Abstract: The use of a multi-carrier array can make positional modulation realized in directional and/or distance dependent transmission of information, forming a single bit error rate (BER) pattern null at the specified position and improving the security of physical layer communication. However, the presence of the mismatch between the specified and the actual receiving positions will deteriorate the signal reception performance. Based on the rationale of positional modulation, a regional modulation technique was proposed, being insensitive to the mentioned position error. The regional modulation can make the null width of the BER pattern be adjusted properly to form a communication compromise between security and robustness. Firstly, the one-dimensional Woodward-Lawson synthesis method was extended to realize two-dimensional angle-distance flat-top beam pattern synthesis, focusing the energy of the transmitted signal in a preset region. Then, the multi-carrier array manifold vector was constructed, corresponding to the angle and distance selected in the Woodward-Lawson synthesis method. Finally, a vector was randomly selected from the orthogonal complement of the space spanned by the above manifold vectors to encrypt the non-signal energy focusing region. Simulation results show that the regional modulation technique can fulfill a good signal reception performance in the whole preset angle and distance region.