Most widely used antenna for indoor and outdoor wireless communication applications is the microstrip antenna but one of the drawbacks is the low bandwidth. The wireless communications demand the patch antenna with large bandwidth, low cost and small size. The microstrip patch antenna fulfills all requirements except the large bandwidth. In this paper, the design and development of RMSA for ultra-wide-band wireless communication applications is presented. Modified patch antenna geometry is a dome shape at the top and symmetrical dual steps at the bottom corners of rectangular patch at one side and the other side is finite partial ground plane with rectangular notch at the center. The antenna presented in this study is simple in design and enhances the bandwidth from 2.43% (2.04–2.91 GHz) to 163% (1.23–12.02 GHz) which is 67 times larger than the conventional RMSA bandwidth. The presented antenna can be used in many wireless communications such as, GSM, DBB-H, UMTS, GPS IMS, Wi-Fi/WLAN, ITU, etc. The maximum gain obtained is 3.75 dB. Nearly omnidirectional radiation patterns are observed. HFSS software is used for simulation and experimental work is carried out using VNA “Rohde and Schwarz, Germany make ZVK model 1127.8651” 10 MHz–40 GHz. The modified proposed microstrip antenna finds potential applications in current UWB communication system.