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.
In this study, to design a compact four‐port multiple‐input–multiple‐output (MIMO) antenna for dual‐band wireless local area network applications, both frequency and isolation between antennas are made as reconfigurable. Both antenna element and decoupling network shown in this study are designed using meander line concept. The frequency reconfigurable capability of the antenna is achieved by incorporating positive‐intrinsic‐negative (PIN) diodes in the meander line resonator. By making PIN diodes ON and OFF, four antenna elements switch their operating frequency in between 2.4–2.5 and 5.1–5.8 GHz bands. Isolation between the antenna elements also made as reconfigurable by placing PIN diodes in the decoupling network. In ON state, isolation is found in 2.4–2.5 GHz band, whereas in OFF state, isolation is achieved in 5.1–5.8 GHz band. Overall, in both the bands, excellent isolation (more than 15 dB) between the antenna elements has been achieved. The proposed antenna design is printed on the FR‐4 substrate and its overall area is 38 × 38 mm2. Each antenna element is in polarisation diversity with the adjacent antenna element which makes the proposed design suitable for achieving good MIMO performance.
In this paper, the design, fabrication, and measurement of a high-performance metamaterial absorber (MMA) have been presented. The three major concerns of MMA's are narrow bandwidth, angle sensitivity, and uncontrollable polarization. By smartly controlling the proposed design, the solutions to these three concerns of MMA are given in this paper. By integrating the design with varactor diodes, we make the MMA tunable to wide frequency ranges. Frequency tunability ranges from 4.2 to 7 GHz. By using circular sectors in the resonator, wide incident angle insensitivity has been achieved. The presented MMA exhibits more than 80% absorptivity up to 70° incident angles. With the proposed design, it is possible to control either TM or TE polarization resonant frequency by fixing the resonant frequency of other polarization. Also, a biasing technique which is simple and effective to control both TM and TE resonant frequencies simultaneously is given in this paper. Moreover, all these advantages have been achieved by using a single layer low cost FR4 material having thickness 0.6 mm as a substrate. By using a standard parameter retrieval technique, the real and imaginary parts of both permittivity and permeability of the presented MMA are calculated. It is expected that the presented work improves the state-of-the-art in the smart metamaterial absorber domain.
This Letter demonstrates design, simulation, fabrication and performance of a metamaterial (MTM) absorber having wide incident angle insensitivity for conformal applications in X-band region. The important feature of the proposed structure is achieving more than 90% absorptivity with very low thickness. In this design, an FR4 material having thickness 0.1 mm is used as a substrate. Hence, the overall thickness of the proposed MTM absorber is only 1/81 of the wavelength at the resonance frequency of 9.2 GHz. Also, the presented absorber is offering more than 80% absorptivity up to 50°incident angle which is very much suitable for conformal applications where curved surfaces are involved. Designed MTM absorber has been fabricated and simulation results are experimentally verified.
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