Browsing by Author "Saarinen, Tapio O."

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  • Realizing Optimal Current Distributions for Radiation Efficiency in Practical Antennas
    (2020-05) Kormilainen, Riku; Hannula, Jari Matti; Saarinen, Tapio O.; Lehtovuori, Anu; Viikari, Ville
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Modern antenna design is facing increasing issues with the radiation efficiency, since the space available for antennas is scarce and antennas are fitted into lossy environments. This letter presents a multiport antenna design method with a computationally efficient way to realize the port currents providing the highest radiation efficiency. In this method, an antenna is described with multiple excitation ports in electromagnetic simulations. The measurement results of an example design demonstrate the achieved benefit compared to traditional antenna design.
  • Tunable eight-element MIMO antenna based on the antenna cluster concept
    (2019-06-12) Hannula, Jari Matti; Saarinen, Tapio O.; Lehtovuori, Anu; Holopainen, Jari; Viikari, Ville
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Realising capacity demands of future wireless communications require improved spectral efficiency in the sub-6 GHz frequency bands. This study proposes a novel eight-element multiple-input-multiple-output (MIMO) antenna that can be tuned from 1.7 to 6 GHz. The design is based on the antenna cluster concept, where weighted feeding of multiple antenna elements is used to modify the operating frequency. This study extends the theory of the concept to account for multiple separate clusters, thus enabling it to be used for MIMO. The proposed antenna achieves over 60% efficiency at frequencies above 3 GHz, and the system exceeds the ergodic capacity of the ideal 7 × 7 MIMO in that band.