# [SI-LIST] Re: characteristic impedance at DC

*From*: "Beal, Weston" <Weston_Beal@xxxxxxxxxx>*To*: "haaeri@xxxxxxxxx" <haaeri@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>*Date*: Mon, 9 Apr 2012 22:49:59 +0000

Characteristic impedance applies to propagating EM waves, so it does not apply to DC. Or, if you look at the general equation that you cited, you can see that when jw = 0, the impedance approaches the line resistance. Somewhere in college I remember seeing a graph of the general impedance equation compared to actual measurement at low frequency. They are the same above some kHz, but diverge as frequency decreases. Weston -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of mohammad haaeri Sent: Monday, April 09, 2012 3:31 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] characteristic impedance at DC Hi, What is the characteristic impedance of a transmission line at DC? If you are saying Z0=sqrt(Rdc/Gdc) at DC, since Gdc=0, and Rdc is not zero, therefore Z0 is infinite. Is it correct? How does behavior of L, R, G, and C (line parameters) change vs. frequency (at low and DC, and at very high frequency)? Can Z0=sqrt(R+jwl/G+jwc) be used for all frequencies? Thanks, mohammad ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: http://www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: http://www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu

**Follow-Ups**:**[SI-LIST] Re: characteristic impedance at DC***From:*Nick Luther

**References**:**[SI-LIST] characteristic impedance at DC***From:*mohammad haaeri

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