I am finishing my MININEC modeling of a close-spaced 2el 80m Yagi. 68 foot
inductor loaded elements, 28 foot boom. Reflector/driven configuration.
These dimensions have been selected to fit on my small lot.
So far the modeling looks promising with reasonable F/B, good gain but, as
expected, very narrow bandwidth......both SWR and F/B. My inductor design will
be 1/4" copper tubing on a 6" "almost air" core. (need around 30 uh and the
losses should be manageable).
I am looking for some advice on matching alternatives...Coiled Hairpin, T,
Gamma/Omega ?? The modeled feedpoint impedance is around 16 ohms (at 100' ).
With the narrow bandwidth, I need to be able to remotely tune the feed....at
least for CW/SSB. (The reflector will also be remotely tuned..probably relay
selected capacitors.)
At this point I imagine a split element, but realize a good balun would be
required in this case. Maybe an Omega match with remote motor-drive Caps would
make band tuning easier. The F-12 coiled hairpin seems like a good alternative,
but then would require a inductor type switch box for band tuning.
Anyone have some ideas or real-time experience with this??
Thanks, de Steve VE6WZ
--- StripMime Report -- processed MIME parts ---
multipart/alternative
text/plain (text body -- kept)
text/html
---
|