[NLRS] 50Mhz antenna modeling question

[w0zq at aol.com]

Matt, I did a quick check using EZNEC using your dimensions and 0.375" 
elements with the antenna at 12'. The feed point said 38 + j67 with a 
SWR of 4.2. The driven element looks to be too long for resonance ..... 
not sure what the matching idea is. If you shorten the driven element 
to 109" then the feed point is 32 +j0 with a SWR of 1.5 using a direct 
match, perhaps with a 1:1 balun. There is definite forward gain and the 
pattern looks good. One of the beauties of simple yagis is that they 
are very intolerant to design/manufacturing variations and they just 
simply work.   If you made the driven element out of one section of 
telescoping tubing you could tune the ends to achieve the best match 
.... should be close to 109" end to end

73, Jon
W0ZQ


Any way armed with an old DOS program for calculating dimensions I came 
up with
a 2 ele 50Mhz antenna of the following specs:
REF 117.3"
DIR (DRV) 116.53"
BOOM: 30.7"
expected forward gain 4.74 dBd
F/B not very good
element size .375" (maybe .50" at center)
My plan is to feed the driven element with a T match and 1/2W length 
piece of
coax tuned for 50.140.
The "Z" looks like 49 ohms with some inductive component
Any modelers out there that can duplicate my numbers?

KF0Q


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