Impendance Hole Sizes


  
            Zo=(138 log d1/d2)/     ------------------	     
	     the sq root of "e"      |       
                                     |     |
	 		            d1    ------------
         d1=hole diameter            |    ------------ 
         d2=pin diameter             |     |
         "e"=dialectric constant     |      --d2
	     in air = 1             ------------------

| Zo | | air | teflon | | impedance | log d1/d2 | constant | constant | ----------------------------------------------- ----------------------------------------------- | 5 ohm | .0362 | 1.087 | 1.124 | | 10 ohm | .0725 | 1.182 | 1.268 | | 12 ohm | .0869 | 1.221 | | | 15 ohm | .1085 | 1.282 | 1.422 | | 20 ohm | .1450 | 1.390 | 1.603 | | 30 ohm | .2165 | 1.648 | 2.008 | | 40 ohm | .2800 | 1.950 | 2.570 | | 50 ohm | .3620 | 2.300 | 3.250 | | 60 ohm | .4350 | 2.720 | 4.115 | | 70 ohm | .5060 | 3.215 | 5.210 | | 80 ohm | .5790 | 3.790 | 6.610 | | 90 ohm | .6510 | 4.470 | 8.375 | | 100 ohm | .7250 | 5.304 | 10.600 | **example: Find hole size (in air) for .050 dia pin to maintain 50 ohm impedance.[.050 x 2.300 = .115 dia]