[Antennaware] 160 meter 3/8 wire, steel or copper
oz1axg.nospam at dxmail.dk
Wed Sep 24 20:28:46 EDT 2008
It would be better to have the antenna at resonans around 1830 (CW portion
of the band), rather than 1860 where it is now , but this is where it endend
up with the fixed capacitors.
So if i change the wire to Copper, it would move even further up in
frequence (+13KHz)... i.e the wrong way!
As I understand your calculation, cap value is with a fixed wirelength...
however what would the calculation in EZNEC yield if I where to change the
antenna wire to 1.5mm Cu wire AND add 75 cm to the length of the antenna
wire making it 47,25 meters?
----- Original Message -----
From: "Terry Conboy" <n6ry at arrl.net>
> I modeled this with EZNEC (without the tower) and assumed the 1.5 mm
> diameter stainless steel wire has a resistivity of 7.2 e-7 ohm-m and
> relative permeability of 1.02. I estimated about 20 ohms of ground
> loss resistance. Here's what happens at 1860 kHz:
> Cu G=-0.43 dBi Z=52.6 -j 46.6 SWRmin=1.13 at 1922 kHz BW=97
> kHz (50 ohm SWR 2:1)
> SS G=-1.48 dBi Z=68 -j 36.2 SWRmin=1.44 at 1907 kHz BW=90 kHz
> The adjacent tower will modify these values depending on where it is
> resonant, cross section, etc.
> With copper, you should get about 1 dB more signal, a better match to
> 50 ohms, and resonance moved up about 15 kHz. Adding another 27 pF
> in parallel (457 pF total) should restore the resonant point.
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