On Jul 4, 5:29 pm, rick frazier wrote:
Not sure where you get the swr repetitive over a band of frequencies
stuff, (perhaps I don't read enough of the group messages) but to reply
relative to dummy loads in general....

This comes from the radiator listed on my page
unwinantennas.com/



Yep, Dummy Loads do radiate, they just don't radiate very well. In

very true
fact, most of them are encased in a metal enclosure of some sort to
provide two major functions, reducing the radiation, and to provide oil
or other medium for cooling.

On the other hand, your statement/question concerning whether anything
that conducts also radiates, the answer is "yes" so long as it isn't

In a very general sense this is true because most if not all materials
at room temperature
have resistivity which is a measure of radiation. But there are some
materials that lose their resistivity
at extremely low temperatures of which the best known is a super
conductor


shielded by something else, the skin effect helps provide that shielding
(coax, with fields on the center conductor and the inside of the shield)
or in a configuration that cancels the radiation with an equal and
opposite radiation (twisted pairs, ladder line).



I have doubts about twisted pairs which is what I use for my
antennas.
The reason for crossed wires for me is to cancel lumped capacitances
and where the reversal of turns cancels imposed loaded inductances
Thus the length of wire used consists of only distributed loads as
required by Maxwells law
with length being N times wavelength. I have seen reference to
canceled radiation in some
antenna books but if I remember correctly the cancelling effect
occurs on near field radiation only.


Relative to carbon
life forms, I've successfully loaded a tree and made (local) contacts,
but the efficiency was probably near zero. Though many items may
conduct and therefore radiate, their efficiency and effectivity as an
antenna can be so low as to be readily compared to transmitting on a
dummy load. Thus it is not unusual to hear ham conversations describing
a given antenna/configuration as a dummy load...

Interesting that you refer to life forms where carbon undergoes
various changes and classifications
as it decays, (c13) in the extreme. Tho I have seen some strata of
earth listed
as a carbon but then elsewhere as a mineral which I find confusing!
Ofcourse a tree consist of molecules
of water which is a diamagnetic material. Thus will have particals
drawn to rest upon it to radiate as well as particles
released by updrafts in a rainstorm allowing the particles to return
back to a suitable place in
quantum form as with lightning
Good posting
Regards
Art KB9MZ

--Rick

Art Unwin wrote:
I am trying to understand why a low swr repetitive over a band of
frequencies is considered by hams to be a dummy load.! This
consistently shows up in statements by the itelligensia of this
newsgroup. Following up on the logic of that idea it would suggest
that if swr was totally constant ( not sure how that could be) then
all radiation must be zero or self cancelling.?
This thus suggests that if a log periodic antenna was unlimitted in
the number of elements used would in the limit drop down to zero
radiation!. So following the thinking of this group the oscillations
that I show on my page

unwinantennas.com/

as a progression towards zero radiation since Q eventually is going to
equal zero.
Is this why the decreasing oscillation is defined as a dummy load on
this newsgroup?
The term comes up so often that I am compelled to look for what I am
missing, especially since carbon
is conductive and thus in the minds of many must therefore be
radiative!
Ofcourse the statement bandied around that if a material is
condunctive then it must radiatiate
could become fact instead of an old wives tales if stated enough
times.
Art