In this paper a millimeter wave (mm wave) with rectangular shaped slot antenna is implemented at the operating frequency of 28 GHz to improve the efficiency of 5G networks using micro strip technique for feeding. The main objective of utilizing slot is to enhance the antenna performance in terms of gain, directivity, bandwidth, efficiency, radiated power and accepted power. Rectangular slot antenna of required frequency bandwidth is utilized in the proposed model. Additionally to enhance antenna gain Frequency Selective Surface (FSS) is deployed which is designed using the similar fundamental mode of antenna and located at particular distance to attain desired gain improvement with appropriate dimension of 25 x 25 x 5 𝑚𝑚3. By incorporating FSS into mm wave rectangular antenna ensures 6.7 dBi of gain improvement and S11 ≤ −10 dB from 26 GHz to 29.8 GHz of bandwidth enhancement with improved radiation efficiency which are obtained from tested and experimental data. These results attained using proposed antenna are subsequently better when compared to existing antenna system. Thus, the proposed antenna with high gain efficiency makes it more suitable for 5G wireless communication applications.