KR20010032560A - Radiating cable - Google Patents

Abstract

The radiation cable includes N first and N second insulated conductor cables that are twisted together in the retaining sheath. At the first end the first wire is connected to the outer conductor of the coaxial feed cable and the second wire is connected to the inner conductor of the coaxial cable.

The second ends of the first and second wires are each connected to a terminal to which the rods are coupled. The radiation cable is less expensive than slotted coaxial radiation cables of the prior art and can be installed in buildings to operate up to about 3 GHZ.

Description

Yarn Cable {RADIATING CABLE}

Wireless reach in large buildings often requires the installation of dedicated equipment. The reach is ensured by an antenna located inside the building.

The use of radiation cables in corridors is technically advantageous but often expensive. This is because the radiation cable installed in the tunnel is a coaxial cable having a periodic pattern of slots. These are expensive, bulky and rigid and difficult to install.

Japanese Patent Application No. 60038902 discloses a radiation cable comprising two first insulated conductor wires having a first end connected to one of the terminals of the oscillator and a second insulated conductor wire having a first end connected to the other terminal of the oscillator and have.

The first wire and the second wire each consist of two pairs of wires that are twisted independently in the retaining sheath. The pairs have different helical pitches to obtain sufficiently low emission frequencies. The difference between the pitches is obtained by pinching two separate pairs of wires.

It is an object of the present invention to provide a radiation cable for the reach of a building which is more flexible, smaller, less expensive and adapted to operate in the high frequency region up to about 3 GHz than prior art cables for application in tunnels. It is to.

Compared with slotted radial coaxial cable, the implementation of the radial cable of the present invention is particularly sufficiently reduced with respect to attenuation, propagation speed and reflection reduction per unit length.

The invention relates in particular to radiating cables used in the cellular telephone area or in wireless local area networks for data transmission in the band 1 to 3 GHz.

1 is a perspective view of a spinning cable according to the invention connected to a cable head;

2 is a cross-sectional view of the radiation cable according to the present invention.

3 is a perspective view of a state transitioned to a conductor wire parallel to the axis of a cable according to a second embodiment of the invention, which transitions between a front wire spiral and a backing wire spiral in one variant of the second embodiment of the invention.

4 is a cross-sectional view of a cable according to the present invention having a dielectric tape.

5 is a perspective view of one end of a cable according to the invention with a metal tape having a non-contact curved surface and a dielectric tape.

* Code Description

CX: Coaxial Cable CR: Radiation Cable

G: Retaining Sheath CF: Conductor Core

F1, F2, F3, F4: Wire GF: Insulation Sheath

PH: pitch CF: outer conductor

TC: Cable Head CN: Connector

RM: Tape XX: Axis

Thus, a second insulated conductor wire having a first end connected together with a first insulated conductor wire having a first end connected together, the number of first wires such as the number of second wires and a first and second wire A high frequency radiation cable comprising an outer retaining sheath,

The first and second wires are twisted together around the longitudinal axis of the cable and around the second end of the first insulated conductor wire, and the second end of the second insulated conductor wire is a terminal or amplifying means of a rod substantially equal to the characteristic impedance of the cable. It is characterized in that each connected to one of the input terminals.

Thus, the cable of the present invention comprises four or more even wires. For example, the cable comprises a quad of conductor wires that are substantially symmetrical and in pair contact with the longitudinal axis of the cable.

Another variant of the radiating cable of the present invention has a cross section having three first wires on one side of the longitudinal diameter plane of the cable and three second wires on the other side of the diameter plane or contacting two second wires and having a first wire in between And six insulated conductor wires equally spaced circumferentially in contact with the two first wires along the circle and with the second wire in opposition therebetween.

The efficiency of the cable is that the first and second conductor wires are connected to a load whose impedance is substantially equal to the characteristic impedance of the cable or to a load whose output is connected to an input terminal of an amplifying means which can be connected to another radiating cable or antenna. By connecting the second end of the cable is improved compared to the cable disclosed in Japanese Patent Application No. 60038902.

The wires are thus twisted together in an outer retaining sheath, in which all wires have the same helical pitch. Compared with the cable disclosed in Japanese Patent Application No. 60038902, the cable according to the invention having two first wires and two second wires has a constant characteristic impedance along the cable, which is more flexible and most importantly, easy to manufacture and therefore It's low cost.

The wires are twisted together at the same time as the retaining sheath or sheathing set comprising the retaining sheath is applied in a single continuous operation.

