In this paper, an angular symmetric, common radiator coplanar waveguide (CPW) fed four-port multiple-inputmultiple-output (MIMO) antenna is designed on a 0.129λ L 2 RT Duroid (ε r =3.0, tanδ=0.001) substrate where λ L is the free space wavelength at the lowest operating frequency (f L ) of 0.6 GHz. The antenna has a -6 dB impedance bandwidth from 0.6-1.09 GHz, 2.6-3.4 GHz and 4.2-7.0 GHz to cover the emerging wireless communication bands. At the same time, it also has a -10 dB impedance bandwidth extending from 0.7-1.01 GHz, 2.6-3.18 GHz, 5.3-6.06 GHz, and 6.7-6.94 GHz. Design steps to enhance the operating bandwidth and the isolation in the sub-1GHz bands are presented. The antenna has a reasonable realized gain at the simulated and measured frequencies. It exhibits the pattern diversity which is useful for the MIMO implementation. The envelope correlation coefficient (ECC), Mean effective gain (MEG), and the channel capacity of the antenna have been computed from the measured results. In spite of the small circuit size at f L , the ECC 0.50 over the entire band is observed. In addition to the existing communication applications, this antenna can find newer applications in the emerging 0.6-1.09 GHz band, sub-6GHz 5G near radio (NR), and Wi-Fi 6 communications.
This article presents the design of a wideband bandpass frequency-selective surface (FSS). The structure is designed using the analysis of the generalized scattering matrix (GSM)-based transmission phase range. A relationship between the transmission phase range and the bandpass fractional bandwidth (FBW) is developed. The analysis reveals that the FBW of the FSS unit-cell is proportional to the phase range. Based on the interpretation of results, a design curve has been drawn, and using this curve, a simple square slot FSS on a low-cost FR-4 substrate has been fabricated and measured. Using the design curve, a 53% FBW has been predicted. The simulated results show a 52% FBW with the 3.52-GHz center frequency (f o ). The response for the transverse electric (TE) and transverse magnetic (TM) modes has been measured. The structure has a bandpass FBW equal to 50% and 53.3% in TE and TM modes, respectively. The method presented in this article may be used to increase the bandpass response of different FSS topologies.
K E Y W O R D Sbandwidth, frequency-selective surface, generalized scattering matrix, passband, phase rangeThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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