The primary surveillance radars and secondary surveillance radars in airport applications are generally located in complex environments. Most of the times the airports are located near the mountain regions. These complex environments will have a greater impact on the vertical coverage area. The transmitting frequency, atmospheric attenuation, surface roughness and radar cross section area are the important parameters that alter the radiation pattern characteristics. The objective of the project is to design and compare simultaneous Multi - beams under complex environments. The objective is accomplished by using a planar array to implement different beam patterns (Pencil beam, Fan beam and Intermediate beam) to have a required coverage area. The variations in the vertical coverage area as a function of transmitting frequency, attenuation, surface roughness, variation in reflection coefficient of the earth surface and radar cross section is also analyzed in this project. The objective of this project is achieved making use of MATLAB software.