Re: antenna farm

Posted by N5GE on Dec 15, 2009; 7:40pm
URL: http://elecraft.85.s1.nabble.com/antenna-farm-tp4165832p4171977.html

On Mon, 14 Dec 2009 11:58:26 -0800, "Ron D'Eau Claire" <[hidden email]>
wrote:

Yes you did open the flood gate.  Antenna opinions are like noses.
Every one has one...

As Ron say's,  If you can't get a dipole up 1/2wl you will be sending
most of your radiated output and receiving at high angles, which won't
be what you want unless you plan to do a lot of local rag chewing.

Here's a real life test that I made:  

I have an 80m half sloper on my tower sloping from 38 feet which does
pretty well working 360 degrees around (the tower becomes the radiator
when using this type of sloper).  A couple of weeks ago I put an 80m
inverted vee up and compared the two.  The inverted vee could not even
hear the European signals, but could hear signals within a few hundred
miles very well.  The reason for that was because the inverted V (at
38 feet) was radiating the largest amount of energy straight up at 90
degrees (verified with EZNEC 5.0).

73,

Tom, N5GE

[hidden email]
K3 #806 with SUB RX, K3 #1055, PR6,
XV144, XV432, KRC2,
W1, 2 W2's and other small kits

1 K144XV on order

http://www.n5ge.com
http://www.swotrc.net

>As Ken mentioned, height is an important factor in a horizontal or
>semi-horizontal antenna. There's limited "gain" in any direction at low
>angles unless the radiator is 1/2 wavelength above ground. That's why most
>of us have to live with little directivity on the lower bands.
>
>The option is to consider verticals. Unless you are living on salt water (or
>atop a sheet of copper), or can make the vertical a full 1/2 wave high, the
>vertical won't be as efficient as doublet or dipole, but a vertical will
>produce typically much better signals at lower angles of radiation than a
>horizontal antenna (under 1/2 wave high) and doesn't require a huge
>'footprint'. Also you can phase multiple verticals for directivity and even
>design them so you can use them for supports for horizontal wires on the
>higher bands.
>
>You've probably noticed that 45 foot verticals are being heavily promoted
>these days. That's an old design that is very handy for limited space. It
>provides low angles of radiation on all bands up through 20 meters where
>it's 5/8 wavelength high (on bands where it's more than 5/8 wavelength the
>angle of the main lobe rises from the horizontal and minor lobes appear at
>high angles). Down on 80 meters it's just a bit shy of 1/4 wavelength. With
>a good ground system it can produce excellent results down there and even on
>160 - especially when compared with the short, low (in wavelengths above
>ground) antennas most of us are forced to use on those bands
>
>Ron AC7AC

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html