Barry,
Its described on page 83 of the the 1937 Frank C Jones Radio Handbook.
The "RCA Spiderweb Antenna System" was one of the antennas that RCA marketed
for their pre-war shortwave radios. The other shortwave radio manufacturers
marketed their own receiving antennas. The RCA Spiderweb used five dipoles cut
for 49, 25, 16, 9 and 5 meters and fed with a twisted wire transmission line,
75 feet long (they emphasize the importance of not cutting the transmission
line!). The 49 meter dipole is loaded to reduce the total length of the antenna
to 37 feet,
Its not much different than today's more common parallel antennas. In the RCA
Spiderweb, the feedpoints of the dipoles are separated vertically over a ten
foot span and the ends of the dipoles are relatively near each other. It
definitely has the appearance of a spiderweb! Its primary advantange was
probably that that it could be supported by only two ropes.
Its kind of the opposite configuration of our typical parallel dipoles, where
the feedpoints are immediately adjacent to each other and the ends of the
dipoles are fanned outward. In the RCA Spiderweb, the ends of the dipoles are
near each other and the wires are fanned out to feedpoints that are separated
by 10 feet.
I'd expect big problems trying to get this antenna to be an acceptable
transmitting antenna. Feeding the spaced dipoles with acceptable performance
will probably be a big headache. Receiving antennas are much more forgiving of
compromises than transmitting antennas!
73!
Frank
W3LPL
---- Original message ----
>Date: Wed, 15 Aug 2007 10:59:50 +0800
>From: "Barry Kirkwood" <barry.kirkwood@gmail.com>
>Subject: [TowerTalk] RCA Spider web antenna
>To: towertalk@contesting.com
>
>Hi all:
>I mentioned this ingenious form of a mulit band parallel dipole in an
>earlier post.
>Have since had feedback that no info can be found via Google etc.
>Am currently travelling in SE Asia, no access to my library, hi.
>I know this antenna was described in the 'Radio Handbooks' and Antenna books
>published by Editors and Engineers before WW II.
>Also it may have been subject to patent.
>Would be grateful if anybody could find a reference to it, better, post it
>somewhere on the web.
>The actual antenna used dipoles cut for the SW AM broadcast bands eg 49m and
>the like.
>The ingenious feature was the way the dipoles were configured such that
>there was good spacing between them, and the whole array could be suspended
>from just two masts.
>Imagine it would be easy to reconfigure for amateur bands.
>tnx es 73
>Barry ZL1Dd
>
>--
>Barry Kirkwood PhD ZL1DD
>barry.kirkwood@gmail.com
>_______________________________________________
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