Are you looking for a cp or linear microstrip? Cavity backed or thin?
The thinner you are required to be the less (as a general rule) bandwidth you will get.
look into log elements, shorted patch elements, printed spirals, vivaldi elements (a number of simulation mfg's have used vivaldi antennas as benchmarks). If you don't need all the bandwith all the time you could look into active switching for tuning.
Your request is pretty vague but I hope this helps.
H3O