[SFDXA] K4FK antenna party results

[Norman Alexander]

Ed,

Creating a short wire segment for the source is a common approach to modeling 
many antennas.  What are the key parameters you are using and I will take a look 
at it in NECWIN+  


Just send me a copy of the WIRE file (OUTPUT).  It can be converted to a 
columnar EXCEL file and then pasted into NECWIN+

 Regards,


Norm




________________________________
From: Ed Callaway <ed at sunrisemicro.com>
To: "k.siwiak at ieee.org" <k.siwiak at ieee.org>
Cc: "SFDXA at mailman.qth.net" <SFDXA at mailman.qth.net>
Sent: Tue, January 17, 2012 8:50:49 AM
Subject: Re: [SFDXA] K4FK antenna party results

Kai,

Thanks - I'd appreciate that.  The specific problem I had was that EZNEC 
wouldn't tolerate more than two wires connected to the source, requiring a 
single wire segment to be used at the (split) source, then branching out to the 
two dipoles.  Simultaneously, however, the wire segment had to be longer than 
0.02 wavelength, plus some other restrictions, and when all the requirements 
were met simultaneously the geometric arrangement ended up being a single dipole 
again.  Very clever, these simulators . . . .

Ed.

From: Kai Siwiak [mailto:k.siwiak at ieee.org]
Sent: Tuesday, January 17, 2012 8:43 AM
To: Ed Callaway
Cc: SFDXA at mailman.qth.net
Subject: Re: [SFDXA] K4FK antenna party results

Hi Ed,
Nice that the dipoles are ok now. When I get back I can do a NEC analysis (I use 
Arie Voor's 4NEC2 - free, and very nice interface).
Alternatively try a purely analytical mutual coupling analysis, but for straight 
dipoles rather than Vee.

I should be back within a few days, and would like to help with the 80/160 
dipoles.

73
Kai, KE4PT/3



Ed Callaway wrote:

Pete, N8PR, and I got the 40/30m dipoles re-strung Saturday, using fresh wire 
and UV-resistant Dacron rope.  The most interesting thing to note of the 
experience was that the calculated lengths were off by a foot for the two 
dipoles - too short on 30m, too long on 40m.  Corrections were made, and 
everything now tunes up where it should.



Pete and I aren't sure why the resonances were so far off, and in opposite 
directions.  I was expecting some interaction, and a move upward in resonance as 
the wires were moved from straight dipole to their inverted-vee configuration, 
but this surprised me.  I had spent a few hours the night before on EZNEC trying 
to model crossed dipoles, but for a novice at EZNEC it turns out to be hard to 
simulate that.  Comments welcome.



Regarding 80/160m, the north sides of both dipoles have broken from the center 
point and are lying on the roof, while the south sides of both dipoles and the 
feedline are still in their proper place on the tower.  Another antenna party, 
this one involving actual tower-climbing, will be required to correct the 
problem.



Ed N4II.



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______________________________________________________________
South Florida DX Assoc. Reflector

SFDXA WebSite: http://qsl.net/k4fk
SFDXA Repeater 147.33+ 103.5 Tone
DX Net Wed 7:30 PM Repeater
EchoLink: K4FK-R
To Post: mailto:SFDXA at mailman.qth.net
Info:http://mailman.qth.net/mailman/listinfo/sfdxa

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