Hi Samudra,

Phased array is a generic term. Stacked yagi's are a phased array :) If you mean electrically steered phased arrays, that's another story. If you mean non-steered phase arrays, that is also another story. As far as I know there has not been much work in the amateur community on electrically steered arrays. For that matter they are not that common in the commercial world either. Even the current Ku/Ka band antenna's used on commercial aircraft for inflight Internet use mechanically steered antenna's. If you meant an array of patches to produce a flat panel antenna that had less mass than a yagi, these are really only practical at frequencies higher than UHF considering the gain to patch area ratio.

Howie AB2S