| 摘要 |
1,145,524. Printed circuit impedance network. STANDARD TELEPHONES & CABLES Ltd. 11 Nov., 1966, No.50566/66. Heading H1R. A stripline network for simulating a non- loaded paired telephone cable of characteristic impedance Z o is made by first simulating a cable impedance Z m greater than Z o by means of a stripline of length l, and then moving the position of the contacts on the stripline by a distance Kl where K is given by the formula K = 1/2 (1 - Z 0 <SP>2</SP>/Z m <SP>2</SP>). As shown, the invention is applied to a line similar to that described in Specification 1,122,873 and consisting of thin film strips 11, 11A of width b and resistivity Rs deposited upon dielectric layers 10, 10A. The line is wound into a roll together with a conductive shielding strip 14 the edge of which makes contact with a metal coating on one end of the roll. The line has an impedance between its ends Z m = l/b #(2R s /j#C s ), where C s is the specific capacitance between the thin films. In order to simulate an impedance Zo<Zm, the terminals 12, 12a and 13, 13a are moved inwardly by the distance Kl as stated above. The terminals need not be exactly opposite to each other but may be spaced equal and opposite distances from the nominal terminal points. |
