"John Smith" wrote in message
...
Jerry Martes wrote:
Hi Denny

The fact is, I probably get "ruffled" too easily, probably because I'm
insecure. I'm not the sharpest antenna designer around.
My way of antenna design relies mainly on actual, measured data, so I
am a little short on convincing theoretical data. But, my approach to
determining relative efficiency would be based on measured data.
If *I* had made any statement on the efficiency of *any* antenna, you
can be sure I would include some measured data. Measuring Yagi antenna
loss is probably too mundane for Art. He already knows things that would
require me months of testing to 'check up on'.
If I wanted to know the "I squared R loss" efficiency of one antenna
compared to another antenna, I'd need to conduct time consuming
experiments.

Jerry






"Denny" wrote in message
s.com...
Jerry, if I came across a bit loud I apologize.. I usually skim down
the latest chatter and then just post to the group off the bottom
message, often having no direct bearing on the particular post it spins
off from... Also, I skim a number of groups and topics and I run a
business so I can miss a post that puts a different spin on things...
If I ruffled your feathers it was not intentional...
Let me comment that I absolutely agree with you that claiming a Yagi is
inefficient from the perspective of I2R losses shows a lack of basic
knowledge... Having said that, let me also note that closing the
spacing, i.e. tighter than the classical Yagi-Uda array, and putting
the beam into Supergain territory has consequences... Moxon has a non
mathematical discussion of the supergain antennas with a graph of
spacing v/s gain v/s impedence, and I Krauss mentioned that he designed
his flat top array stimulated from a paper by Brown (I think it was)
where he discussed arrays that have more than additive gain by tight
spacing... Anyway I digress; the point of all this mumble is that these
supergain "Yagi" arrays can have quite high I2R losses... But the
commercial Yagi-Uda today is not in that class...

Anyway, Cheers ... denny / k8do




Jerry:

I didn't really disagree with you, ALL antennas are 100% efficient
radiators (dummy loads are excellent too!), only a real fool would argue
that one!

But this is california, I don't need the infrared radiations all that
much; never had trouble with ice sickles on the 'tenna. grin.

Warmest regards,
JS

Hi John

I didnt mean to imply that any antenna is 100 percent efficient. I would
suggest that the amount of power lost to I squared R losses in a well built
Yagi would be so low that they would be time consuming to evaluate.

I have even thought about how I'd try testing the I^2R losses in a Yagi,
as compared to another antenna design. But, that would be long learning
process for me.

I'd sure like to see Art's data before I'd start a test of yagi
efficiency.

Jerry