[SI-LIST] FEXT for microstrip line doesnt increase as spacing increase?

From: Shawn Zheng <shawn.h.zheng@xxxxxxxxx>
To: si-list@xxxxxxxxxxxxx
Date: Sun, 20 Sep 2009 13:46:19 +0800

Just found that FEXT doesnt necessarily increases as spacing between two
single ended traces increases.
FEXT coefficient is proportional to Cm/L-Lm/L. As traces are separated
further, both mutual indutance and capacitance decrease. So I think it makes
sense that total FEXT may not necessarily become less.
For 8mil wide microstrip line with 4mil dielectric thickness,  I sweep the
distance between two traces from 10mil to 29mil. By observing s parameter,
10mil>11mil>12mil>13mil>14mil>15mil>16mil>17mil>18mil>19mil>20mil>22mil>21mil>25mil>24mil>23mil>26mil>27mil>29mil>28mil.
25mil spacing has more xtalk than 24mil and 23mil spacings.
Does it seem correct to you?
Shawn


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[SI-LIST] FEXT for microstrip line doesnt increase as spacing increase?

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