Diversity-based four-port multiple input multiple output antenna loaded with interdigital structure for high isolation

Author:

Ramachandran, Anitha  Mathew, Sumitha  Viswanathan, Vinesh P.  Pezholil, Mohanan  Kesavath, Vasudevan  

Journal:

IET MICROWAVES ANTENNAS & PROPAGATION

Issue Date:

2016

Abstract(summary):

A four-port planar multiple input multiple output antenna system employing polarisation and pattern diversity technique is proposed. The antenna system, resonating at 2.4 GHz ISM band, includes a dual polarised two-port cross-patch antenna and an orthogonally polarised two-port square ring patch antenna. Undesired high coupling between elements is reduced by incorporating an interdigital structure on the ground. This reduces coupling between elements by 12.5 dB, ensuring a high isolation of about 28 dB between any set of elements in the antenna system. The overall size of the quad element antenna is about 0.5 x 0.5, which makes it fairly compact. The cross-patch antenna has low cross-polarisation levels, which reduces the coupling between its orthogonal elements. The narrow bandwidth of the higher order modes of the square ring antenna is doubled by adding half wavelength slits along its arms. All four elements have a 2:1 voltage standing wave ratio (VSWR) bandwidth of 85 MHz and have low envelope correlation in the operating band. The antenna is printed on a low cost FR4 substrate and does not require any intricate fabrication.

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