The Cobweb HF antenna - 5 bands, no ATU, full performance
The Cobweb is a 5-band antenna that is really suited for space retricted QTH's.
in my case it's used for portable work. i have used it at home with good
results, mounted on a 8 meter grounded steel pipe.
My version is made up of a homebrew center hub and 5 fishing poles,
each ~2 meters long. i have then threaded the antenna elements thru
rings to hold them in place on the rods.
The rings are made from curtain
hangers glued with epoxy to the rods. Each elemement is in fact a full
dipole, cut for each of the operating bands.
My version resonates on 10-12-15-17-20 meters.
It's a great antenna, for portable og home QTH use.
Theres a wealth of info on the web about this cool antenna, and the
best i found, which i used for my own cobweb, comes from Steve
in the UK, click his callsign to get some ideas. G3TXQ
Here's the 4:1 balun at the feedpoint. The impedance on the 5 dipoles
will drop as the elements are bend into a square, so you end up with
~12 ohms at the feedpoint. The balun will make that into 48 ohms.
It's actually 2 cores on top of each other, and 2 seperate baluns
in parallel. You will find the complete instructions at the link above.