This paper presents a novel design of a Multiple Input Multiple Output (MIMO) antenna system for next generation sub 6 GHz 5G and beyond mobile terminals. The proposed system is composed of a main board and two side boards. To make the design cost-effective, FR4 is used as a substrate. The design is based on a unit monopole antenna etched at the side substrate. The single element is resonating at $3.5$ GHz attaining a 10 dB bandwidth of 200 MHz and a 6 dB bandwidth of 400 MHz. The single element is then transformed into an MIMO array of 8-elements with an overall dimension of 150 mm × 75 mm × 7 mm, providing pattern diversity characteristics and isolation better than $-12$ dB for any two radiating elements. A number of studies such as effects of human hand on the system that includes single hand mode and dual mode scenarios and the effects of Liquid Crystal Display (LCD) over the principal performance parameters of the system are presented. The envelop correlation coefficient (ECC) is computed for all the scenarios and it is found that ECC is less than $0.1$ for any case and maximum channel capacity is $38.5$ bps/Hz within the band of interest. The main advantage of the proposed design over available designs in the literature is that almost all of the main substrate is empty providing wide space for different sensors, systems, and mobile technology components. A brief literature comparison of the proposed system is also presented. To validate the proposed model, a prototype is fabricated and results are presented. This design can be applied on higher frequencies to future micromachines for on chip communications using same theocratical approach as the space for higher frequencies in mmwave spectrum has been reserved. The simulated results are in an excellent agreement with the measured results. All the main performance parameters of the design are calculated and compared with the measured results wherever possible.

This paper presents a multiple-input multiple-output (MIMO) antenna system for millimeter-wave 5G wireless communication services. The proposed MIMO configuration is composed of four antenna elements, where each antenna possesses an HP-shaped configuration that features simple configuration and excellent performance. The proposed MIMO design can operate at a very wideband of 36.83–40.0 GHz (measured). Furthermore, the proposed MIMO antenna attains a peak gain of 6.5 dB with a maximum element-isolation of −45 dB. Apart from this, the MIMO performance metrics such as envelope correlation coefficient (ECC), diversity gain, and channel capacity (CCL) are analyzed, which demonstrate good characteristics across the operating band. The proposed antenna radiates efficiently with a radiation efficiency of above 80% at the desired frequency band which makes it a potential contender for the upcoming communication applications. The proposed design simulations were performed in the computer simulation technology (CST) software, and measured results reveal good agreement with the simulated one.

In this letter, a novel bianisotropic omega frequency selective surface (FSS) is presented. The distinctive feature of the surface is that it offers simultaneous absorptive and partial reflective operation at seven frequency bands that range from the C-band to the K-Band. The maximum absorption (~ 99%) from one side is obtained at 14.312 GHz, while reflection from the other side remains between 75% and 99%. Moreover, the FSS provides the same behavior for any arbitrarily oriented linear polarized wave as well as circularly polarized waves. Furthermore, the surface is stable against oblique incidences of up to 60° at the lower frequency bands. The proposed FSS has potential applications in Fabry-Perot cavity antennas with reduced radar cross-section (RCS).

A high gain antenna system with improved isolation for 5G applications is proposed and investigated. The radiating structure consists of a combination of multiple strips to make the proposed design resonate within the desired frequency band of 28 GHz being of major interest for 5G applications. The antenna element provides 684 MHz operating bandwidth and a peak gain of 5.85 dB with a radiation efficiency of 70.9%. Using four antenna elements in an antenna array, connected with a T-shaped feeding network, provides a 12.5 dB peak gain and radiation efficiency of 91.5%. The efficiency improvement of almost 20% is achieved by the reduction of the mutual coupling between antenna elements in the array configuration. This also leads to a low side lobe level (SLL) and an improvement in the bandwidth to 1.53 GHz. Furthermore, the four-port multiple-input-multiple-output (MIMO) configuration is obtained using the proposed array configuration which gives an optimum gain, uncorrelated fields, reasonable bandwidth, and isolation of more than 30 dB with a satisfactory MIMO performance metrics. Due to the abovementioned promising features of the proposed antenna design, it can be very useful for important 5G applications.

This paper presents a review of wireless power transfer (WPT) followed by a comparison between ambient energy sources and an overview of different components of rectennas that are used for RF energy harvesting. Being less costly and environment friendly, rectennas are used to provide potentially inexhaustible energy for powering up low power sensors and portable devices that are installed in inaccessible areas where frequent battery replacement is difficult, if not impossible. The current challenges in rectenna design and a detailed comparison of state-of-the-art rectennas are also presented.

The purpose of this study was to characterize the alterations in microstructural organization of arterial tissue using higher-order diffusion magnetic resonance schemes. Three porcine carotid artery models namely; native, collagenase treated and decellularized, were used to estimate the contribution of collagen and smooth muscle cells (SMC) on diffusion signal attenuation using gaussian and non-gaussian schemes. The samples were imaged in a 7 T preclinical scanner. High spatial and angular resolution diffusion weighted images (DWIs) were acquired using two multi-shell (max b-value = 3000 s/mm²) acquisition protocols. The processed DWIs were fitted using monoexponential, stretched-exponential, kurtosis and bi-exponential schemes. Directionally variant and invariant microstructural parametric maps of the three artery models were obtained from the diffusion schemes. The parametric maps were used to assess the sensitivity of each diffusion scheme to collagen and SMC composition in arterial microstructural environment. The inter-model comparison showed significant differences across the considered models. The bi-exponential scheme based slow diffusion compartment (Ds) was highest in the absence of collagen, compared to native and decellularized microenvironments. In intra-model comparison, kurtosis along the radial direction was the highest. Overall, the results of this study demonstrate the efficacy of higher order dMRI schemes in mapping constituent specific alterations in arterial microstructure.