5 Jul 2015
2 big wheels, suitably stacked, should give about 5dBd gain horizontal and need no turning. This is not far off the gain from my 5el yagi in the best direction. Quite often I work stations off the direction of maximum gain. For my kind of operation (mainly UKAC contests and beacon monitoring) I think a big wheel is well suited.
70cm big wheel stacks are a lot smaller than the 2m versions. The stacking distance is smaller too. Commercial big wheels are available from Wimo in Germany.
See http://www.wimo.de/big-wheel-antennas_e.html .