Isolation enhancement of two closely spaced planar monopole antennas for industrial, scientific, and medical applications

This paper presents a simple yet very effective decoupling mechanism based on the insertion of two adjacent planar monopole rectangular patch antennas separated by λ_o/62. The array achieves a total realized gain of 3.48 dB (exciting one port) and 4.78 dB (exciting two ports), a relative bandwidth of 49 % ( 2 - 3.3 ) GHz over which the matching level |S₂₁| is less than -10 dB and a coupling level |S₂₁| is below or equal to -20 dB. The antenna array offers radiation pattern diversity for different port excitation situation. The gain, decoupling level, radiation pattern diversity, and relatively compact size offered by the proposed antenna provides a good candidate to be implemented in modern wireless communication devices including, but not limited to, systems utilizing the ISM band.