Here is some data on a 2M vertical polarized antenna I built this week. I'm not sure about the gain but the front to back ratio is very good and conforms to the model. Using the local repeater as a signal source I measured the F/B ratio using an ICOM IC-746PRO. With the attenuator active the reading is S5+ and with the antenna rotated around the reading is not registering on the S meter. I made the antenna out of 1/2" PVC and #6 copper ground wire. I also made a 10M Moxon out of PVC and wire. Haven't got it installed yet. When I install it this week and have some data, I'll send you pictures etc.
Antenna pattern - Blue trace is the design @ 146 Mhz and Red trace is at the upper limit of 148 Mhz.
Gain and SWR plots.
Diagram of antenna.