Recently, the field of wireless communication is the most widely researched area and the study of the communication system is incomplete without knowing the operation and the use of different types of antenna. The study of microstrip patch antennas has made great progress in recent years. Compared with conventional antennas, microstrip patch antennas have more advantages and better prospects. They are lighter in weight, low volume, low cost, low profile, smaller in dimension and ease of fabrication and conformity. Moreover, the microstrip patch antennas can provide dual and circular polarizations, dual-frequency operation, frequency agility, broad bandwidth, feed line flexibility, beam scanning Omni directional patterning. Hence a Comparative study of circular microstrip-fed patch antennas for blue tooth application is presented in this project. The resonance frequency is chosen at 2.45 GHz which is suitable for industrial scientific and medical (ISM) band applications. HFSS is used as the software environment to design and compare the performance of the antennas with and without slot.