This study introduces a novel planar monopole antenna designed to operate across three distinct frequency bands for wireless communication applications. The antenna is constructed on a 38 x 38 mm² epoxy substrate made of heat-resistant (FR-4) material. Its design effectively mitigates interference arising from Wi-MAX (3.3 GHz - 3.7 GHz), WLAN (5 GHz - 6 GHz), and the X-band satellite communication uplink band (7.9 GHz - 8.4 GHz). To achieve band rejection characteristics, three slots are strategically integrated into the radiating element. The antenna design is fine-tuned through electromagnetic simulation using Ansoft HFSS software. Subsequently, a physical prototype of the antenna is manufactured and tested. The antenna's operational bandwidth spans from 3.1 GHz to over 11 GHz, exhibiting excellent radiation properties. Both simulated and measured results affirm the suitability of the proposed antenna for portable devices.