Colin:

W8AMZ can explain it better than I could ever do if I tried.

Go to the w8amz web site, and find the link to the 80-meter sloper.

You'll see his attempt at an explanation there.


http://www.w8amz.com

73 from Tom Behler:  KB8TYJ

----- Original Message ----- 
From: "Colin McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, November 10, 2012 11:09 PM
Subject: Re: Some antenna theory elmering needed again


> 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
>>
>