I wanted an aerial for portable use, so I thought I’d try a kit from Sotabeams, called a Linked Dipole Kit.
It contains all of the pieces to allow you to make up a multi-band dipole, using crocodile clips to connect together the sections of the elements, tuning for different bands.
I made mine for 17m, 20m and 40m. Putting it on the air, with a lightweight fishing pole as a mast, it worked pretty well.
The kit can be bought from here
You can listen to my feature on this aerial on the ICQPodcast here.