An antenna array lattice design is disclosed, comprising a plurality of column and row members that interconnect using a tongue and groove feature to result in a stable lattice arrangement. Each row and column member comprises a plurality of slots configured to receive corresponding slots of opposing row or column members. The slots have surfaces that run approximately one half the length or width of the associated member. The slot surfaces have recesses machined therein, and the recesses are shaped to accept correspondingly shaped projections of the opposing row or column member. In one embodiment, the recesses are T-shaped, as are the associated projections. The slots acts as a guide for the row to column attachment during assembly, while the precise geometry of the groove design allows both tensile and compressive forces to be carried across the entire depth of the joint, thus maximizing the stiffness/weight ratio of the resulting array lattice structure.