Compact modified 'T' slot circular patch quad band antenna for MIMO applications

Compact modified T-slot circular patch antenna for multiple input multiple output (MIMO) applications, which has good response for four operating frequency bands is developed. Here the design consists of a circular patch with a new slot loaded T-shape on one side of the substrate and a feeder line on the other side of the substrate. A shorting pin is located between the patch and the feeder line. This proposed antenna resonates at the frequencies of 2, 4.8, 5.4, and 6.2 GHz covering the S-band, C-band, and LTE applications. The independent tuning of frequency bands is achieved by varying the length of the slots. By independent tuning of frequency bands, the selection of interested frequency band is achieved. The single element with miniaturized size of 1.945 lambda x 1.945 lambda (30 x 30 mm(2)) is achieved including the feed line. The antenna has been tested for MIMO applications. The measured envelope correlation coefficient between the two elements, which are spaced 0.139 lambda is < 0.1(low correlation) and mutual coupling is found to be in the range of -20 dB to -80 dB. The simulation and measurement results of reflection coefficient, mutual coupling, and radiation pattern are presented.