A simple method to estimate mutual interaction of nearest neighbors in a compact planar array

In a planar array mutual interaction between neighboring radiators is more important when nearest neighbors are in contact or nearly so. Since it then becomes greatest at long wavelengths, a particular radiator shape has a limited effect on this maximum interaction. The method proposed consists of investigating the transient field which results on an annular piston of radial width 2a from an impulsive velocity Vδ(t) of the contiguous inner circular piston of radius a. Investigation is facilitated by the exact expressions derived for pressure and force in a straightforward manner. Mutual impedance is also deduced and the results are compared to previous works on different cases.