Indeed, the first end of the first insulated derivative wire and the first end of the second insulated derivative wire are each coaxial to form a connection between the radiating cable and a fixed transceiver station, for example a base transceiver station of a cellular mobile radio telephone network. It is connected to the outer and inner conductors of the supply cable.

The connection may be made identical by means of a twisted pair of supply cables or may be directly connected to the transceiver system to which the radiating cable is fixed.

The first end of the insulated conductor wire pair of the cable and the first end of the other pair of insulated conductor wire of the radiating cable are respectively connected to two conductors of the supply cable or two terminals of the fixed transceiver system.

Although all conductor wires are twisted at the same time as shown below, the present invention actually uses the deleterious effects of radiation from conventional cables having two pairs of wires where crosstalk occurs and emphasizes the effects mainly due to the unbalance of the wire pairs. do.

In order to enlarge the radiation from the cable and the unbalance of the wire pair, the twisted wire sometimes forms a series of forward spirals and sometimes a series of retrograde spirals. The direction of the helix varies, for example, every 8-12 helix pitches.

Preferably, the wire twist section with forward helix is separated from the twist section with backing helix by a cable section in which the wire is substantially parallel to the axis of the cable.

For example, the first conductor wire is staggered with the second conductor wire around the longitudinal axis of the cable or the set of first conductor wire is substantially symmetrical to the set of second conductor wire about the longitudinal axis of the cable.

The spiral pitch of the twisted wire is from about 10 to 50 times the outer diameter of the insulated conductor wire.

More generally, radiation can be increased by causing an imbalance between the other elements of the cable. The imbalance can be caused by the volume difference of the various conductor wires or the capacity difference per unit length between the various conductor wires.

The difference in capacity per unit length can occur by using an insulating material having a different dielectric constant from the different thickness of the insulating sheath of the insulated conductor wire or in the insulation of the insulated conductor wire.

More generally, the one or more first conductor wires and the one or more second conductor wires may differ from each other in at least one of three parameters: the diameter of the conductor core of the wire, the thickness of the insulation sheath of the wire and the dielectric constant of the insulation sheath. .

According to another embodiment, the insulated conductor wire may have a conductor core in a cylindrical dielectric sheath.

The attenuation per unit length of the cable radiating at high frequencies is very strongly affected by the resistive losses in the conductors. At certain frequencies, where cables are used from 1 MHz to 3 GHZ, the current actually flows exclusively on the surface of the conductor.

In order to limit the resistive loss, the electrical conductivity around the conductor should be as high as possible and the perimeter of the cross section of the conductor should be as large as possible. Thus, in the radiating cable of the present invention, each insulated conductor wire may comprise an electrically dielectric core covering around the central portion and consisting of the central portion and the coating is made of a conductive material having a higher electrical conductivity than the central portion.

The first conductor material may be aluminum or an aluminum alloy with high density alumina and the second conductor material may be copper, silver or copper, silver alloy with high density copper or silver.

The dielectric tape may surround the set of insulated conductor wires and may be surrounded by the outer retaining sheath to prevent the sheath of the insulated conductor wire and the outer retaining sheath from adhering to each other. The dielectric tape may further be made of a refractory material: for example, the dielectric tape may be glass silk or mica mineral tape.

Metal tapes having non-contact curved surfaces or one or more metal wires may spirally wrap around the insulated conductor wires between the dielectric tape and an external retaining enclosure that helps maintain a constant characteristic impedance along the cable.

The outer retaining sheath may be polyethylene, polyvinyl, crawlide, elastomer or halogen-free fire retardant according to the environmental properties requiring the cable.

Other features and advantages of the present invention will be apparent from some preferred embodiments of the invention described below with reference to the drawings.

The radiation cable CR according to FIGS. 1 and 2 comprises four identical insulated conductor wires F1 to F4 forming a twisted star quad.

Each wire has a twisted or solid conductor core (CF) made of thin conductor wires to improve the flexibility of the cable; for example, the conductor core is made of heat-cooled copper. And the individual insulating sheaths GF insulate the conductor core from the conductor cores in the other three wires.

In a preferred embodiment, the core of each insulated conductor has a central portion having a diameter of less than 1 mm made of aluminum or an aluminum alloy having a low density of other material and has a low density other material that increases electrical conductivity around the core of the conductor. The branches have a covering around the core with a thickness of several tens of micrometers of copper or silver or copper, silver alloy, thus reducing losses in the cable.

The insulating sheath GF is made of, for example, a solid, cellular or two layer material of polyethylene, polypropylene, polyvinyl crude, silicone or fluorinated material.

