Hello Tumpa Sarker ,

The simplest answer is to use CST full version. Even with the proper version, for intricate designs, meshcell size may cross 10M-20M, especially for intricate antenna and microwave devices. You will require 12-24GB RAM to accommodate such a higher size and to speed-up the simulation, you can use CPU acceleration by increasing the number of cores used for your simulation in "Setup Solver>>Acceleration".