[Antennas] Buried window line

[Wes (N7WS) and Linda]

At 11:01 AM 12/16/2002 -0600, Les Severson wrote:
>Wes,  What you says is true to a certain extent but you are forgetting a few
>things...

Not necessarily forgotten, just unsaid <g>

>A random length of wire center fed with "window line" can be very
effectively used on all bands... 

Well, it can be *matched* on all bands.  What the radiation pattern may be
is another story. And it should be at least 3/8 lambda on the lowest
frequency to be effective.

(try doing that with your heliax fed dipole)  

Actually, if you ran two dipoles in parallel (as I do) cut for 40 and 80
meters and fed with 200' of 7/8" Heliax and a decent tuner (Qc=1000,
Ql=200) the total worst-case loss @28MHz is a bit less than 3 dB.  Using
Wireman 552 and a similar tuner, the loss is a shade over 1 dB.  This is
*much* less difference than the nay Sayers who are squirting their lines
with the garden hose are experiencing, but are totally unaware of.

Furthermore, a case can be made that the simplicity of the coax feed
outweighs the extra 2 dB loss.  YMMV.

> also, if your open wire happen to radiates some, it is not necessarily
lost energy..  

No, but did it do anything useful, or did it create additional problems?

>It may even help you in some situations.

Maybe, but I would prefer to have predictable operation.

>A balun is not necessary if you use a balanced line tuner... (home built,
Johnson or Nye Matchboxes) 

True, but how many actually use these?  Most folks depend on the built-in
balun in their MFJ or something similar and this is horrible.  But
ignorance is bliss.

>Balun losses are minimal anyway. Especially an air wound balun. (Heathkit
B-1)

I don't believe that the air wound baluns are very effective but I've been
wrong before.  As I stated in my published remarks, a fraction of a dB loss
in a balun is just as bad as a fraction of a dB in the transmission line.
Under the extreme SWR conditions encountered in off-resonant operation the
loss is magnified significantly.


>Losses, for even a couple hundred feet of balanced feedline, are
comparable  to hardline's losses. The need to separate from other objects
refers to "metal" objects in it's narrow field.

Actually, it depends.  If a balanced line is operated over a ground plane
with the line uniformly spaced, the major effect is an increase in the line
Zo. "Reference Data for Engineers" has equations for this. This is much
preferable to operating the line in close proximity to a lossy dielectric
and/or in a non-symmetric situation.

>A 1 ft wooden stick or fiberglass brace is sufficient to keep it away from
your rain gutter.  Rain has very minimal effect but I seldom operate in
rainstorms anyway...  hi

Me neither, I'm in Tucson <g>. What's a rain gutter?

>Good ladder line,  made with #14 stranded conductors is certainly not
fragile.
(available at AES)   It can probably outlast your rig if properly connected
to the antenna.

Not in the AZ sunshine.  My radio has lasted a lot longer than a year.

>One thing that I do agree with you on is that,  if it is necessary to bury
your feedline, you're probably better off to put up an antenna for each
band and feed with undergound buryable coax.  The expense and hassle of
that makes me cringe.

Every situation is different.  Window line and other balanced lines have
their place.  However, there has come to be (IMHO) too much baloney sliced
that says that they are the answer to any situation.  They are not. 

I give for example my situation.  I have a single tower that supports my
20-meter monoband Yagi and the dipole pair described above.  The tower is
about 175' from the shack.  My shack is in a windowless room with masonry
wall that is 10" thick and there are no roof overhangs.  There is no way
I'm going to dangle a piece of window line from the house to the tower,
especially to feed a resonant antenna.

Therefore, I have a run of Heliax (bought surplus for a buck a foot)
running from the house to the tower.  Since I have additional control
cables going to the tower, the Heliax is run in 2" PVC conduit that is
buried near the house and run above ground from there.  A remote coax
switch handles the change between antennas.  A homemade ferrite sleeve
balun is located at the dipole feed.

That's it.  One transmission line, no tuner, no muss, no fuss.  Don't care
if it rains or the wind blows.  Works the same every time.  If I want more
bands, I'll add some traps.


>btw,  Welcome to the group Wes. 

Thanks, glad to be here.

> You'll find a lot of happy ladderling users here.. hi

I see that.  Some of them are deliriously happy <g>.

Regards,

Wes  N7WS