The outer retaining sheath G surrounds the insulated conductor wires F1-F4 and fixes them together so that they are not included in the retaining sheath G.

The retaining sheath G is made of thin, crosslinked or non-crosslinked thermoplastic material or elastomer and can be transparent so that different colors of the individual sheaths GF of the conductor wires F1 to F4 can be seen.

In the tubular retaining sheath G, the wires F1 to F4 are twisted about the longitudinal axis of the cable substantially regularly so that the wires F1 to F4 are at the corners of the square when viewed in cross section. In the illustrated embodiment, the wires F1 to F4 increase in the order of 1 to 4 in the clockwise direction such that the first wires F1 and F3 are diagonally opposite each other and the second wires F2 and F4 are diagonally opposite each other. Numbered to

More generally the cable with the above characteristics is twisted with a predetermined spiral pitch PH and simultaneously covered with a retaining sheath G and N first wire and N which are regularly distributed in the circumferential direction around the longitudinal axis XX of the cable when viewed in cross section. And a second wire, each first wire in longitudinal contact with two second wires, with N being an integer greater than or equal to two.

In the embodiment shown in FIG. 1, the first ends E11, E13 of the first wire of the radiation cable CR, such as the diagonally opposed wires F1, F3 constituting the pair of first wires, are With the other two diagonally opposed wires F2, F4, which have a conductor core CF connected together and to the first end of the tubular outer conductor CI of the coaxial cable CX, constituting two pairs of wires. The first ends E12 and E14 of the second wire of the same radiating cable CR have a conductor CF connected together and the first end d of the inner conductor CI of the coaxial cable.

The two sets of two-to-one connections consist of a first connector CN1 that minimizes the impedance mismatch between the radiating cable CR and the coaxial cable CX.

The other end of the coaxial cable (CX) emits a downlink radio signal from the one or more base transceiver stations contained in the cable head via the radiation cable (CR) to the mobile radio telephone terminal and through the radiation cable (CR) the mobile terminal. A cable head TC to receive the uplink radio signal from the base transceiver station.

For example, one or more coaxial cables (CX) are connected to the first end of the quad-shaped radiating cable (CR) installed in the ceiling of the central corridor of the floor of the office building and extend from the roof of the building to the second end according to the invention. It is fixed to the vertical duct of the building. Here are three base transceiver stations for the following kinds of cellular mobile telephone networks:

Depending on access ports for transceivers for emergency and radio paging services at frequencies below 470 MHz, or for wireless local area networks for data transmitted in the 2.4 GHz-2.4835 GH band

FRANCE TELECOM / GSM for the 890-947.5 MHz band, SFR / GSM for the 902.5-960MHZ band and BOUYGUES TELECOM / DCS for the 710MHZ-880MHz band.

The second ends E21 and E23 of the first wires F1 and F3 of the radiation cable CR have a conductor CF connected to each other and to the first terminal B1 of the rod CH and the second wire F2. The second ends E22 and E24 of F4 have a conductor CF connected to each other and to the second terminal B2 of the rod CH in the second connector CN2.

Compared with prior art coaxial cables, the outer and inner conductors of the prior art cables are replaced with two twisted quad wires in the radial cable CR according to the invention.

In a preferred embodiment, the first and second pairs of wires F1-F3, F2-F4 connected to each other at their first and second ends are wires F1-F2 and F3-F4, or F1-F4 and F2-F3. Is replaced with another first and second pair of; When viewed in cross section, each pair of wires is at a square side end at the corner where insulated conductor wires F1 to F4 are disposed in FIG. 2.

More generally, when viewed in cross section, cables with 2N wires twisted together and N In a cable of two, the N first wire is disposed at the corner of the regular polygon having the diameter of the cable having 2N corner at one side and the N second wire is disposed at the corner of the polygon at the other side of the cable diameter.

Similar to phantom circuits for star quads that have not been used in telephones for decades, the capacitance per unit length of the radiating cable (CR) of the invention is derived from the C _pair of conductor wire pairs.

C _CR = 2.5 C _pair

Unit length L Inductance per _CR of the radiating cable (CR) is equal to the two pairs of parallel conductor unit length L Inductance per _pair of a wire connected.

