[Antennaware] 160 meter 3/8 wire, steel or copper

[OZ1AXG Flam]

Hi Terry

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?

--
OZ1AXG Flam


----- 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.