I meditated upon unused empty space at the attic of my house. Started with a simple dipole for 7 Mhz
which fitted the complete length of the attic (20m). It was fed by coax directly running into my shack
which is immediately below - coax length abt. 7 mtrs.
No balun or anything - just soldered both ends to the coax-feeder ;-) This simple dipole worked well
and I abused it with a little help of my versatile Annecke ATU to resonate on 14, 21 and 28 MHz (ooutch ...)
Used it a lot, mostly with my homebuild QRP-TRX on 20mtrs (see photos).
Sometimes I felt that there must have been a little mismatch on the feedline - those days I didnt care ...
Now I know: Never use a 40-mtr dipole for 20-mtr...
Many years passed without using it - as stated on my QRZ-page.
I was too busy with other things, family, profession, education, health...
But Amateur radio got me back !
When I started anew in 2014 first thing I did was trying to figure out how to improve the antenna.
Immediately I got it: a 40mtr dipole will never be resonant on 20 mtr. So I added another, shorter dipole for 20 mtr
to the same center feed. Worked like a charm !
Then I considered the radiation pattern of my dipoles. To south and to north. Good, but could be improved.
So I added one more 20mtr-dipole to the existing one - yes, thats it. Now I had nearly 360 degree characteristic.
Hey, and all this with only one feedline! Great!
So on we go. Next thing is a dipole pair for 30mtr. Great, but no match ;-( SWR too high 3.1.
Okay, what to do? Try a current balun (1:1) and use the ATU. Thats it. Good enough.
Then I thought about naming this simple but efficient antenna system, googled around and found (naturally)
there already is a name for it: it is a multiband FAN-DIPOLE.
Indeed nothing new at all, but I had discovered it by myself - purely by mediating about a practical simple solution - ;-)
This is the center connector with Balun and brass connector for the diole wires...
This rather simple aerial is built of loudspeaker cable.
40m band: 20,2 m
30m band: 14,3 m
20m band: 10,24m
15m band: 3*lambda/2 of 40m
10m band: 5*lambda/2 of 40m
So this construction is indeed a 5 band antenna !