Towertalk
[Top] [All Lists]

Re: [TowerTalk] Omnidirectional antenna for domestic contests

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Omnidirectional antenna for domestic contests
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 6 Oct 2015 00:02:54 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Hi Rudy,

You've received some really "off the wall" replies to your question. Some thoughts from the left coast, interspersed below.

On Sun,10/4/2015 7:18 AM, Rudy Bakalov via TowerTalk wrote:
I need antennas for working the US and Canada on 20-15-10 from my VE3 QTH.  I'd 
appreciate any and all suggestions.

Currently considering 1) vertical dipoles and

Verticals are pretty cool, but not much radiation above about 30-40 degrees, so you could be weak in W1/W2/W3/W8/W9.
2) a curtain of 3 stacked dipoles (or inverted Vs) from 10' to 30'.

There are serious misconceptions about the height of horizontal antennas and their effectiveness at low angles. Low horizontal antennas are NOT better for NVIS, they are worse for both short AND long distances. The IDEAL NVIS antenna is about 3/8 wavelength high.


Anything else? Do keep in mind that from VE3 the US is from ~160 to ~330 
degrees azimuth and I do not want to rotate the antenna.

I strongly suggest that you STUDY http://k9yc.com/VertOrHorizontal-Slides.pdf (CAPS added for emphasis). There's "simple" and "too simple." Fan dipoles at a "good" height could work really well for you -- 30-40 ft is a good starting point -- but any good dipole has a null off the end, so you really need two at right angles to work both S and W. With dipoles, the only thing that really matters is the nulls off the ends. Longest US DX for you is CA, OR, WA, so I suggest that you try to be approximately broadside to San Francisco with one fan and to MS with the other, then a simple switch to go between them. The west fan will be killer from KS to CA/OR/WA and will do fine in NTX, etc. The S fan will be great from W1 to FL and TX. There are photos in this presentation

http://k9yc.com/LimitedSpaceAntennasPPT.pdf

of a fan dipole I used in Chicago on a small city lot. Very easy to build -- the spacers are 1/2-in PVC conduit. I used these antennas here in CA before I found space to turn aluminum. :)

73, Jim K9YC

_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk

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