Design of Combined UWB and MIMO UWB Antenna for Mobile Terminals

In recent wireless communication systems, Ultra-wideband (UWB) techniques are the research hotspot for their inherit advantages, such as: low-power, high data rate in a limited range and easy fabrication. Achieving ultra-wideband characteristics with preserving the compactness of the structure is highly demanded in printed patch antennas. MIMO technology provides the multipath propagations, offering spatial diversity for the best signal reception. A 3-port complementary and Slot combined antenna is proposed with one port operating at UWB and other two ports at upper wimax band ranging from 5.2 to 7.5GHZ frequency. Simulations and measurements showed that the use of corrugation increases the bandwidth of the slot structure. The front radiating patch structure is a complementary bow-tie antenna and the two bow-tie slots are excited at the back through micro strip line rounded at its edges. The Complementary structure produces a bandwidth of 120% and each single bow arm slots produces 36% bandwidth. Mutual coupling coefficient between the ports is lesser than -10 dB throughout the operating band. Design considerations for the front and back radiating structure are extensively discussed.