DE102008062744A1 - Electric cable for signal transmission in low or high audio frequency area, has twin conductor with optimized propagation time and length, where distance from two signal conductors is adjusted - Google Patents

Abstract

The electric cable has a twin conductor with optimized propagation time and the length, where distance (d) from two signal conductors is adjusted such that the inductance is measured at one of the two cable ends, where another cable end is closed shortly. The individual inductance of a front and rear conductor of the cable has all the similar values among each other.

Description

In the patent DE 102007023935 is a structural design of a symmetrical electric cable described, with the following feature: The inductance measured at one of the two cable ends, while the other end of the cable is electrically short-circuited, and the inductance of the forward and return conductor, while the terminals of the remaining signal conductor remain open , all are equal to each other. The invention has for its object to realize a double conductor with the feature as a further embodiment of the electric cable with optimized Propagationszeit to Signalübertragun. The object is achieved by the object features specified in the characterizing part of the patent claim.

The construction of the double conductor is in 1 shown. The two signal conductors are designed as two identical round hollow conductors. The cavity in the electrically conductive tubes is either filled with an insulating Aderfüllmasse or consists of an elastic and insulating core, which is surrounded by a copper sheath. As a suitable Aderfüllmasse z. B. silica granules are used. Such signal conductors are then guided parallel to each other at a distance d to the two core centers along the cable. The design of the signal conductor has the advantage that the internal inductance of the wire can be neglected. Compared to a solid metal wire, the magnetic field inside the wires is zero, so that signal density-dependent modulation of the current density across the cross section of the conductor is prevented.

To determine the external inductance L _c (self-inductance) of a free conductor piece with the length l is shown in the figure 2 the magnetic flux Φ _{l1 is} calculated. As the interspersed area, the area is taken, which is spanned by the conductor and the extended to the infinite vertical to the conductor ends. The exact solution to this problem is given in [1].

Starting from the relation l >> r, the approximation for the value L _e may be used. In the case that the two signal conductors are surrounded by air, the permeability of the empty space μ _{0 is} taken for μ.

The partial mutual inductance M _l2 or M _2l (mutual inductance) is shown in the figure 3 calculated. The magnetic flux Φ _l2 = M _2l I _l follows from equation for L _e by the commutation of r with the distance d + r. The closed-loop inductance L _loop can be calculated as follows (the values of M have the sign minus, because the magnetic lines of the flux Φ _{l2 are subtracted} by the gray area): L loop = 2L e - M l1 - M 2l ≈ 4l {ln 2l r - ln 2l d + r } [NH]

Now, for the predefined values, r and l, the sought value for the distance d between the signal conductors can be found. From the condition for an electric cable with optimized propagation time L _loop = L _e follows: L loop = L e ⇒ 2ln d + r r = ln 2l r - 1

literature

• [1] Tim Healy, "The Inductance of a Straight Wire," Santa Clara University, June 1, 2000

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 102007023935 [0001]

Claims (1)

Electric cable for signal transmission in the low (audio) or high frequency range, which is designed as a double conductor with optimized propagation time with the length l, wherein A) the signal conductors are each formed as a round hollow core with the radius r, B) the cavity in the electrically conductive Tube is either filled with an insulating Aderfüllmasse, or consists of an elastic and insulating core, which is surrounded by a metal shell, characterized in that the distance from the two signal conductors d is set so that the inductance measured at one of the two cable ends, while the other end of the cable is electrically short-circuited, and the single inductance of the return conductor of the cable, while the terminals of the remaining signal conductor remain open, all have the same value among each other, or, mathematically speaking, that for the geometry of the double conductor between the quantities d, r and l follow nde relation applies: L loop = L e ⇒ 2ln d + r r = ln 2l r - 1