Jan, I don't know what kind of time-domain routines your VNA has, but an excellent source of time-domain information can be found in Agilent application notes and user manuals. Especially check out: http://cp.literature.agilent.com/litweb/pdf/08510-90281.pdf Read Chapter 11, "Introduction to Time-Domain Measurements." Some excerpts: Step Rise Time (10% to 90%) = 0.45/BW * Window Factor Impulse Width (50%) = 0.6/BW * Window Factor The window factor depends on the type and shape of windowing filter(s) you use, and is typically between 1 and 3. Sharp windows tend toward lower numbers, and soft windows tend toward higher numbers. I don't think it says so in the document, but the window referred to is a Kaiser-Bessel window chosen because of its flexibility. - Daniel From: "Jan Vercammen" <jan.vercammen.jv1@xxxxxxxxxxxxxxxx> > > Hello SI-list, > > I have a question about the saptial resolution of vector network analysers > (VNA) > with time-domain TDR option, that is, to resolve discontinuitites in > space (=length dimension) > > Is there a rule of thumb for estimating the spatial resolution of a VNA > with a > TDR time-domain option from knowlegde of its bandwith BW. > > I have found one rule in an application note: 15cm/BW(Ghz). For example, > for a 6GHz > BW the spatial resolution is about 2.5cm for an effective dielectric > (dkeff) of 1.0. > You probably get better resolution for PCB or cable measurments. The rule > of thumb would become: 15cm/(sqrt(dkeff) BW(GHz). > > Another question concerns the relation between the VNA bandwith and the > available > effective rise time of the step or pulse of the time domain signals. I > assume that one > cannot use the rule trise=0.35/Bw because there BW refers to the 3dB > breakpoint > (the effective BW is bigger). A VNA bandwith is its upper limit. > > -1- Is the above spatial resolution rule correct? > -2- Is there a rule of thumb to convert bandwith (BW) into an effective > rise time (10-90%) > of a VNA with a time-domain option? > > > > > Kind regards, > > Jan Vercammen -- Daniel ZZZ-dgun-ZZZ-@xxxxxxxxxxxxxxx (remove the Z-'s to reply--they're what I do when I read spam) -- __________________________________________________________ Sign-up for your own FREE Personalized E-mail at Mail.com http://www.mail.com/?sr=signup ------------------------------------------------------------------ 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 archives are viewable at: http://www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu