2D Waveguide Mesh

At each junction:

$$\begin{eqnarray*} V_J &=& \frac{\mbox{in}_{1} + \mbox{in}_{2} + \mbox{in}_{3} +... ...}{2} \\ \hbox{out}_k &=& V_J - \mbox{in}_{k}, \qquad k=1,2,3,4 \end{eqnarray*}$$