[Lowfer] 160m vs 1600m

Thu, 28 Mar 2002 22:32:01 -0500

Ed and all,

Let's list what is similar between 160m and 1600m and what is not similar.

Similar:
1. Same formula for resonant frequency
2. Same formula for radiation resistance
3. Same Maxwell equations for E and H field formation
4. Same surface wave 1/d signal falloff (Not accounting for Attenuation 
Factors)

Not similar:
1. Effect of the soil immediately surrounding the antenna
2. Surface wave Attenuation Factors are much less at 1600m. (This is the 
additional signal attenuation with distance that must be added to the 1/d 
signal falloff)
3. Space wave propagation is grossly different
4. Efficiency for a typical backyard-sized antenna is much less at 1600m

It looks like the similarities all have to do with the antenna itself while 
the dissimilarities relate to the environment in which the antenna is 
placed.

Bill A

>From: Ed Phillips <[email protected]>
>Reply-To: [email protected]
>To: [email protected]
>Subject: Re: [Lowfer] Re:helically loaded verticals
>Date: Thu, 28 Mar 2002 17:57:39 -0800
>
> > > wavelength. So what happens at 1600m is not quite the same as on 160m,
> > > because of the difference in scale, so having helical loading, or an
> > > elevated loading coil could be an advantage on LF.
> >
> > I respectfully disagree. Nothing changes. It all works the same
> > when everything is scaled to the same dimensions as a fraction of
> > wavelength. That is why formulas do not change from VLF to VHF
> > and higher, and why modelling programs can use the same engine
> > no matter what frequency we are on.
>
>	You are right on this last point, although the properties of the ground
>may be different.  One of my antenna-designing friends at Hughes - Don
>Bostrom, N6IC - used to build little scale models of beams and stuff and
>test them at UHF, with very usable results.
>
>Ed
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