[Lowfer] Final design for new antenna at Beacon " XR "

[Andy - KU4XR]

Hi Paul:

Hope you are well ?? I looked at your antenna on Dex's site. I had 
considered trying a top hat design like that here, but it probably
would not stay in the air too long. In my layout, I have to be very
careful with capacitance !! the wrong kind, can really hurt the
signal here. The wrong kind of capacitance is " series " capacitance
in the vertical radiating section. The capacitance the top hat provides
to ground reference is greatly beneficial, but any capacitance that is
presented in series with the radiator actually subtracts from the
overall capacitance of the antenna in its reference to ground return.
I have to be very careful about coupling effects from the mobile home
siding, and trees that are 50 feet away, all pines that stay with me
year round. I have had many recommendations to do a multiple wire
vertical, however the added series, and coupling capacitance that a
multi wire radiator would present would probably do more harm than
good in my layout. That could be a big debating point I suppose, but
that is the case for my antenna layout. I want maximum capacitance at
the top, and minimum in the vertical run, because it will subtract
from what's at the top. My best, and compromisied any way you look at
it, is to use a single wire vertical radiator, spaced as far from the
side of the mobile home as is possible, kept as vertically straight as
possible, and the horizontal portion coming into the shack, also as
straight, and short as possible. At least that's the way it has made
sense to me, hi - hi !!  73 for now, hope to be back on soon :


Andy - KU4XR - EM75xr - Friendsville, TN. USA
LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )

*** Temporarily OFF, while constructing a new antenna ***

Coordinates:  N:  35º 43' 54" - W:  84º 3' 16"
http://www.myspace.com/beaconxr


--- On Fri, 7/30/10, Paul Daulton <k5wms at centurytel.net> wrote:

> From: Paul Daulton <k5wms at centurytel.net>
> Subject: Re: [Lowfer] Final design for new antenna at Beacon &quot; XR &quot;
> To: lowfer at mailman.qth.net
> Date: Friday, July 30, 2010, 2:08 PM
> Andy, capacatance is the key to
> sucess of a lowfer verticle. The more 
> cap you have the less coil needed and thus the more
> efficent the ant is. 
> 
> I was suprised at the cap of my lowfer ant, 330pf, and I
> originally 
> attributed it to the base. Look at pictures of my antenna
> on Dex's site 
> or on Part15 files. My top hat is a wire  cage formed
> by pvc cross 
> arms. the skeleton forms a cube or approximates a sphere.
> In the Arrl 
> ant book the formula for cap on a top hat says the sphere
> has 1.6 times 
> the cap of a disk of the  same dimensions. Also look
> at running 
> multiple verticle wires. The tower looks like a cylinder
> and has more 
> cap than a single wire. I built  mine out of what I
> had, but it looks 
> like I lucked into a good combination. 
> 
> Good luck. 
> 
> Paul k5wms
>