I agree with eagle's perfect idea. However, the co-phase setup that Grim is talking about, is typically far from perfect at best. For one thing, if you had a co-phase setup installed with everything as perfect as possible, you would still have some increased loss...due to transformation by the harness, and a very low starting impedance at the antennas. IMO, this would tend to minimize any improved gain advantage that others have noted. I didn't fully understand Grim's analogy earlier using three meters, but if I had understood, I would probably disagree...even without my having tested such a setup myself. Maybe Grim would describe for us what he did with a little more detail? IMO, theoretically a well designed and installed co-phase setup should produce similar results, as some described here. There may be some improved gain in one direction, but the process also adds more loss with the co-phase type system. This tends to equalize results...as compared to a single antenna that is also designed and installed well.