A single-cell tri-band composite right/left-handed (CRLH) resonant antenna is presented. The antenna is designed on a single-layer coplanar waveguide-fed based on the T-junction discontinuity equivalent circuit. The proposed antenna provides compact size, easy fabrication process, multi-band feature and higher efficiency in comparison with the previously reported CRLH resonant antennas. The single-cell CRLH resonant antenna is fabricated and the measurements are consistent with the simulation result.
A new asymmetrical zeroth-order resonant antenna with improved efficiency and widened impedance bandwidth is proposed. It comprises a rectangular patch, two shorted stubs and a coplanar waveguide feed to have composite right/left-handed features and an easy fabrication process. The asymmetry helps to combine three resonance frequencies and extends the bandwidth up to 61.6%. The efficiency of the proposed antenna is >85% over the entire bandwidth of 4.41-8.34 GHz. The proposed antenna has a compact size, which can provide an omnidirectional radiation pattern suitable for wireless applications. These features are verified by CST Microwave Studio and compared with the experimental results.
An analytical model is presented to determine the perantenna power distribution of a beamformed M-element uniform linear array (ULA) as a base station antenna (BSA). The analysis assumes a single sector cell serving two user equipments (UEs) in a downlink multiuser multiple-input multiple-output (MU-MIMO) system employing zeroforcing (ZF) transmission. Determinative design parameters of the BSA configuration are identified. Afterwards, their effects on the power spread across the array are investigated when the positions of the users are random and they are uniformly distributed over the cell. It is shown that the power distribution across the ULA antenna aperture is a periodic function whose characteristics mainly depend on the angular separation of two UEs and the number of BSA antenna elements. A significant variation between ULA input powers is seen to occur if the number of elements in the ULA is smaller than one period of this power distribution function. In order to mitigate the dynamic range of the power variation across the array, an upper bound for the inter-element spacing, depending on the field-of-view (FoV) of the BSA, is defined. It is shown that, in a 20-element ULA, increasing the inter-element spacing from 0.5λ to 1.4λ reduces the power variation from 19 dB to 10 dB for differentiating two close-by UEs with 1 • angular separation.
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