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From: "Hideho YAMAMURA" <pba01030@nifty.com>
To: <rsgb_lf_group@blacksheep.org>
References: <53519F43.2020709@netspace.net.au> <5351A3E1.90603@virginbroadband.com.au> <5351AEBA.10207@netspace.net.au> <5351B656.6030809@virginbroadband.com.au>
In-Reply-To: <5351B656.6030809@virginbroadband.com.au>
Date: Sat, 19 Apr 2014 19:01:04 +0900
Message-ID: <003c01cf5bb6$46eb8790$d4c296b0$@nifty.com>
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Subject: RE: LF:EWE antenna
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Hello Edgar,

I used to play with Flag Antenna, a ground independent EWE. 
I wrote an article in 1995.

The terminating resistance is basically around 
the characteristic impedance of the horizontal wire 
(parallel wire, if a Flag)

Your dimensions give 533ohm.
  5mm diameter wire, 9mx2=18m spacing parallel wire
  the characteristic impedance Z0 is 1066ohm
    Z0 = 120 ln(d/2a), d=spacing, 2a=diameter
 divided by 2 for EWE.

When you change the terminating resistance, the null shape changes.
A higher value gives you two split nulls (sometime helpful), 
A lower value gives you less deep null (not good).

Before that, the terminating resistance is affected by the vertical wire,
so you have to cut and try for compensation.
Very roughly, 50% to 80% of Z0.

The above two combined, Z0 is a good start.

Also, my experience and simulation showed that the null is good
when the aspect ratio (length/width) is 3 to 5, for a Flag.(6 to 10 for EWE)
This is due to the long vertical wire compared to horizontal.
So, it may be worth trying a longer or lower EWE.
This suggestion is based on Flag, so it may not work well for EWE.

BTW, in which direction do you plan to set the beam ?
I wish you consider JA too. You may put a switch.
My ant is down for the moment, but plan to put it back shortly.

73s,

Hideho YAMAMURA, JF1DMQ/AA6VE


> -----Original Message-----
> From: owner-rsgb_lf_group@blacksheep.org
> [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of edgar
> Sent: Saturday, April 19, 2014 8:34 AM
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF:EWE antenna
> 
> Hi Richard,
> 
> That would be great.
> 
> Thank you.
> 
> Regards, Edgar
> Moonah, Tasmania.