L _CR = L _pair / 2

From the following equation for the characteristic impedance Z _CR of the radiating cable at high frequencies:

Z _CR = _CR L / C _CR is the characteristic impedance of the radiating cable (CR) and a wire pair _CR Z and Z _pair

Induce the relationship between:

Z _CR = Z _pair /2.2

Thus, although the polyethylene sheath (GF) and 110 have a diameter equal to about twice the diameter of the conductor core (CF). Although it is possible to make radiant cables consisting of twisted pairs of usually insulated conductor wires with a characteristic impedance of 50 A polyethylene pair having a characteristic impedance of can be designed.

50 The wire pair of can be obtained with PVC insulation or other materials with relatively high dielectric constants, for example 4-5, but this can impair other transmission properties such as attenuation or propagation speed.

Therefore, the radiation cable (CR) of the present invention is 110 Characteristic impedance pairs 110/2 = 50 Convert to a characteristic impedance pair of.

The load (CH) is therefore Z _CR = 50 Same as

Unit length of the radiation cable Per attenuation is:

= R / 2 Z _CR .

Where R is the resistance per unit length of the radiation cable and R / 4 is therefore the resistance of each conductor wire F1 to F4. Unit length with constant characteristic impedance Sugar attenuation is selected as a function of the diameter of the conductor CF of the wire and decreases as the conductor diameter increases.

The diameter of the individual sheath (GF) and the diameter of the conductor core (CF) are 50 It is chosen to achieve a radiating cable having a characteristic impedance of and an appropriate attenuation per unit length.

The pairs of wires must be very "balanced", ie symmetrical, to facilitate radiation from the cable. For a conductor core (CF) diameter of 1 to 2 mm and insulated conductor wires (F1 to F4), therefore, the pitch of the cable, ie the spiral pitch (PH) of the wire, is substantially equal to twice that value, i.e. 1.5 to 4 mm. In order to preserve the flexibility of the radiating cable (CR) without overloading the wire, it has a diameter of about 10 to 50 times the sheath (GF).

In a preferred embodiment, the radiating cable CR comprises a twisted quad having a spiral pitch PH of about 50 mm or about 2000 pitch at a maximum cable length of about 100 m.

Each of the four wires F1 to F4 has a solid heat cooled copper conductor core (CF) of 1.5 mm and a 2.8 mm outer diameter solid or cellular polyethylene insulating sheath (GF). The outer retaining sheath G is made of halogen-free fire retardant and limits the outer diameter of the cable to 9.5 mm.

50 For cable (CR) characteristic impedance, the attenuation per unit length of the cable is 8.5 u / 100 m at 150 MHz, 15 u / 100 m at 450 MHz, 21 u / 100 m at 900 MHz, and 30 u / 100 m at 1800 MHz. Connection losses from 150 MHz to 1800 MHz range from 70 to 80 euros.

In particular, the maximum cable length is about 80 m for frequencies up to 2 GHz and 120 m for frequencies up to 1 GHz.

The flexibility of the cable is improved by replacing each solid conductor core (CF) with a twisted core of, for example, 7 or 19 fine strands with fine copper conductor wires.

The following two contrasting phenomena should be considered as looking to optimize the radiation cable.

The radiation increases as the symmetry imbalance of the wires F1 to F4 in the cable increases.

Impedance mismatch can no longer be accepted for signal transmission as cable unbalance increases.

In a second embodiment, the radiation is increased without excessive panning transmission by introducing periodic imbalances in the distribution of the four wires of the cable CR. The resulting impedance mismatch is not divided throughout the spectrum but concentrated in one place at a particular frequency and its harmonics. In practice the frequencies are forbidden frequencies and are chosen to be outside the useful radio telephone band.

In the second embodiment shown in Fig. 3, the cable CRa having the same volume and material properties as the cable CR of the first embodiment has a cable CR for the twisted pitch every 500 mm, that is, 50 mm. The cable has 10 forward spirals in series with the full length L and 10 reverse spirals in series with the full length L.

Reversing the twist direction causes impedance mismatches at frequencies of 400 MHz and multiples of 400 MHz, 800 MHz, 1200 MHz, 1600 MHz, and 2000 MHz. The frequencies can be predicted.

In a variant of the second embodiment shown in FIG. 3, the spiral winding of the insulated conductor wires F1 to F4 does not immediately reverse from the forward spiral to the reverse spiral or vice versa, but the conductor wires F1 to F4 are connected to the axis of the cable. Through a cable section of length LP substantially parallel to XX). The length LP may be equal to the pitch PH of the spiral of the wires F1 to F4.

In another variation, the imbalance of the cable is caused by the sheath volume difference or the sheath dielectric constant difference, for example between the four conductors CF of wires F1 to F4 or between the pairs of wires F1-F3 and (F2-F4). Stands out among the conductors.

