[Antennas] Question reg. multiband dipole - balun

Thu, 21 Feb 2002 04:26:21 +0200

Hi Christian

You are bound to hear many conflicting opinions on the subject of balanced
feedline versus unbalanced feedline and antenna tuners.

The golden rule is that one cannot tune a non-resonant antenna with an
antenna tuner via any length of unbalanced feedline.

In other words, you cannot tune your dipole as a multiband antenna if any
part of the feedline is coax.  Your dipole must have a balanced feedline all
the way from the tuner to the dipole.  The person who told you not to add
coax is correct.

But, how to solve your metal window frame problem?

Replace a window pane with Plexiglass or similar transparent plastic
material.  Construct a waterproof feed through the plastic window pane,
which is similar in dimensions to the balanced feedline, and use that
feed-through to take the balanced line to the tuner on your desk.

As long as your window pane feed-through is more than about 300mm from the
metal frame and your balanced line has a clear run to the indoor tuner, your
antenna should work well.

Regards
Deon ZR1DQ
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----- Original Message -----
From: Christian Buenger <[email protected]>
To: <[email protected]>
Sent: Tuesday, February 19, 2002 9:05 PM
Subject: [Antennas] Question reg. multiband dipole - balun

| Hello dipole-user,
|
| I have a question regarding a "normal" multiband (80m-10m) dipole. I am
| planning to set up the following antenna: A horizontal flat-top dipole
abt.
| 2 x 15m long, fed with 450 Ohm window line. So far there are no problems
| but I can't route the window line through the window because the window
has
| metal framing. Window line and metal structures is not working ;(
|
| I thought abt. using an external weatherproof 1:4 balun, connecting the
| balun to the window line (outside the house where no metal structures
| exist) and then route coax into the shack (abt. 2-3 meters). Somebody told
| me that this is not going to work. Unfortunately I can't put the whole
| tuner outside. That would make band changes very uncomfortable and
| additionally the tuner is not weather proof.
|
| Has anybody a solution for this problem? Or experience?
|
| Thanks in advance.
|
| 73
| Christian, DL6KAC
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