffering and protective function by applying self-minimizing wave impedance deviations, unwanted electromagnetic wave scattering, diffraction, abson- sion and interference. At the same time, however, the formation of an insulating tube at the top of the balloon insulation signifi- cantly worsens the relative permittivity of the cable insulation and hence the increase in specific damping w. The tubular insulating layer formed does not provide for the achievement of cylindrical, ie uniform coaxiality, of the insulating layer of the cable. The existing misalignment of balloon isolation merely mitigates. However, the technique of forming a tube on a balloon insulation is very demanding in terms of both technology and production.

The above-mentioned drawbacks are solved by a solution which consists in that the concentric foam layer of the foam polymer discharges the concave cavities and the alignment of the outer surface of the outer surface of the aluminum insulation. The advantage of the proposed solution of the construction of a high-frequency cable with balloon insulation is that the foamed polymer layer adjusts the balloon insulation structure and allows to achieve a uniform cylindrical, tapered shape of the insulating layer and thus to achieve the coaxiality of the entire coaxial cable. Such a uniform tolerance of RF cables is achieved so that they meet the conditions of minimum inhomogeneity of the cable diameter above the insulation, which are comparable to pure foam coaxial flaps. For example, for a diameter above the insulation Di = 9.6 ± 0.2 mm. The technology of applying a coaxial insulating layer of foamed polymer is essential to simplify the tube forming technology above the bubble insulation. In doing so, the concave cavities are filled completely in the area of the balloon insulation neck, but only to form a foam surface layer above the balloon insulation in the places of its ovality - a violation of its cohesion. In these places the foam insulation layer is on the entire surface of the insulation and the balloons will be "submerged" there. This results in a reduction of the relative permittivity value and thus also of the damping of the pipe against the tubular-balloon insulation. The comparison of the measured parameters is as follows:

Insulation Type £ Ra (60 MHz Balloon 1.12 82% Tubular-Balloon 1.28 100% Balloon with Foam 1.18 94%

PV layer

The improvement of the insulation properties of RF coaxial cables by the solution of the invention makes it possible to reduce the transverse dimensional cables. This effect is manifested by a reduction in the material cost of production, for example, in the production of a secondary network, a cable distribution (TKR) would mean that, with a prescribed damping of a = 6 dB / 100 m at 200MHz, on an existing medium coaxial pair (SKP) of 2.6 / 9.6 mm, it saves about 150 kg of electrode medium per km of cable. An important advantage of the present invention is the increase in mechanical strength of the RF cables at the points of the colonic insulation. Achieving a lower value of relative permittivity ε ,. against tube-balloon insulation means reducing the digital distortion of the digital signal attributed to the coaxial cable. In the field of use, this means that the coaxial cable of the invention can be used to transmit digital signals in computer networks, especially for connection to terminals.

The accompanying drawings schematically show a coaxial composite composite cable according to the invention. Fig. 1 shows a continuous layer of foamed insulation and Fig. 2 is an embodiment where only the concave hollows of the balloon insulation are filled. The conductive inner core 1 is an insulated balloon insulation 2 on which the second insulating layer 3 of the foamed polymer is tightly sealed, in our case high pressure polyethylene (PE). On

Claims

247311 of the top of this foam insulating layer 3 is formed by a known outer conductor core 4, for example by braiding and outer insulating sheath 5 of a high frequency coaxial cable. In the following three examples, specific modifications to the invention are disclosed. EXAMPLE 1 A coaxial cable having a wavelength of 75 ohms according to the present invention has a polyethylene balloon insulation 2 having an outside diameter of 11.5 millimeters on the copper core 1, the cores of which are filled with a foamed insulating layer 3 of polyethylene. The outer core 4 is formed by a known method - braid braid braid. The outer insulating sheath S is made of stabile stabilized PVC. The characteristic values experimentally obtained on the sample set were as follows: 75 ± 0.5 ohm wavelength at 200 MHz. Impedance uniformity expressed by the attenuation attenuation of the band up to 1000 MHz «i 40 dB, relative permittivity εΓ = 1,188, shape factor of the transmitted digital signal <0,2, specific damping size 0.0558 dB / m. Example

The coaxial cable with a 50 ohm wavelength has a polyethylene balloon insulation 2, the outer diameter of which is 7.25 mm, wherein the foam insulating layer 3 fills the balloon insulation tubes in such a way that it forms a cylindrical composite insulation. The outer core 4 is formed by a copper foil backing with overlapping and 12-angled undulating long-tight drums. The sheath 5 is made of a dummy-stabilized PVC. The characteristic values obtained on the sample set were as follows: wave impedance 50 ± 0.3 ohmpri 200 MHz, specific damping of 0.0929 dB / m, wave impedance uniformity expressed by damping in the band of up to 1,000 MHz κ 40 dB and 1 to 2,000 MHz, 36 dB, coefficient of distortion-transmitted digital signal <0.3. Example

3 A coaxial cable with a 75 ohm wavelength has a polyethylene balloon insulation 2 with an external diameter of 12.3 mm, whereby a continuous foamed polyethylene foam insulation layer 3 expelling cavity-balloon insulation 2 with a diameter above the insulation of 17.3 mm is embossed. The outer core 4 is made of a copper-lined copper strip overlapping the outer insulation ducts, the sheath 5 being of stabilized polyethylene. The characteristic values obtained are as follows: 75 + 0.2 ohm wavelength impedance, impedance uniformity expressed as damping ž 40 dB, relative permittivity εΓ = 1.315, specific damping size 0.0431dB / m at 200 MHz, shape distortion factor at digital signal transfer <0.15. SUBJECT A high-frequency cable with a composite insulation consisting of two superimposed layers, namely a balloon insulation layer and a saose insulating layer of foamed polymer, characterized in that the invention is a coaxial insulating layer (3j of foam polymer) with its volume it turns concavities and deformations of the alignment of the outer surface of the balloon insulation (1 sheet of drawings1