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In this Letter, a mu-negative metamaterial (MTM) filter-based novel decoupling technique is presented for multiple input multiple output (MIMO) antennas. The design process has been described in a systematic manner, starting with the basic two port monopole antenna and then adding cancellation network and finally the proposed MIMO antenna by adding the matching network. Since the presented decoupling network is developed using MTM structure, good isolation between the antennas is achieved by maintaining compactness. The presented isolation technique can be used in different applications like in developing circularly polarized and multi-band MIMO antennas. As an example, two port circularly polarised MIMO antenna design is also presented. The proposed designs have been fabricated and the simulation results are experimentally verified.

This Letter explains the design and development of a wideband circularly polarised (CP) antenna based on composite metamaterial (MTM) structures which are applicable for use in small satellite applications. The presented antenna is based on a modified co-planar waveguide feeding technique. The proposed antenna unit cell offers compact size due to its MTM property with dimensions of 0.088λ 0 × 0.19λ 0 at 2.4 GHz. The CP radiation is obtained by placing two composite right/left-handed transmission line unit cells orthogonally and exciting two orthogonally-polarised modes simultaneously. A new 4 × 4 unit cell artificial magnetic conductor metasurface is designed with a compact size at the same operating frequency of MTM-based CP antenna as a ground plane for the proposed antenna, which is found to be increased bandwidth, improved gain, and wider axial ratio bandwidth without altering the antenna compactness. The final antenna obtains an overall dimension of 0.37λ 0 × 0.37λ 0 × 0.18λ 0 at 2.5 GHz. The measured result shows a wider impedance bandwidth of 860 MHz (33.07%), improved axial ratio bandwidth of 410 MHz (15.92%), and a good gain of 5.76 dBic is obtained which are adequate for the use in modern small satellite applications.