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
