Re: [IRCA] How to phase BOG's? (Jim Glover)

[Jim Glover <psykey@xxxxxxxxxxxx>]

There is no internal ferrite bar antenna.  My guess is that I was
giving the antenna system a ground plane.  The BOG was simply
inserted into the center of the chassis SO-239.  I'd made no
connection to the outer section of the SO-239 (ground).  Under
other circumstances--e.g. if I'd been powering the transceiver
from the car battery--my transceiver would have been grounded to
the car.  But since I was powering the transceiver from its
internal battery, there was no "other side" of the antenna.  By
placing my hand on the metal body of the transceiver, I was
probably creating a capacitive coupling between my body and the
transceiver.  My body was also capacitively coupled to the car.
The result was probably that the car's body became a "ground
plane" or "counterpoise" or whatever you want to think of it,
providing the antenna with an "other side".

In a future test, I will try grounding the transceiver to the
car body to see if I get the same type of result.  If I do,
that will, IMO, strongly suggest that I'm barking up the right
tree here.

I'm thinking there are two big factors limiting the Beverage-ish
performance of my BOG.  One is that 500' at 530 KHz to 1700 KHz
is relatively short, in terms of a wavelength.  Even if you
allow for the antenna ending up much longer electrically by 
virtue of its proximity to ground, it still doesn't get long
enough to become directional off the end.  The other big factor
is probably good soil conductivity.  I had already been wondering
about this factor--then Bruce Conti (replying on the NRC-AM list) 
mentioned that BOG's perform better over soil with low conductivity.
According to the maps, the soil conductivity around here is on the
high side.

On Tue, Sep 29, 2009 at 03:50:15AM -0700, Russ Edmunds wrote:
> There has to be some explanation for why there was so little difference between the car radio and the BOG. Part of that is the length, part is no termination and part is no matching transformer. But it seems as if there should be something else.
> 
> That thought is magnified by the increase in signal strengths by putting a hand on the receiver, although since I'm not at all familiar with the receiver in question, if it has an internal ferrite bar antenna, that could partially explain it.
> 
> 
> Russ Edmunds
> Blue Bell, PA ( 360' ASL )
> [15 mi NNW of Philadelphia]
> 40:08:45N; 75:16:04W, Grid FN20id
> <wb2bjh@xxxxxxxxx>
> FM: Yamaha T-80 & Onkyo T-450RDS w/ APS9B @15'
> AM: Modified Sony ICF 2010 barefoot
> 
> 
> --- On Tue, 9/29/09, Jim Glover <psykey@xxxxxxxxxxxx> wrote:
> 
> > From: Jim Glover <psykey@xxxxxxxxxxxx>
> > Subject: Re: [IRCA] How to phase BOG's? (Jim Glover)
> > To: "Mailing list for the International Radio Club of America" <irca@xxxxxxxxxxxxxxxx>
> > Date: Tuesday, September 29, 2009, 12:51 AM
> > On Mon, Sep 28, 2009 at 06:30:57PM
> > -0400, Gil Stacy wrote:
> > > Jim, Dave:
> > > Dave, I doubt if Jim's car antenna was coupling with
> > the BOG.
> > 
> > I can rule it out.  I rolled the BOG up, and then
> > checked many
> > of the stations again on my car radio.  The BOG was
> > now once
> > again a spool of wire in the trunk of my car, and the
> > sations
> > were still rolling in.
> > 
> > Thanks, Gil, for the additional information about phasing
> > these things.  I don't really need to spend another
> > C-note or
> > two on one of these phasers ... but oh my, it is tempting.
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> 
>       
> 
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