"Yuri Blanarovich" wrote in message
...

Does this antenna have an upper limit on the frequency it'll operate
at?
I'd think some real life data on efficiency could be derived from
enclosing
anantenna in a 'big enough' styrofoam cooler type enclosure. If the
parts
that *I* suspect to be lossy might cause a significant temperature rise
with
several hundred watts fed to the antenna.

Jerry


There is no limit on the operating frequency of any antenna. If you can
feed RF
into it, it will radiate. Question is where, pattern is determined by the
electrical length of the radiator.
The real efficiency of shortened antenna should be indicated by the
comparison
with full size equivalent (or any other known type) and measured field
strength, like it is done in mobile antenna shootouts.
Any RF energy lost in heat is not radiated and will show up in lower
signal
levels. It is important to compare antennas with the same radiation
pattern and
ground system.

Yuri, K3BU.us

Yuri

Youve gotten too refined. I mostly know about basic antenna theory and
modeling. But building a VHF model of a 40 meter antenna with #12 copper
wire wound around a 4 inch mandril might be impractical.
But, if the "wonder antenna" is small enough to be enclosed (mostly) in
something transparent to the RF but not to the thermal thats generated by
any I^2* R losses, wouldnt the temperture rise inside the enclosure give a
decent indication of efficiency?

If this "wonder antenna" designer claims to be able to shape the radiation
pattern with an antenna significantly shorter that a 1/4 wave stub, He
really has something. I suspect that the something he has is mental
illness.

I've been following this info on the RI antenna and have considered it to
be so 'snake oilish' that it would never see the light of an auditorium.

Your post about attending the lecture made me wonder if anyone asked about
*any* simple (approximations) measurements like the styrofoam radome to get
some idea of the I^2*R power lost in the antenna. If he has an antenna, and
a transmitter and enough room to build a foam igloo it seems that alot of
data on efficiency could be obtained.
If I had any interest in describing an antenna I'd built, I'd at least use
an infared thermometer on the section of the antenna suspected as being the
most lossy.

Jerry