Hi Guy,
> This is a non-issue, Tom.
I think it is a critical issue, because it demonstrates the difference
between EM radiation and induction fields that only store and return energy
to the system.
> It stems from what I meant when I said "cancel fields".
>
> Apparently some considerable number, even the majority, think this
> phrase means cancel fields entirely. To others this means
> cancellation is taking place at some level.
Then the question arises, how much does it reduce fields?
As far as I know, all we can do is redistribute those fields as evenly as
possible over the widest area possible in the lossy media to reduce losses.
> The FCP radiates at -30 dBi according to NEC4. That's really low for
> an antenna element. But, it DOES radiate.
But that has little to do with local losses in the soil.
> According to NEC4, using area integration of field squared data from
> the counterpoises only, excluding the vertical radiator, the FCP only
> has 8.2% of the power loss in the dirt as a pair of 1/4 wave raised
> radials.
What do you think of this example using a lossless half wave dipole antenna
over the same soil:
Dipole with lossless wire:
freespace 100% eff and 72.3 ohm
45 feet 46% eff and 37.6 ohms
10 feet 6% efficiency and 54 ohms
Comparing an FCP dipole:
Freespace 99.2% eff 0.03 ohms
45 feet 20% eff and 0.04 ohms
10 feet 0.4% 1 ohm
Here is my confusion:
The theory (correct me if I misunderstood it) is folding the element
reduces fields in the earth compared to spread-out elements, and
concentrating the field in a small area also reduces earth losses. I
understand the article to say reducing the area exposed to fields reduces
loss.
If that is the case, why is a full-size lossless-conductor dipole's
efficiency higher (earth losses lower) than a dipole made from two right
angle FCP's? Both have equal soils and both are lossless internally, so all
losses are by fields in the earth.
What I understood, and always found true, is spreading fields out over a
larger cross section of lossy media reduced losses. This is because current
and electric field density is less.
Why does a 260 ft wide lossless dipole have less earth loss than a lossless
compact folded antenna at the same height? What am I missing?
73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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