[Elecraft] Antennas for use with Elecraft T1 ATU

[Don Wilhelm]

Kieth,

This is a portable field antenna for me, and I have made the feedline from a
pair of twisted #22 teflon insulated wires.  Some years back, someone on
QRP-L did some tests on various feedlines, and this turned out to have good
loss characteristics, and it is flexible and lightweight which are two major
advantages for my use.  It rolls up nicely and the teflon insulation helps
keep it from tangling and snarling on other objects.  YMMV.  Jim N2GO is my
source of the teflon wire, he posts occasionally on QRP-L.

If I were using either a 44 or 88 foot flatop as a permanent antenna, I
would do it differently.  I would use #14 wire for the radiating section and
well positioned 450 ohm ladder line (or homebrew parallel line spaced about
4 inches apart) for the feedline.  The advantage of the 44 foot antenna is
that you know that the radiation is broadside to the antenna and without
side lobes for operation on 40 through 10 meters, and the 88 foot length is
similar for 80 through 20 meters.  Yes, it is only 2/3 of a half wave long
on the lowest band, and is not as efficient there, but this is a multiband
antenna, and some compromises must be made for any antenna, particularly a
multiband one.  In my case, I have accepted compromises both for portable
usability and multi-band use, but 'it don't work too bad'!

The feedline length of 25 feet is just what is convenient for my situation.
The proper feedline length should always be 'long enough to reach from the
shack to the antenna'!  The feedline length will change the impedance seen
at the shack end, but if your tuner will match that impedance, the exact
value is unimportant.  If you want information on how this impedance
transformation works in laymen's terms, take a look at the Antenna,
Transmission lines, and Tuners article on my website
http://w3fpr.qrpradio.com - There really is no magic in antennas, it just
seems that way at times especially if you do not know some basic
principles - at least enough to be aware of the ridiculous claims made by
some.  The fact that someone worked DXCC in 2 months with a wet noodle does
not say anything about the real characteristics  of that antenna.

73,
Don W3FPR


> -----Original Message-----
>
> Right now my feedline length is 0.  I have not built the antenna
> yet.  I work about 20 mins from HRO and hope to swing over
> there at lunch.  I have seen ladder line there before.
>
> It sounds like the 22 feet per side is a common length that
> works for people.  I will start with that. It also sounds like I
> should test different feedline lengths as well to get the best
> setup.   I also like the idea that was posted about using
> Anderson Power Pole connecters to extend the dipole for good
> 80M coverage.  I have those lying around and will see about
> giving that a try.
>
> I have a bunch of wire ready to cut to various lengths to try
> this stuff out.  The goal is to get a couple of antennas built so I
> can operate outside and hone the CW that I have been
> practicing.  After that...I can move into experimentation mode.
>
> With your 25 foot feedline, are you using open ladder line or
> some twinlead from Radio Shack etc?
>
> Thanks for all the advice.  I am learning a lot.
>
> 73 de Keith KB3ILS
>