Towertalk
[Top] [All Lists]

[TowerTalk] Cage Antennas

To: <towertalk@contesting.com>
Subject: [TowerTalk] Cage Antennas
From: pmcinnish@worldnet.att.net (Paul McInnish - K4BET)
Date: Wed, 26 Aug 1998 14:02:52 -0400
This is a multi-part message in MIME format.
--------------649CB60E38A11E8C7D5CD201
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Lee... used a cage!  As soon as I get my new tower up, its going back up,
again!  Experimented with many configurations... the biggest advantage of using
a cage is the extreme broad bandwidth and - why I don't yet fully understand -
a most dramatic reduction in noise! Depending on the angle of the legs, you can
adjust to get a virtual 52 ohm match @ apex. This confirmed with a rather
sophisticated impedance bridge and TDR (Time Domain Reflectrometer).

Yep, mine is in Inv V config. with apex @ 72'

3 conductors would be virtually useless and would only help slightly and would
not be enough improvement to justify the expense & effort.  You need a minimum
of 8 conductors and assuming operating on 75 mtrs.... evenly spaced & a minimum
diameter of 15"!!!  I know, you'll probably get some messages that I am all wet
with these figures but this was come about by a lot of hard work, expermenting,
wasted money, etc., etc.

I have mine actually cut for 160 mtrs. & with the antenna tuner... works ALL
bands... up to & including 10 mtrs. You'll notice one of the most dramatic
increases in signal strength on receive that you have ever had! The reports you
get on xmit. will be exciting.  I had a regular inv. V & switching between the
two... I get several "S" units increase reports.  I am accused of runing an amp
when switching antenna to the cage!

Word to the wise... takes a lot (several thousand feet) of copper wire (use
small 18 to 22 gauge, stranded) and find some 15" PVC pipe & find a machine
shop that has one heck-uv-a-big band saw and have him cut you some rings to
separate and hold the conductors.

I can assure you, once you use a well constructed cage, you'll swear off other
wire antennas!

Keep me posted!
Paul - K4BET



Lee Buller wrote:

> I have been looking for a project to work on this fall (when it cools off)
> and have been looking at a "cage" antenna for 80 meters.  I think that is
> the appropriate name.  If my understanding is correct, a cage antenna is
> more that one wire on each side of the dipole.  I've read that in the
> golden years of radio, the cage was used quite extensively with up to six
> wires per side.
>
> My plan is to use three wires using Lexan spacers.  I plan to do some
> experiementation here, but my first plan is to make all three wires the
> same length and cut the antenna for the middle of the bands.  AS I
> understand this type of antenna, the construction of the antenna makes the
> wire to "appear" thicker...which increases bandwidth.
>
> A variation would be to cut one wire for 3.5...aother for 3.8 and still
> another for 4.0.
>
> Can you use these in Inverted  Vee configuration or do they need to be
> flat-top?
>
> Has anyone out there fooled with this type of antenna and if so....what are
> the pitfalls?
>
> Lee Buller
> k0wa@southwind.net
>
> --
> FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
> Submissions:              towertalk@contesting.com
> Administrative requests:  towertalk-REQUEST@contesting.com
> Problems:                 owner-towertalk@contesting.com
> Search:                   http://www.contesting.com/km9p/search.htm



--------------649CB60E38A11E8C7D5CD201
Content-Type: text/x-vcard; charset=us-ascii; name="vcard.vcf"
Content-Transfer-Encoding: 7bit
Content-Description: Card for Paul McInnish
Content-Disposition: attachment; filename="vcard.vcf"

begin:          vcard
fn:             Paul McInnish
n:              McInnish;Paul
org:            Meiji Corp.
email;internet: pmcinnish@worldnet.att.net
title:          Manager, SE Region
x-mozilla-cpt:  ;0
x-mozilla-html: FALSE
version:        2.1
end:            vcard


--------------649CB60E38A11E8C7D5CD201--


--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm


<Prev in Thread] Current Thread [Next in Thread>