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noob coax question - RF Cafe Forums
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crossection |
Post subject: noob coax question
Posted: Sun Oct 05, 2008 2:14 pm
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Joined: Sun Oct 05, 2008 12:44 pm Posts: 1
Location: CA |
Apologies if this isn't the right forum for this question...
I need to build
a coaxial line that will have perforations in the outer conductor to allow me to see
the interior. The visual access section will be about an inch in length, and the coax
is built from 1.5" i.d. copper tube (outer conductor) and 0.375" copper rod (inner conductor).
Perforations will be small - about 1mm diameter on 4mm pitch arrayed around
and along the 1" sight section. Frequency is 2.45 GHz, so the perforations are small
compared to the wavelength (dielectric is air).
My question is whether I'll
have significant radiation from the perf'ed section - significant would be ~1% or more
of the incident power. I have successfully used perforations to give nonradiating visual
access in rectangular waveguide (symmetric hole patterns centered on the short wall).
My math says that a coax wall won't radiate under these conditions, but since
I've never worked with coax before, I don't have full confidence in my math model. I'd
like to get another opinion before I cut metal and maybe warm up the room in an unanticipated
way!
Thanks for your help.
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WA9WVX
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Post subject: Radiating Coaxial Feedline
Posted: Wed Dec 24, 2008 12:13 am
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Joined: Mon Jul 07, 2008 9:42 pm Posts: 7
Location: Northern, IL |
Sounds like you want to re-invent
Andrew's Radiax Coaxial RF Cable. This
has also been known as Leaky Line. This 50-Ohm
RF cable has been available for 40 or 50 years and is heavily used in large multi-level
buildings such as: hospitals, hotels, downtown offices, football, Basketball, baseball,
horse racing stadiums, museums and tunnels. The RF cable allows signals to penetrate
areas where outside antennas are unable to reach marginal or dead spots within the buildings
and it allows the signals to work both ways in a two-way radio communications system.
Andrew
is now a division of Commscope and here's their
website:
http://www.commscope.com/andrew/eng/product/trans_line_sys/coaxial/radiating/1206639_13611.html
73,
Dan WA9WVX
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Posted 11/12/2012
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