A printed compact monopole antenna based on a single negative (SNG) metamaterial is proposed for ultra-wideband (UWB) applications. A low-profile, key-shaped structure forms the radiating monopole and is loaded with metamaterial unit cells with negative permittivity and more than 1.5 GHz bandwidth of near-zero refractive index (NZRI) property. The antenna offers a wide bandwidth from 3.08 to 14.1 GHz and an average gain of 4.54 dBi, with a peak gain of 6.12 dBi; this is in contrast to the poor performance when metamaterial is not used. Moreover, the maximum obtained radiation efficiency is 97%. A reasonable agreement between simulation and experiments is realized, demonstrating that the proposed antenna can operate over a wide bandwidth with symmetric split-ring resonator (SSRR) metamaterial structures and compact size of 14.5 × 22 mm2 (0.148 λ0 × 0.226 λ0) with respect to the lowest operating frequency.
This paper studies the effects of incident wave angular power spectrum (APS) distribution and user hand effect on the envelope correlation coefficient (ECC) of a two-port MIMO antenna operating in the sub 6 GHz LTE-U frequency band. APS of uniform and Gaussian distributions are used with different Gaussian angular spread (AS) values, i.e., 10 • , 30 • , 50 • , and 70 •. A prototype was fabricated, and three-dimensional radiation patterns of the antenna elements were measured in an anechoic chamber from 4 to 6 GHz in both cases of free space and when the prototype is held in data mode using a hand phantom. An algorithm to calculate ECC from the complex data of far field radiation pattern with different APS distributions is explained in detail. Results show that user hand presence increases ECC between ports compared with free space, whose increase is more obvious under Gaussian APS. ECC values under uniform APS is practically zero over the entire frequency range except at frequencies close to 6 GHz, where the highest ECC values are 0.13 and 0.16 in free space and with user hand, respectively. However, Gaussian APS with different ASs shows a significant impact of the ECC. With narrow AS of 10 • , ECC at some incident directions can be as high as 0.84 (in free space) and 0.92 (with user hand), and the mean ECC values under this AS are 0.25 (in free space) and 0.37 (with user hand). ECC values keep decreasing as AS gets wider, with the maximum ECC at AS = 70 • observed to be 0.23 and 0.34 in free space and with user hand, respectively, whereas the mean ECC values are close to uniform APS. Statistical distribution of the ECC showed good agreement with exponential distribution, with a better agreement between measured ECC and exponential distribution observed in free space with wider AS.
A novel dual‐band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications is designed and investigated. The proposed antenna operates at 3.5 and 5.25 GHz bands. High port isolation is achieved using hybrid feeding mechanism that excites two orthogonal modes at each frequency bands. The measured impedance bandwidth of the proposed antenna covers the entire WiMAX (3.4–3.7) GHz and WLAN (5.15–5.35) GHz bands. The scalable behavior along with the frequency ratio of the antenna has also been investigated in this work. The measured isolation between antenna ports is −52 dB at the lower band and −46 dB at the upper band, respectively. Envelope correlation coefficient, diversity gain and mean effective gain have also been investigated. Moreover, measured results are in good agreement with the simulated ones.
This study presents work carried out on a multiband‐dielectric resonator antenna (M‐DRA) for long‐term evolution (LTE) application. A new stack M‐DRA is introduced by using two dielectric resonators of different permittivities, stacked on top of each other. The M‐DRA is excited using a coaxial probe. The introduction of a finite planar conducting wall reduces the overall size of the proposed M‐DRA. It operates at LTE band‐VI (828–880 MHz), GSM 1800/1900 and UMTS 2100 for S11<−10 dB. The measurements performed with a fabricated antenna showed good agreement with the simulated results.
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