Hi Andy,
Yes, I agree. It makes sense that that efficiency would be a power in -
power out ratio. I was wondering how to compare it, though. E.g.,
what would be the efficiency of a plain old dipole up 30 feet in my
backyard? If the efficiency for that arrangement were, say, twice that
of a proposed rigid loop as calculated via the KI6GD program, I would
have second thoughts about spending the money to build such a loop (or I
would increase circumference up to 33 % or increase pipe diameter up to
the limit of my wallet.)
As I play with the program, using "reasonable" copper diameters and side
lengths (reasonable to me), I come up with efficiencies in the 25 to 40
% range.
Thanks,
Dave
--- In loopantennas@..., Andy <Andy.groups@...> wrote:
Also, what is the LoopCalc program comparing to when it states that a
certain configuration is , e.g., 51% efficient. Compared to a
standard
dipole?
I think all antenna efficiency programs use a resonant dipole
in free
space as the standard for antenna efficiency.
Actually, as far as efficiency is concerned, the reference is ideal or
no
loss. Efficiency, unlike gain, is not compared to a dipole or anything
else. 100% efficiency just means that all the power you feed into the
antenna, gets turned into radio waves and none is lost in the form of
heat
(resistance losses). 50% means half your input power is lost as heat
and
never gets out.
After dealing with the power lost to heat, then what's left over is
affected
by the antenna's gain ... which IS compared to a reference antenna
(dipole
or isotropic), and is a function of direction (since antenna gain is
all
about concentrating signals in some directions while sacrificing signal
in
other directions).
Andy
