OWA yagi tapering dependency...
 

Hi

Original OWA 14MHz yagi element diameters and element positions make
good results on simulator.
Now I have plan to use tapering from older elements already available,
but this seems to make too much offset
compared to original OWA in simulator. ( The element tapering would be
in three sections, 1st: diam. 1" , length 72", 2nd: diam. 0.875",
length 66" and the tip diam 0.5" instead of four sections used in the
original )

What could be reliable optimizing simulator ( free ware ) to fine tune
the element lengths and positions ?
Or is it even possible to get equal F/B and impedance matching as the
original dimensions show ?

br Kari B

OWA yagi tapering dependency...
 

I built some 15m and 10m owa's a few years ago and used slightly different
tapering. What I did was to first find the resonant frequency of each
element as designed, then match the resonant frequency of the element with
the new taper by adjusting the tip length. The overall design came out very
close to the original specs, so I didn't worry about further optimization.

I used K7NV's yagi design (Yagistress) and EZNEC, but you could probably
use a variety of tools to do the same.

Tor
N4OGW

OWA yagi tapering dependency...
 

OWA yagi tapering dependency...
 

Hi Tor, thanks for the help
...it seems to be proven method as I did quick check and
F/B shifted very close to the original and impedance curve was quite ok.
This was very quick as I already had both sw's.
Actual impedance measurements must wait the monster is up probably next summer...

I think you will find they are very easy to build. The only adjustment
that might be needed is the tip lengths on the driven length, which might
vary somewhat depending on the lead lengths on your balun. But I found on
mine (I built two 6 el/21 Mhz and one 6 el/28 Mhz) that I didn't need to
adjust anything in the actual antenna. No adjusting matching networks
since they are 50 ohm Z anyway.

I used insulated element brackets, if you use metal plates you might want
account for that.

The one thing I don't particularly like about the designs I used is that
they are hard to side-mount (with a rotator) on a tower, since one element
is very close to the center of the boom. But they seem to perform quite well.

Tor
N4OGW