No abstract

No abstract

Circularly polarised (CP) orbital angular momentum (OAM) antennas using aperture‐coupled uniform circular array (UCA) are proposed to avoid the polarisation mismatch during the mobility and/or the space communications. A comprehensive derivation for ideal CP UCA is derived and numerical simulations are performed for further analysis. To validate the theoretical result and explore explicitly, the proposed prototype for ±1, ±2 mode OAM antennas with right‐hand and left‐hand circular polarisations are proposed and fabricated with measurements conducted, respectively. Measured radiation patterns, axial ratio versus elevation angle θ and the helical phase wavefronts are all favourable and exhibited. The transmission characteristics versus frequency f, relative azimuthal angel Δϕ and distance D are all measured and analysed, which shows high isolations between different channels.

Both single‐/dual‐bandpass wide stopband filters with rotational symmetry using composite right/left‐handed resonators are proposed in this study. Designs of this type obtain a single passband at 2.40 GHz as well as dual passbands at 2.40 and 5.20 GHz, and achieve a wide stopband with no additional structures, which are implemented and demonstrated with full‐wave simulations and measurements. Standing wave coupling models are presented to analyze the characteristics of a wide stopband effectively. The proposed single‐bandpass filter (BPF) with rotational symmetry achieves a preferable wide stopband, in which |S21| is mainly <−20 dB below 19.00 GHz; the proposed dual‐BPF also obtains a wide stopband, in which |S21| < −20 dB below 16.90 GHz. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:49–53, 2017

No abstract