VHF Co Phasing

[Se7en]

Has anyone tried Co Phasing two VHF antennas mobile?

If one wanted to experiment on this, what would be needed? How far apart must two "unity gain" antennas need to be to produce some directional gain with out sacrificing height....?

 

[Beetle]

Same as for HF; however, everything will have to be scaled to the frequency.

Experiment. Learn from it. That's what an amateur radio license is for.