75 to 50 ohm

[Alex Fraser]

I want to use some 75 ohm CATV hardline at 2.4 gig (DSSS lan card). A
matching piece of coax is recommended in the ARRL handbook, but not
specifically  at this high of frequency. I understand the square root of
the sum of squares to find the value of the matching section. I was
thinking  a length of 6061 aluminum home made coax made to slip over and
clamp to the CATV hardline on one end and have a flange for an "N"
connector at the other. I can  figure out the dimensions to machine to
get the matching section's impedance in the ballpark, but wonder what
shape the ends should be for low loss and little reflection? Should I
taper the ends to blend the change in diameters or leave the edges
square? Or for that matter should I taper the whole section? If I need
to have a constant taper how could I calculate its dimensions? And
finally am I causing more losses by trying to match than by ignoring the
mismatch and getting on with it?

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~~~~~~~~ Alex Fraser  N3DER ~~~~~~~~~~~
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