[TowerTalk] Hair Pin feed - ???

L. B. Cebik cebik@utkux.utcc.utk.edu
Sat, 4 Jul 1998 21:42:38 -0400 (EDT)


Robert,

For hairpin calculations, see the WA1SPJ program in the HAMCALC
collection--set up from an article in a past issue of Communications
Quarterly.

The hairpin is a shorted section of parallel feedline--hence its inductive
reactance is a function of the wire diameter vs. the spacing--vs. the
length in fractions of a wl--or electrical degrees.

To do the calculation, you need to know the feedpoint impedance without
the hairpin.  It should show significant capacitive reactance in series
with the resistance.  It is the capacitive reactance which, with the shunt
inductive reactance of the hairpin, forms an L circuit to transform an
impedance below 50-ohms up to 50 ohms.

Hope this gets you atrted.

-73-

LB, W4RNL



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