In this research paper, a compact rectangular multiband monopole antenna with mender-shaped slot is presented suitable for UMTS/WLAN/WiMAX/Long-distance Radio Telecommunication applications. The slot in the rectangular patch provides three bands with better gain and increased radiation pattern. The propose antenna size is 42x35x1.6 mm3. This antenna gives the frequencies ranging from (1.9-2.4)/2.1 GHz, (6.3-7)/6.6 GHz and (8.4-9.8)/9.1 GHz suitable for DECT/PHS, UMTS, WLAN, WiMAX, Long-distance Radio Telecommunication and Satellite Communication applications with the return loss of -26 dB, -40 dB and -24 dB and gain 3 dBi, 5 dBi and 2.2 dBi respectively. This compact antenna is fabricated using the low cost FR4 substrate with dielectric constant of 4.4 and 0.02 loss tangent. The return loss and radiation pattern for this antenna is simulated on ANSYS HFSS.