Re: Folded dipole query

---------

From: NONE (wynnt@utkux.utcc.utk.edu)
Date: Sat Dec 23 1995 - 09:43:18 EST


On Fri, 22 Dec 1995 11:48:52 EST "Reich, Christopher N"
<cnr@rfpo2.rfc.comm.harris.com> wrote:

>Does anyone have any experience or thoughts using a non-resonant folded
>dipole with an antenna tuner for multi-band operation? I can't help but
>wonder if the broad-banded characteristics of a resonant folded dipole will
>make the antenna tuner adjustements less "touchy".

On Fri, 22 Dec 1995 20:51:41 EST cebik@utkvx.utcc.utk.edu wrote:

<results of modeling a 40M FD fed from 40M thru 10M, eliminated for brevity>

A Cantenna(R), Heathkit's name for their famous oil cooled
1KW Dummy Load, at 50 ft., has a 50 +0j feed; so can a center fed 1/2 wave
single wire dipole at xx feet. Only one of the two is a decent antenna.;-)
Also, as cebik and others have mentioned, given certain rogue combo's of
feedline, antenna, and drive freq., one can overtax an antenna tuner
or balun and/or transmitter.

>From an experience point of view:

My 40M FD, fed with twinlead loads well with my ATU on 30M, is relatively
broadbanded on 30M, and is efficient. The same loads kinky with my ATU
on 20M, is touchy, and sucks as far as efficiency. The same on 17M? -
results are like 20M only worse. (wynnt's definition of good antenna
efficiency is that he can use it to work QRP what he can hear most of
the time).

So another answer to the original question is - driving a FD with
off-resonance frequencies is a mixed bag.

If one wants a fair multiband single antenna with ATU support, try
a G5RV or a center fed dipole, 1/2 wave on the lowest freq, feed with
450 or 600 ohm line and a robust ATU. If one wants a good single band
antenna that can accomodate relatively cheap and efficient feedline, try
a folded dipole. For a good fat dipole (basically a two wire cage)
article see "The ARRL Antenna Compendium Vol.2" p. 106.

Happy holidays,
wynnt


Search QRP-L Archives

[ QRP-L Archive | ]
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 ]

---------

This archive was generated by hypermail 2b29 on Fri Jun 02 2000 - 11:28:59 EDT

kd4ab@kd4ab.org