RadioBanter - View Single Post - No antennae radiate all the power fed to them!

Lostgallifreyan · November 1st 14, 06:02 PM posted to rec.radio.amateur.antenna

wrote in :

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

Nope, voltage is applied to an antenna causing currents to be created
which in turn cause an electromagnetic field to be created.

As antennas are made of real materials they have a resistance and the
current through that resistance leads to losses.

However, in the real world most antennas have an impedance in the tens
of Ohms while the resistance is in milliohms, so normally the losses
are trivial compared to the radiation.

I'm glad you're doing this. Rather than get into technicalities I'm not sure
of, I'll just say I'm glad to see a counterpoint that doesn't make me wonder
if Ohm's and Watt's laws mean anythign anymore, and wonder if I'm missing
something I shouldn't when seeign phrases like 'launching a wave' or 'feeding
power', when all I have ever learned has taught me that power is DRAWN ON,
not FORCED INTO.

I'll explain in off-topic manner why I'm glad this is happening... I was
raised listening to Schubert, Chopin, Bach, Lizst, etc, hearing them on a
piano played by a mother who might have been a concert pianist for a living
if she hadn;t feared fame and decised to marry and have kids. Later, having
left home, I began to miss what I had taken for granted. And one day I heard
soem geezer ona radio say that Chopin left hand parts were 'metronomic'. I
was shocked! Had I missed something this scholarly pronouncement was informed
by, something years of actually hearign real performace throughout my entire
childhood had missed?!

The answer, of course, is NO. The guy was like the emperor sounding off about
his new clothes. A Chopin left hand part is not metronomic. It anchors what
the right hand is doing, but it shifts in its own right, delivering the line
like a well spoken phrase. It moves with thwe mass, not against it. Just like
theory moves with discovery, not against it.

It can be easy to get lost in difficult things. Worse yet, ONE repeated,
inane, or insane, pronouncement can produce real doubt. A human brais is
highly fallible! I went to a shop fpor years, saw the same floor day in, day
out. One day they changed it. To this day I do NOT recall that old floor.

I hope this off-topic rant hasn't doen more harm than good, but I felt like I
should do it, to explain in several ways at once why repeated careful
correction of a repeated error is important. It might not change the person
making the error, but it will almost certainly help prevent other people
losing thweior footing on a track they'd thought secure.

Incidentally, I know from my own coding efforts that unlearning bad habits is
usually a greater task than learning new, better ones! Sometimes I tire of
repetition, but a bit more patience is in order. Context is eveything. It
depends what is being repeated.

We're all vulnerable to wanting renewal, and can grab for it when it's not
really there. Real new stuff usually only becomes apparent when all the old
has been explored and found wanting, so when old familiar theory gets
repeated and NOT found wanting, there's some real relief there. New stuff
will be built on it, it won't come by discarding it like it means nothing.

This has been a longwinded, but I hope convincing way of saying that I think
what you're doing is worth doing. Saying less might not have meant nearly as
much.

The basic problem is wider too, the internet at large is full of data, not so
much info, and even less wisdom, which used to be easier to come by than it
is now.