Here is a modular vertical antenna design that several dozen hams have built since I completed the plans recently. The design uses an elevated feedpoint and an elevated radial, so the antenna is similar to a vertical dipole. A Loading coil is used just above the feedpoint, and the single radial becomes a part of the radiating system.
This antenna is very efficient. It works well on any band from 10 Meters through 80 Meters. Parts are available at most do-it-yourself stores. Radio Shack has the wire and some of the connectors. Buddipole.com sells a 9' whip that works perfectly for this design.