I was saying smaller than the argive shield represented in the picture. The shield carried by the Macedonian phalanx, presumably, carried an even smaller shield than the so-called Iphikratean hoplitai, (reformed hoplite as Unramma calls it), or at least not bigger than that which they used.

An argive shield weights something like 8 kg and about 1m across.....I think thats too much weight and diameter to strap it on your forearm, even with the help of neck straps (which are not represented in your pic), although I haven´t used one personally, so I´m just guessing.