what is the trick with these sloaper antennas from w8amz?
Beyond wire, what are they made of?
there has to be some magic trick to get a 30FT wire, with a 25FT counter
poise to work on 80M without a tuner.
73
Colin, V A6BKX
----- Original Message -----
From: "Tom Behler" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, November 10, 2012 8:23 PM
Subject: Some antenna theory elmering needed again
> Hi, all.
>
> As some of you may remember, I purchased two half slopers from W8AMZ
> antennas about a year ago. One was a 160 meter antenna, and the other was
> an 80-meter antenna.
>
> Although it is a compromise antenna for sure, I have had at least some
> success with the 160-meter antenna, in that I can keep my SWR's down below
> 2
> to 1 on the lower half of 160, which is where I mainly like to operate
> anyway.
>
> However, I have not had as much luck with the 80-meter half sloper.
>
> The radiating element of the antenna is roughly 30 feet long, and the
> other
> half of the antenna is grounded to my 40-foot mast as a sort of
> counterpoise. The center of the antenna is up about 30 feet. The antenna
> is fed with about 30 feet of RG8X coax.
>
> The resonant frequency of the antenna is around 3.900, but the sweet spot
> is
> very narrow. My SWR's are up around 5.0 to 1 at both the top and bottom
> of
> the band, with varying SWR's in between, ranging between 2.1 to 1, and 4
> to
> 1.
>
> Based on my experience out at the RV with my G5RV, I decided on a whim to
> try something tonight. I pieced together about 100 feet of coax, and put
> it
> as close to the transmitter as I could get it. When I did this, my SWR's
> improved significantly. The were 3.0 to 1 at the top of the band, 4.1 to
> 1
> at the bottom, and below 2.1 to one through much of the rest of the band.
> The antenna tunes across the band with the TS590 auto-tuner.
>
> My question here is: By doing what I have done here, am I just fooling
> myself into thinking things are better when they really are not? I
> suspect
> that anything I'm gaining by reducing the SWR is going to be lost in all
> the
> extra coax I've now introduced into the system.
>
> Am I correct with my reservations here, or should I not worry about things
> as long as the TS590 auto-tuner can tune the antenna, thereby keeping the
> radio happy?
>
> For more info on the W8AMZ 80-meter half sloper, go to:
>
> http://www.w8amz.com/W8AMZ_SLOPERS_Page.html#80HS
>
>
> Thanks for everyone's patient elmering here.
>
> 73 from Tom Behler: KB8TYJ
>
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