[TenTec] OT: Question to the group -tuner and dipoles

Jim Brown k9yc at audiosystemsgroup.com
Tue Jul 19 01:28:18 EDT 2016


Hi Carl,

Remember that power on 475 kHz is defined as ERP, so loss in the system 
is OK if we have enough power to throw into the feedline! N6LF has been 
working on this and published something in QEX last summer. It's 
probably on his website.

On Mon,7/18/2016 3:49 PM, Carl Moreschi wrote:
> My particular interest right now is a good antenna for the new 475 khz 
> band that is coming.  I have a 1000 foot dipole at 50 feet and it 
> shows an excellent load at 475 khz.  My belief is this antenna will be 
> more efficient even at a 20 degree takeoff angle than a 50 foot 
> vertical that has a very large and inefficient loading coil and radials. 

Modeling is your friend, and these are very simple antennas to model.  
It allows us to LEARN things rather than "believe" them. The key to 
learning from a model is to plot the results if antennas you want to 
compare ON THE SAME PLOT. The way to do this with NEC is to do the 
design, compute the far field response, and save both horizontal and 
vertical patterns. Then model the second antenna, save those patterns, 
and then import the patterns from the first antenna onto the same graph. 
Now you can clearly see which is better at which angles, and by how much.

73, Jim K9YC



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