RE: [SI-LIST] : Trace Impedance Selection

About this list Date view Thread view Subject view Author view

From: Mary (mary@advocate.net)
Date: Fri May 05 2000 - 14:13:36 PDT


Somone recently claimed that higher impedance transmission lines
radiate more because their impedance is closer to the 377-ohm
impedance of free space. This is not true. It is not possible
to judge anything about the radiation from a transmission line
based on the value of its characteristic impedance.

Characteristic impedance is the ratio of voltage to current in a
forward traveling wave. The ratio of electric to magnetic field
strength in a free-space transmission line is approximately
377 ohms regardless of what the characteristic impedance is.
Even if you were to build a transmission line with a 377-ohm
characteristic impedance, there is no reason to believe it would
radiate any better or worse than a 300-ohm or a 400-ohm line.

Mary

**** To unsubscribe from si-list or si-list-digest: send e-mail to
majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu
****


About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Wed Nov 22 2000 - 10:50:12 PST