Look ma, no aerial!

[Tim Smith]

Hi
I haven't had time to have a look at the link you included yet, but the
theory of operation of what you are talking about is not dissimilar to the
"leaky coax" used in underground comms systems, as in mining, all over the
world. The only thing that is immediately obvious to me is your suggestion
of putting the coax inside copper tubing, this would effectively shield the
whole antenna from the outside world which of course will render it useless

Regards
Tim

----- Original Message -----
From: <predator at cat.org.au>
To: <wireless at lists.samba.org>
Sent: Wednesday, July 17, 2002 12:14 PM
Subject: Look ma, no aerial!


>
> Reply-to: predator at cat.org.au
>
> I'm in the process of getting enough cash to start another wireless
> project, but this time using not helicals but a high-gain omni, and an AP,
> not an ancient monochannel ISA wavelan with mutant SMZ sockets on it.
>
> Now, there's great omni's around but I dont want to buy them if poss, and
> instead make my own. (leaves more money for lightning arrestors, etc).
>
> However, based on some of the pics at
> http://www.qsl.net/n9zia/wireless/pics/2.4colinear.jpg
>
> it looks probable that one can dispense with an aerial per se, altogether,
> and just stick a straight run of good coax (like, say, my surplus LMR400)
> in the air with precisely placed cuts in the shielding . This brings with
> it some nice advantages, to wit, no connector losses, and given enough
> cable, pretty much arbitrarily large gain. Dunno about the down-angle,
> though 8-(
>
> LMR400 is great stuff but its OD is much larger than the suggested
> 5mm... and this design looks to use a hell of a lot of PTFE tape
> too... maybe the PTFE could be dispensed with, and an appropriate
> diameter of straight copper pipe just fitted straight over the outside of
> the LMR coax.
>
> Has anyone tried this in this group? Or anywhere? Please scream, or laugh,
> or something, if you feel it's doomed to fail 8-)
>
>
>
> Cheeries...
> <predator>
>
>
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>
>
>