In this paper, a wideband monopole antenna with reconfigurable frequency notch through wireless local area network (WLAN)(5.15-5.35 GHz and 5.725-5.825 GHz) or future wireless fidelity 6GHz (Wi-Fi-6E)(5.925-7.125 GHz) band for C-band applications is presented. The conventional/basic monopole antenna consists of four-leaf clover antenna structure with cascaded feeder and Defected Ground Structure (DGS). The basic antenna is designed and then simulated using Computer Simulation Technology (CST) and High-Frequency Structure Simulator (HFSS) readymade software programs. The antenna covering an operational bandwidth extends from 4.2 GHz to 9.2 GHz while the gain is around 4.0 dBi. Two simple resonator conductors are added near the thin feeder of antenna to realize the notched frequency. The rejected frequency within WLAN or Wi-Fi 6E bands is controlled by the resonator conductor lengths, so Positive-Intrinsic-Negative (PIN) diodes switches are inserted to achieve the required length for each rejected band. Finally, each of the basic antenna and the proposed notched antenna are fabricated and measured. The measurement results are in good agreements with the simulated results of CST and HFSS, providing good antenna performance and sharp notches with good rejection values.