[Antennas] Buried window line

2002年12月16日 11:01:30 -0600

Wes, What you says is true to a certain extent but you are forgetting a few
things...
A random length of wire center fed with "window line" can be very effectively used
on all
bands... (try doing that with your heliax fed dipole) also, if your open wire
happen to radiates some,
it is not necessarily lost energy.. It may even help you in some situations.
A balun is not necessary if you use a balanced line tuner... (home built, Johnson
or Nye Matchboxes) Balun losses are minimal anyway. Especially an air wound
balun. (Heathkit
B-1)
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.
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
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.
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.
btw, Welcome to the group Wes. You'll find a lot of happy ladderling users
here.. hi
Best 73, Les, W�OJH
"Wes (N7WS) and Linda" wrote:
> As a newcomer to this forum (Thanks Danny, K6HME) I've been trying to get
> up to speed using the archives.
>> In one message Honest Charlie's Used Cars [email protected] wrote:
>> "Opinions Please...If 450 later line was suspended in
> the center of a ten" PVC pipe and buried would it have
> the properties of one suspended in Air?"
>> As best as I could follow along there were a number of answers which I will
> not repeat.
>> My first thought though is a question, "Why would you want to?"
>> Window line (my preferred nomenclature) has the following advantages
> compared to coaxial lines:
>> 1) Lower cost
> 2) Lower weight
> 3) Potentially lower loss under mismatched conditions
>> It also has the following disadvantages:
>> 4) Radiation from the line unless balance is carefully maintained (extra loss)
> 5) Requires a balun in the system (more loss)
> 6) Increased loss when contaminated by foreign material, especially water
> 7) Needs to be kept separated some distance from other objects
> 8) More fragile
>> Note that unless 4, 5, 6, and 7 are addressed, 3 may not be realized.
>> Returning to the original question my simple answer is "more than likely".
>> However, from a systems viewpoint I think the realization would take heroic
> effort unless the run is very short. The cost is certainly going to
> increase to the point that that advantage is long gone. The weight is a
> non-issue, at least for the underground part.
>> The part about "suspended in the center of" is likely to be difficult to
> achieve.
>> Unless the parameters are widely different from what I imagine my
> suggestion would be to use a length of 7/8" Heliax and be done with it.
>> Wes N7WS
>> - - -
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
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