[TowerTalk] Scaled Antenna
Mon, 24 Apr 2000 16:50:11 EDT
In a message dated 23.04.00 19:24:00 Pacific Daylight Time,
<< Well, it's pretty tough to scale things correctly.
The original Quad data came from scaled antennas, and it turns
out that data had scaling errors that made the quads look better
than they actually were.
We are all in the same boat. We can scale and model all we want,
but until we actually build and measure the actual antenna we can
never be sure how it will really play.
The only thing any of our antennas have to do is make us happy,
no matter how they really work. Anyway, have fun.
73, Tom W8JI
There is nothing easier to scale than a quad with all the wire sizes
available. Spacing and wire length can be scaled exactly. Why was there or
what were scaling errors? Wire size is critical. Yagi's are really tough to
scale in getting the exact tubing diameter. I use model airplane brass
tubing and then use the computer to duplicate the pattern with available
tubing that will be used.
Quads can be scaled to any TV channel and 88-108 MHz carrier and use that as
a RF source for receive--24 hours a day. The least scaling is desirable
although I haven't found any evidence proper scaling doesn't work out with
5:1 scaling as has been claimed by those with improper facilities and skills.
The Q doesn't scale. Find out what their polarization is first. My
antennas make me real happy with they check out compared to the scaled model.
I've been able to predict fairly well how it will work just by observing the
vertical pattern. I have a JFD FS meter for TV and FM that is very useful
for this work. K7GCO
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