Multi-resonant microstrip patch antennas have become the most research topics and important technologies in the modern wireless communication systems. To adapt with the contemporary and future technology demands from user end and industries, different communication standards have to be dealt simultaneously with a single wireless device. Therefore, there is a need of either multiple antennas with a single frequency band or single antenna system to support multiple frequencies in wireless communication systems. One of the investigated antennas is a rectangular shaped tri-band antenna with two open square-loop slots and two arc slots loading on radiating patch and modified/defected ground plane has been proposed, designed and fabricated to ensure its functionality in WLAN/WiMAX bands. Another type of designed antenna is slotline loaded circular shaped microstrip planar antenna with meandered-stripline feed structure. The antenna performance and communication quality in terms of bandwidth, radiation and gain, the proposed dual-band planar antenna comply with the requirements from UHF RFID and WiMAX/WLAN applications.
