Now, wireless communication is in the 5G era. As the wireless communication technology grows rapidly, the devices are directly connected to the internet through wireless medium. This device requires high speed communications. In order to fulfill this requirement, researchers have to improve the bandwidth of transmitting and receiving antenna in the existing design. This paper gives the clear view of bandwidth enhancement by using Taconic TLX-9 substrate material of dielectric constant 2.5. With the help of CST Studio Suite Simulation Tool, a rectangular microstrip antenna was designed under the operating frequency of 3.5 GHz using three different substrate materials such as FR 4, Rogers RT 5870, and Taconic TLX-9. To improve the bandwidth, a proximity coupled feeding technique was used in this proposed model. An analysis was performed with this substrate material. This analysis concludes that the Taconic TLX-9 substrate material gives the bandwidth of 593.7 MHz at a return loss of -35dB. The maximum gain of 7.1dB was achieved under 3.5 GHz and also 6.823 was obtained under 3.5 GHz. The proposed antenna design can be used for 5G application (mid band). Further, the bandwidth, gain, directivity, return loss can be improved by introducing parasitic elements, arrays, SIW concepts etc.