See
http://www.w5dxp.com/rotdip.htmWhich describes about the simplest multi-band rotatable antenna you can build. Another simple multiband antenna is an "8JK" invented by John Kraus
W8JK and consists (in its simplest form) of two dipoles fed with open wire line with an interconnecting phasing line. You can find it described in almost any
age ARRL Antenna Book.
Good luck Allen