Design of quad element MIMO array with EBG structure for mutual coupling reduction

Multiple Input Multiple Output (MIMO) array antennas that may transmit radio waves in various patterns and polarizations have been increasingly important in current telecommunication systems. However, the mutual coupling effect is the major drawback of the MIMO system. Electromagnetic Band Gap (EBG) is a good solution for planar arrays to reduce the effects of mutual coupling. A simple EBG structure has been proposed in this paper to reduce the mutual coupling effect for a quad element (2×2) MIMO array. First, a single inset-fed microstrip patch antenna has been designed that resonates at 4.2 GHz with minimum return loss as low as -40 dB. A rectangular shape EBG structure with a dimension of 6 × 13 mm has been implemented between the radiating patches. Each EBG unit cell consists of 3 rectangular shape slots with a dimension of 2×3 mm. The simulation result shows that the antenna can radiate around 95% of its power to the receiver and gives a good directive pattern as well. The quad-element MIMO array with the EBG structure has a minimum return loss of less than -50 dB and maximum isolation of more than 20 dB. Therefore, a quad-element MIMO array with the proposed EBG structure can provide better performance in 5G applications

Controlling Factors on Petrophysical and Acoustic Properties of Bioturbated Carbonates: (Upper Jurassic, Central Saudi Arabia)

Many of the world’s productive Jurassic reservoirs are intensively bioturbated, including the sediments of the Upper Jurassic Hanifa Formation. Hydrocarbon exploration and production from such reservoirs require a reliable prediction of petrophysical properties (i.e., porosity, permeability, acoustic velocity) by linking and assessment of ichnofabrics and trace fossils and determining their impact on reservoir quality. In this study, we utilized outcrop carbonate samples from the Hanifa Formation to understand the main controlling factors on reservoir quality (porosity and permeability) and acoustic velocity of bioturbated carbonates, by using thin-section petrography, SEM, XRD, CT scan, porosity, permeability, and acoustic velocity measurement. The studied samples are dominated by Thalassinoides burrows that have burrow intensity ranging from ~4% to 27%, with porosity and permeability values ranging from ~1% to 20%, and from 0.002 mD up to 1.9 mD, respectively. Samples with coarse grain-filled burrows have higher porosity (average µ = 14.44% ± 3.25%) and permeability (µ = 0.56 mD ± 0.55) than samples with fine grain-filled burrows (µ = 6.56% ± 3.96%, and 0.07 mD ± 0.16 mD). The acoustic velocity is controlled by an interplay of porosity, bioturbation, and mineralogy. Samples with relatively high porosity and permeability values (>10% and >0.1 mD) have lower velocities (<5 km/s) compared to tight samples with low porosities and permeabilities (<10% and <0.1 mD). The mineralogy of the analyzed samples is dominated by calcite (~94% of total samples) with some quartz content (~6% of total samples). Samples characterized with higher quartz (>10% quartz content) show lower velocities compared to the samples with lower quartz content. Bioturbation intensity, alone, has no control on velocity, but when combined with burrow fill, it can be easier to discriminate between high and low velocity samples. Fine grain-filled burrows have generally lower porosity and higher velocities (µ = 5.46 km/s) compared to coarse grain-filled burrows (µ = 4.52 km/s). Understanding the main controlling factor on petrophysical properties and acoustic velocity of bioturbated strata can enhance our competency in reservoir quality prediction and modeling for these bioturbated units