[bars] Impedance of yagi

[Tim KC1RET]

So I'm trying to throw together a 3el 6m yagi for the VHF contest this 
weekend. I built one based on a design for a wire + PVC beam I found on 
da Google (http://ehpes.com/n6mw/WireYagi2.pdf 
<http://ehpes.com/n6mw/WireYagi2.pdf>). Mine has a bit less duck tape. ;-)

I tested only the driven element with my nanoVNA, spot on 1.1 at my 
target of 50.2 (FT8). I added the reflector - still 1.1. (All 
measurements taken at about 10ft. elevation). I added the director - the 
lowest SWR is now 2.5:1 at the same freq. (the SWR low point did not 
change).

The measured impedance dropped from 50.2 to around 30 after adding the 
director. I took the wire off the director element support (aka PVC 
pipe) and the SWR went back to 1.1:1.  I did check that the elements 
were parallel (as best as can be accomplished with PVC tubing and bits 
of cutting board).

What variables in the director (length, spacing from DE, etc.) would 
cause this?

73

Tim - KC1RET
-- 

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      Tim Carter - KC1RET

			

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