More generally, the insulation sheathing (GF) of two or more 2N = 4 wires differs in at least one aspect of the following parameters: the diameter of the conductor core (CF) of the wire, the thickness of the insulation sheathing (GF) of the wire, the insulation sheathing. Dielectric constant of (GF) and material or design of conductor core (CF).

In another variation of the first and second embodiments, the dielectric separator tape RD shown in FIG. 4 surrounds 2N = 4 insulated conductor wires F1 to F4 and in turn is surrounded by an external retaining sheath G. .

The tape protects the sheath GF of the wires F1 to F4 from heat while the protrusion of the sheath sheath G prevents the wire sheath GF and the outer sheath sheath from sticking together.

The tape RD is made of, for example, polyester, polypropylene or kraft paper. The dielectric tape RD may also be made of a material that improves the fire protection of the cable, for example glass silk or mica mineral tape.

In FIG. 5, as shown, the metal tape RM is spirally wound around a set of 2N = 4 insulated conductor wires F1 to F4 and lies on top of the dielectric tape RD and underneath the outer holding sheath G. FIG. It is desirable to lose.

The tape RM is wound on a non-contact surface indicating that two helical faces of the metal tape or some metal tapes are separated by, for example, a spiral gap whose width is substantially equal to or double the width of the metal tape. .

In another variation, the metal tape having a non-contact surface may leave gaps as one or more metal wires or radiated electromagnetic fields having a non-contact surface may pass around the 2N = 4 insulated conductor wires (F1 to F4). Replaced with dielectric tape RD having any other metal shield union opening.

In order to economically achieve flexibility in the invention, the twisting of the 2N insulated conductor wires, the application of the tape RD or RM and the application of the projections of the retaining sheath G are carried out in a single operation.

Claims (14)

The first insulated conductor wire having first ends connected to each other and the second insulated conductor wire having first ends connected to each other and the number of the first wires are equal to the number of the second wires and the outer retaining sheath is the first and the first. A high frequency radiating cable comprising two wires, wherein the first and second wires are twisted together about a longitudinal axis of the cable and the second end of the first insulated conductor wire and the second end of the second insulated conductor wire are A radiating cable, characterized in that it is connected to one of the input terminals of the amplifier means or a terminal of the same load as the characteristic impedance of the amplifier. The method of claim 1, wherein the first end of the first insulated conductor wire and the first end of the second insulated conductor wire are respectively connected to one of two conductors of a supplier cable or two terminals of a fixed transceiver system. Radiating cable. The radiation cable of claim 1, wherein the twisting of the wire is a continuation of a forward spiral or a continuation of a reverse spiral. 4. The spinning cable of claim 3, wherein the wire twist section having a forward helix is separated from the wire twist section having a reverse helix by a cable section parallel to the axis of the cable. The radiation cable of claim 1, wherein the first conductor wire intersects the second conductor wire around a longitudinal axis of the cable. 2. The radiation cable of claim 1, wherein the set of first conductor wires is symmetric to the set of second conductor wires around the length of the cable. 2. The radiating cable of claim 1, wherein the twisted wires have a spiral pitch that is between about 10 and 50 times the outer diameter of the insulated conductor wire. 2. The method of claim 1, wherein one or more of the first conductor wires and one or more of the second conductor wires are of three parameters: the diameter of the conductor core of the wires, the thickness of the insulating sheath of the wires and the dielectric constant of the insulating sheath. Radiating cable, characterized in that different from one or more sides. The radiation cable of claim 1, wherein the insulated conductor wires have a conductor core in a cylindrical dielectric sheath. 2. The method of claim 1, wherein each of the first and second insulated conductor wires comprises an electrical conductor core covering the periphery and consisting of a central portion and wherein the coating is made of a conductive material having a greater electrical conductivity than the central portion. A radiation cable characterized by the above-mentioned. 2. The radiating cable of claim 1, comprising a dielectric tape surrounding the set of insulated conductor wires and wrapped by the outer retaining sheath. 10. The spinning cable of claim 1, comprising a metallic tape having a non-contact surface helically wound around the set of four insulated conductor wires. 12. A spinning cable according to claim 11, characterized by a metallic tape having a non-contact surface spirally wound around the set of four insulated dielectric wires and extending between the dielectric tape and the outer retaining sheath. 13. The spinning cable of claim 12 wherein said metal tape having a non-contact surface is replaced by one or several metal wires or perforated metal shields.