The design of the multijunction grill to be used in current drive experiments calls for the optimization of three important parameters: the phase shift Δø between adjacent waveguides, the length of the multijunction grill Lg (from the junction to the mouth) and the surface density n0. This has been demonstrated both analytically and numerically by the results obtained for the four-waveguide grill designed for a small tokamak. It has been shown that the current drive efficiency (or the directivity) can reach 50% for practically arbitrary δø (≠ 0°, 180°), if Lg is properly chosen. The enhanced current drive efficiency at Δø ≠ 90° follows from an uneven power distribution among the separate waveguides and from the self-adaptive adjustment of the phases of the incident waves. The risk of power overloading of the waveguides increases with decreasing n0. A short description of the author's variant of the theory of wave diffraction on the junction is also given. Good agreement between the simple analytic model and the numerical solutions is demonstrated.