[600MRG] ERP, EIRP

[Neil Klagge]

 Ed, here is the link to the spreadsheet
https://www.dropbox.com/s/pafykhftdwoxzm5/Rr%20draft2%20for%20630m%20dot%20net.xls?dl=0
73
*´¨)
¸.•´¸.•*´¨) ¸.•*¨)
(¸.•´ (¸.•`   Neil

My Faith website: http://neilsfaith.webs.com/
My ham radio websites: http://w0yse.webs.com/ and http://wg2xsv.webs.com


 

 
Date: Wed, 28 Jan 2015 21:07:51 -0900
To: w0yse at msn.com; n6lf at epud.net; pehamel at cableone.net
From: kl7uw at acsalaska.net
Subject: RE: [600MRG] ERP, EIRP



Would someone please share a link to the spreadsheet.


73, Ed - KL7UW

BTW EZNec was recommended to me by this group when I put up my
inverted-L.  I had winNec4 that I was previously using.  I
built my loading coil based on the impedance predicted by EZNec.  It
turned out I did not need as much inductance as indicated by the model -
so.


At 02:36 PM 1/28/2015, Neil Klagge wrote:

Guys, I
have permission from Frank - XHA to share this. He has had some
interesting exchanges with Roy on EZNEC that relates to its limitation on
antennas less than 1/4 wavelengths. Here is part of Frank's email to me
last week

 

Neil - TKS for
your reply on my question, re: short vertical top loading.  And
before you read further, let me thank you for bringing this "no
sweat" and very valuable "estimating" tool to the
attention of the Below 535 affectionatos!




Ouch - Over the past 10+ years I have numerous casual contacts with Roy
Lewallem, W7EL, the "daddy" of ELNEC, and now
EZNEC.   I wanted to review my experimental findings w.r.t.
what my EZNEC model was predicting, and what my actual measurements were
telling me.  I will freely admit that when it comes to in-depth
antenna theory I am an absolute blundering idiot!


I was modeling various horizontal wire and vertical tube antennas for
160, 80 and 40 meters.  These antennas were either short / low to
the ground, but not to the extent that 630 meter yet alone 2200 meter
antennas are.  My results were frequently way out of the ball park
in comparison to what EZNEC calculated.  


Time after time Roy Lewallen chided me that EZNEC is quite inaccurate
when the antenna model is close to the ground, or short.  Basically,
EZNEC looses its accuracy at heights less than 1/4 wave length. 
Additionally, he added EZNEC does a poor job in estimating ground
conductivity, and the variation of conductivity w.r.t. to depth as
frequency varies.  He also added that the million buck antenna
modeling programs that only the USN and a few universities can afford to
own, and have the ability to properly use and

interpret
 the results,
are not that much better for estimating the performance of
low-to-the-ground / short antennas.  


My last encounter with Roy Lewallen was a low to the ground 160 meter
dipole a friend put up.  At best it was around 25 feet above the
ground.  Scaling by wavelength (a typical EZNEC method) a 630 meter
dipole would be up around 98 feet.  That height is

Herculean
 for most of
us, whether or not we are 630 meter affectionatoes!  Be it 25 feet
up at 160 meters, or 98 feet for 630 meters, it is still about 0.045
wavelength! Definitely low to the ground w.r.t. wavelength.  



Bottom line - The Excel spread sheet is a valuable estimating
tool, just as is EZNEC for low-to-the-ground and / or physically
short (w.r.t. wavelength) antennas.  Without breaking a sweat or
screwing up decimal places modern calculating engines can figure out
stuff to the zillionth decimal place.  Maybe we should all be chided
as not to over extend these calculations to a meaningless number of
significant figures least we fooled into thinking that they are
first principle and ordained from on High.  HI.

---------------------------------


I am wondering what kind of discussion this might stir
up....       ;-) 


*´¨)

¸.•´¸.•*´¨) ¸.•*¨)

(¸.•´ (¸.•`   Neil


My Faith website:
http://neilsfaith.webs.com/

My ham radio websites:
http://w0yse.webs.com/ and
http://wg2xsv.webs.com




 


 


From: n6lf at epud.net

To: kl7uw at acsalaska.net; pehamel at cableone.net; w0yse at msn.com

Subject: RE: [600MRG] ERP, EIRP

Date: Wed, 28 Jan 2015 14:24:03 -0800


Hi guys,


 


Recently Neil has created a worksheet for EIRP based on Fritz’s RN06-32
note on the subject of ERP and EIRP (

http://www.500kc.com/downloads/RN06 ).  At the same time I’ve
been working up an explanation for use as a sidebar in my QEX article on
radiation from verticals.  I’ve attached a copy of the
sidebar.  Read it over and see if it makes sense.  I think it
follows Fritz’s note correctly and hopefully clarifies things a bit.



 


73, Rudy

73, Ed - KL7UW

http://www.kl7uw.com


    "Kits made by KL7UW"

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