Why not a 21.6mm x 21.6mm sensor?

Rriley wrote:

Id dispute the 21.6 dimension, as its actually considerably bigger in the firstplace
originally Kodak had it at 18x13.5 243sqmm
then the spec became 17.3x13 225sqmm
which one of those has a 21.6mm baseline ?

what you have fashioned is a sensor dimensioned on the diagonal of the Panasonic sensor
but you are using it in the horizontal and vertical dimension
I think you mistook ..., the square sensor would have the same baseline as 43rds
unless people want to argue with me over the practicality of using a 20x15 300sqmm 43rds sensor
but Id have to gather up some of the previously stated views first