Articles written in Sadhana

    • Cylindrical air spaced high gain dielectric resonator antenna for ultra-wideband applications


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      A new geometry of ultra-wideband (UWB) hollow dielectric resonator antenna (DRA) has been designed, simulated, and fabricated. The antenna consists of a rectangular dielectric resonator and excited by a transformer type microstrip feedline. A hollow cylindrical-shaped structure is extracted from a rectangular DR to improve the gain and impedance bandwidth of the antenna. The present work shows that the shifting within the UWB range along with the gain enhancement is observed by increased diameter of the hollow structure and the use of defective ground structure in the ground plane. The antenna provides four different radiating modes, namely TE11d at 3.8 GHz, TE22d at 6.4 GHz, TE231Z at 8.8 GHz, and TE33d at 10 GHz that support to give widen impedance bandwidth. The simulated and measured results are in good agreement as an impedance bandwidth of 104.09% (3.28 to 10.4 GHz) and 103.86% along with a peak gain of 7.2 dB.

    • Broadband circularly polarized dielectric resonator antenna for UWB applications


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      In this paper, a compact circularly polarized asymmetric dielectric resonator antenna (DRA) excited by a quarter-wave transformer (QWT) feedline is proposed for ultra-wideband (UWB) applications. The DRA consists of two rectangular ceramic blocks with the same permittivity (εDR = 9.8) and an F-shaped metallic strip combined with the partial ground. The proposed antenna is supported first and third-order modes as TEδ11 and TEδ13 at 9.1 and 11.28 GHz. The proposed antenna covers ultra-wideband (UWB) range from 6.4 to 12.4 GHz (impedance bandwidth of 63.8 %) with a peak gain of 6.01 dBi at 11.5 GHz. The broad AR bandwidth of the proposed antenna is achieved by the asymmetric structure of DR and the modified ground. The simulated AR bandwidth (≤ 3 dB) of the proposed antenna is 63.8% (6.4 to 12.4 GHz), and the measured AR bandwidth is 2.5% (5.8 to 6.1 GHz) and 43.7% (6.9 to 10.9 GHz). The proposed antenna can be used for C, X band applications.

    • A miniaturized highly isolated double negative metasurface MIMO antenna for sub-6GHz band


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      This paper presents a double negative (DNG) metasurface-based multiple input multiple output (MIMO) antenna with a wideband operation for the sub6-GHz range of 5G communication. The MIMO antenna (called DNG-MIMO antenna) consists of two DNG metasurface antenna elements placed closely on a partialground with a U-shaped slot. The proposed DNG-MIMO antenna has a compact size of 20.5 mm X 40 mm with an operational bandwidth of 1500 MHz (4.9 GHz–6.4 GHz) and a peak gain of 3.49 dB. With a minimal interelement distance (0.18 λ, where λ is operating wavelength), the DNG-MIMO antenna exhibits very highisolation (s12<-25.5 dB) for the entire resonating bandwidth. The proposed DNG-MIMO antenna exhibits good MIMO performance metrics such as envelope correlation coefficient (ECC<0.003), diversity gain (DG = 10 dB), total active reflection coefficient (TARC<-10 dB), and channel capacity loss (CCL<0.3 bits/Hz/Sec). The total efficiency of the DNG-MIMO antenna is more than 80% across the operating bandwidth. Thus, with a miniaturized dimension, good MIMO performance metrics, and wide bandwidth, the proposed metasurface MIMO antenna is ideal for the upcoming 5G communication systems and various IoT applications. For analysing the practical applications of the proposed MIMO antenna, an 8-element DNG-MIMO is connected to an extended ground plane, the results obtained suggest no deterioration in s-parameters, efficiency, ECC and DG is observed.

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