Frequency Reconfigurable MIMO Antenna using SRR for Multi-Band Operation

This work presents the design of a 4-element frequency reconligurable multiple-input-multiple-output (MIMO) antenna. The individual element is comprised of modified annular slot antenna using split-ring resonator(SRR) loading and a rectangular slot inside the annular slot to achieve miniaturization and multi-band operation. Each slot element is loaded with a varactor diode which provides the frequency sweep in each of its operating bands. The proposed design operates in three bands covering 1.7-2.28 GHz, 2.5-2.85 GHz and 2.9-3.1 GHz bands. The antenna is designed on a standard Rogers 4350 substrate size of 60x 120x 0.76 mm(3). A prototype is fabricated whose measured results are in close agreement with the design simulations. The antenna is also analyzed for envelope correlation coefficient (ECC) where it shows an ECC < 0.5 in all of its operating bands, signifying good MIMO performance. The proposed design is suitable for second generation cognitive radio applications.