ON PERFORMANCE OF HIGH-EFFICIENCY FERRITE MEANDER ANTENNA (HEMA) FOR MIMO COMMUNICATIONS

This paper presents a high-efficiency ferrite meander antenna (HEMA), which can be used to realize a 2 x 2 multiple-input-multiple-output (MIMO) communication system when it is used at both the transmitter and the receiver ends. This antenna is designed to operate at 2.45 GHz center frequency ([f.sub.c]). It consists of two spatially separated half-cycle microstrip meander structures. Ferrite material is not used for the entire substrate, only beneath each meander structure. A standard FR-4 substrate is utilized as a system board. Impedance bandwidth and radiation patterns of the fabricated antenna are measured and compared with those of the simulation results. The -10 dB impedance bandwidth of the fabricated antenna is 262 MHz, whereas the simulated bandwidth is 235 MHz. According to the simulations, the gain and efficiency of the antenna are 2.2 dB and 81%, respectively. The efficiency of the antenna is confirmed by measurements. By using the simulated radiation patterns, correlation between the radiation patterns is calculated and employed in the generation of the channel matrix. Mutual impedance of the antennas and antenna efficiency are also included in the channel matrix, which in turn is used in bit error rate (BER) and ergodic capacity simulations. BER and ergodic capacity are utilized as performance metrics. The effect of antenna efficiency, mutual impedance of the antennas, and correlation between radiation patterns on system performance are presented.