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A two-element antenna system is introduced with good isolation in this manuscript. The offered °G antenna gets two resonance frequencies at 28/38 GHz. The offered antenna is designed and simulated using industry-standard software CST MWS program. The elementary antenna is conventional microstrip antennas placed at the end of the mobile handset. The obtained reflection coefficient is -27.908 dB from (26.961 - 29.266) GHz with impedance bandwidth of 8.19 % and -20.58 dB from (36.646 - 40.297) GHz with impedance bandwidth of 6.09%. The two ports are coupled with less than −30 dB. The achieved directivity, far-field gain, and efficiency are 7.581 dB i , 7.182 dB i and 91.24 % at 28 GHz and 9.716 dB i , 9.24 dB i and 89.63 % at 38 GHz, respectively. The size of the Rogers 5880 substrate is 55 × 115 mm2 with h = 0.508 mm and E r =2.2 which is a low-cost substrate and small size patches best suited for miniaturized devices.

A novel dual-band two port Multiple-Input-Multiple-Output (MIMO) antenna at 28/38 GHz bands for the approaching 5G wireless applications is configured and manufactured in this paper. The MIMO antenna takes in identically positioned two rectangular slotted patches with inverted I-shaped slots at the lower border of the mobile substrate. The system has an overall size of 55 x 110 x 0.508 mm3. The antenna works in a 1.0683 (27.58–28.649) GHz bandwidth at 28 GHz and 1.4306 (37.213-38.643) GHz 38 GHz. A defected ground construction (DGS) to raise the isolation among the two ports and magnify the antenna radiation is introduced. The isolation is further desirable than -29.4 dB and -27.3 dB for the higher and lower frequencies, respectively among antenna elements. The MIMO antenna is planned and optimized through CST-MW Studio 2017 simulator as well as by measurement. The results from simulation and measurement are in a good agreement in the meaning of reflection coefficients and mutual coupling of the introduced MIMO antenna.

The paper presents an analytcal investigation of the behavior of reinforced high strength concrete slabs. A plasticity-based concrete model is used for the finite element analysis. The details are described of the study in which a suitable post-cracking tensile model of reinforced high-strength concrete was used based on the fracture energy of high strength concrete recorded from stress-displacement curves. The validity of the model is then established by comparison with the test results of reinforced high strength concrete slabs. The behavior of such slabs is examined through a parametric study. The sensitivity of the material model to different properties and edge restraints is also demonstrated.