Design and development of triple-band compact ACS-fed MIMO antenna for 2.4/3.5/5 GHz WLAN/WiMAX applications

In this paper, a very small size (20 x 14.75 mm(2)) triple-band multiple-input multiple-output (MIMO) microstrip patch antenna for WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5 GHz) wireless applications. The goal of this paper is to merge these two wireless standards into a single antenna that can be easily accommodated inside the devices operating in three different frequency ranges. The proposed MIMO antenna consists of an asymmetric coplanar strip (ACS) feedline loaded with an inverted L-shaped slot and a meanderline. The inverted L-shaped slot and the meanderline both having an electrical length 0.5 lambda, are responsible for the achieving the operating band around 3.5 and 2.4 GHz, respectively whereas the ACS feedline is responsible for the generation of 5 GHz frequency band. The fabricated prototype of the proposed MIMO antenna when tested, shows three distinct frequency bands; I from 2.38 to 3.00 GHz, II from 3.21 to 3.61 GHz and III from 5.02 to 6.18 GHz that covers entire frequency bands of WLAN and WiMAX wireless applications along with different standards of IEEE 802.11 including a/b/j/p/g/n/ac/ax. The peak gain in I, II and III frequency bands is 7.93, 4.23 and 7.57 dBi, respectively. In addition, the diversity performance in terms of envelope correlation coefficient, diversity gain, multiplexing efficiency, total active reflection coefficient, and mean effective gain is also performed for the proposed MIMO antenna.