[600MRG] TNX for Replies, Ending Thread - RF Ammeter Placement and Antenna Feedpoint Location

[Neil Klagge]

So much for trying to end your thread, Andy....hihi


Responding to Eric's comment about sloped top loading wires: The way I have used my spreadsheet to find Rr with my sloped wires is mentioned in my note 5 at the bottom of the SS.


(5) If the top load wires are sloping downward at a ~45 degree angle to the vertical section, the Rr will be more like  the AVERAGE between the Rr with NO top loading, and the Rr with the top load running HORIZONTALLY.


Again, this is just a theory, or an educated guess, but seems to be close in my case. I get Rr of .35 when averaging as in the statement above, and my modeling of EZnec gets me .36 ohms. Seeing these numbers makes me happy, but that could be just a coincidence in my case.


Thats my $2 worth (inflation due to an awesome rise the the stock market in the past year or so, LOL)


73
Neil, w0yse, CN85rq
Vancouver, WA

My ham radio websites: http://w0yse.webs.com/ and http://wg2xsv.webs.com
<http://wg2xsv.webs.com>
My Faith website: http://neilsfaith.webs.com/
________________________________
From: 600mrg-bounces at mailman.qth.net <600mrg-bounces at mailman.qth.net> on behalf of Gedas <w8bya at mchsi.com>
Sent: Monday, March 12, 2018 3:27:56 PM
To: no3m at no3m.net; 600mrg at mailman.qth.net
Subject: Re: [600MRG] TNX for Replies, Ending Thread - RF Ammeter Placement and Antenna Feedpoint Location


ok so is it safe for me to summarize it this way.....unless one can accurately measure all of the other "collective losses" there does not seem to be a practical method available for physically measuring R(rad) without supplemental data from models of the antenna.

Gedas, W8BYA

Gallery at http://w8bya.com
Light travels faster than sound....
This is why some people appear bright until you hear them speak.

On 3/12/2018 6:11 PM, Eric NO3M wrote:
The "measured" value using an analyzer into the unmatched end of the loading circuit will include all collective losses + R(rad), which is useful for calculating the efficiency.  Determining R(rad) itself using a reasonably accurate model is still the most practical method as Ed mentions.  There are other tools like spreadsheets and online calculators floating around that can come close if the antenna is generic (ie. flat-top loaded monopole).  I don't think these alternate methods handle situations like sloped top loading.

73 Eric NO3M


On 03/12/2018 05:42 PM, Gedas wrote:

Hi Ed, so good to hear from you again ! I chose my words very carefully. Eric used the term Measured and that is what I wanted to learn more about. I use and enjoy modeling and know of several calculated approaches to arrived at the value. But again, that word "measured" got my attn. and was wondering if he would be willing to share any practical approaches at arriving at a value of R(rad)...73

Gedas, W8BYA







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