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I'm trying to understand how someone can ground an RF signal (especially relating to microstrip lines). I think I'm missing something... Since the impedance of ground is supposed to be \$0\Omega\$, wouldn't all frequencies reflect off it? I suppose when they reflect off it, that means that the voltage at that spot has to be \$0\$V, which I guess implies an impedance of \$0\Omega\$. (\$Z=\frac{V}{I}=\frac{0}{I}=0\Omega\$) Is this how it works?

Thanks.

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I think more context is needed here. If you are trying to kill an RF signal, the best way to do it is with a 50 Ohm resistor (provided your transmission line is 50 Ohms). Connecting an RF line to ground would do exactly what you described (it would reflect everything).

The term "RF ground" found in datasheets is usually used to distinguish between a DC ground. A pad connected to a ground plane with a very thin (high inductance) and long line is a decent ground as long as the DC resistance is low enough. For RF, this ground would be terrible since at high frequencies, inductance becomes the dominant part of the impedance. So, this is the reason why you have so many grounding vias on RF boards

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