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Old September 29th 06, 01:10 PM posted to rec.radio.amateur.antenna
jawod jawod is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 303
Default First homebrew antenna and a question

jawod wrote:
I spent the day lowering the folded dipole that I BOUGHT. I was unable
until recently to find how bad the SWR was on most bands. The only
reasonable SWR was on 17 meters.

So, I replaced it with a homemade G5RV, measured appropiately for each
leg of the dipole (14AWG) and for the 300 ohm window line to R/G8U.

I now find reasonable SWR on most bands (WARC, not so much). Here's the
deal: min SWR comes in right at 3.5 MHz, 6.75, 13.43, 18.07 and 29.06.
It appears that I made the classic newbie mistake...antenna too short.

Now, since I am using an ATU, I think this should be close enough for
acceptable efficiency (at least for 80, 40, 20, 17 and 10 meters).

What do you think?

John
AB8O

PS, When I get the time, I'll try EZNEC but for now, I just want to work
what I hear for a change (!)

Update:

Well, yes, the antenna was too long (not too short). I decided to lower
the antenna and shorten each leg by 18 inches. Now it's back up about
45 feet, sloping to about 25 feet. (No change from before.)

Now, SWR dips are at 3.610, 6.710 and 13.580 MHz.

These are not what was expected. Oddly, on 40M SWR dip went further
away from the band edge (as if dipole was lengthened).
I did not change the 300 ohm window line (at 31 feet).

From what I've read here and elsewhere, I should note 80 and 20M
performance as primary considerations.

I'm a little nervous about shortening it further.

John
AB8O