A low-profile dual port UWB-MIMO/diversity antenna with band rejection ability

Abstract

A band notched ultra-wideband (UWB) antenna is presented in this article as a good prospect for multiple-input multiple-output (MIMO)/diversity application. The proposed MIMO antenna is constituted of two modified rectangle-shaped patch antenna elements. A stepped stub is extended from the modified ground plane as a decoupling element between the radiators to realize a good isolation level between them. A band rejection response is obtained by connecting an open resonant stub to each of the radiators. The simulated prototype is fabricated and tested for verification. Results reveal that the proposed prototype provides a 10 dB return loss bandwidth from 3.08 to 10.98 GHz with band notch characteristics from 4.98 to 5.96 GHz, and a good port isolation level (S 21 20). Diversity performances are ensured in terms of total active reflection coefficient, envelope correlation coefficient (<0.013 except notch band), diversity gain (%9.51 dB), mean effective gain ratio (%1), and channel capacity loss ( 0.35 bps/HZ except notch band). It evidences that the presented band notched UWB antenna can be a good prospective for MIMO/diversity applications. K E Y W O R D Schannel capacity loss, diversity gain, envelope correlation coefficient, mean effective gain, MIMO, ultrawideband | I NT ROD UCTI ONMultiple-input multiple-output (MIMO) technology has the capability to ameliorate the performances of the system in multipath fading environment due to its incredible augment in the channel capacity, spectral efficiency, and data throughput of the wireless system. 1,2 Recently ultra-wideband (UWB) technology has also drawn considerable attention in short-range communication system due to its wide frequency range, low cost, enhanced data rate, and low power level. However, conventional UWB systems have endured problems due to multipath propagation which can be resolved by MIMO technology. The combination of these two technologies (UWB-MIMO) can deliver tangible benefits in the scattering environment with high data rate, wide communication range, and enhanced channel capacity, good reliability of the link and suppression of interference. 4-6In various UWB-MIMO systems, in-band EMI can originate due to the co-existence of various narrowband systems, such as wireless local area network (WLAN), Industrial, Scientific and Medical (ISM), radio frequency identification device (RFID), and dedicated short-range communication (DSRC) systems, those operate in the range 5.1-5.925 GHz. Therefore, it is essential to develop an adequate MIMO antenna with band notch ability to extenuate this interference. In practice, many band notch techniques are available in the literature. Some of them are integrating slot on the ground plane or radiator, 7 using stub attached to the radiator/ feed line, 8 CSRR on the radiator, using EBG structures, 9 placing parasitic elements adjacent to the radiator. 10 Nevertheless, by applying these traditional band notch techniques directly to the UWB-MIMO antenna, it will strongly affect the isolation level of the ...

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