This paper proposes a hybrid decoupling method based on a novel electromagnetic bandgap (EBG) structure and hair-pin shaped defected ground structure (DGS) to obtain high isolation between 2element multiple input multiple output (MIMO) antenna at 5G millimeter wave band over 27.5−28.35 GHz. The proposed EBG designed on stacked dielectric substrates, achieves a wide frequency band-gap between 26.2−32.03 GHz (20 %). A 2  3 array of the EBG is arranged between two electromagnetically coupled radiating patches in order to suppress the surface wave coupling. Substrate integrated waveguide (SIW) feeding network and cavity are strategically incorporated in the antenna design for improving the radiation performance and minimizing the losses from the feed. EBG shows an average isolation improvement of 13.9 dB within 5G band as compared to unloaded MIMO antenna. The additional reduction in coupling is achieved by placing hair-pin DGS (HP-DGS) on the ground plane, resulting into maximum isolation improvement of 47.7 dB at 27.94 GHz. The prototype of the MIMO was fabricated and experimentally verified. Measured peak isolation between the antennas is obtained as 71.9 dB, having a gain of 9 dBi and front to back ratio (FTBR) of 19.8 dB. A good diversity diversity performance is also noticed for the designed MIMO with envelope correlation coefficient (ECC) of 0.00015, diversity gain (DG) of 9.99 and channel capacity loss (CCL) of 0.025 bits/Hz/sec. Later, SIW corporate feed network is designed for 4-element linear array loaded with EBG and HP-DGS to achieve higher gain and narrow beamwidth. The array was fabricated and the measured results are found in good accordance with the simulation results. The peak gain, beamwidth, and FTBR of the array are 13.3 dBi, 16.2, and 19.97 dB respectively.INDEX TERMS Antenna array, defected ground structure (DGS), electromagnetic bandgap (EBG), mutual coupling reduction, multiple input multiple output (MIMO)

Purpose Rubber leaves are the abundant agro-waste and pineapple, the most economically important fruit crop in Tripura. So, in our present study, different amounts of rubber leaf vermicompost have been applied to the soils of pineapple plantation to determine their effects on earthworms-the soil ecosystem engineers, coupled with the vegetative growth and yield of pineapples. Methods During 30 months of field trial (2010-2012) in ICAR regional station, Lembucherra, West Tripura, the control plot (T 0 ) received no fertilizer, while experimental plots were fertilized with four different amounts of vermicompost viz. T 1 (5 tons ha -1 year -1 ), T 2 (10 tons ha -1 year -1 ), T 3 (20 tons ha -1 year -1 ) and T 4 (30 tons ha -1 year -1 ). Results A significant (p \ 0.05) but gradual increase in density (up to T 3 treatment) and biomass (up to T 4 treatment) of earthworms were recorded with the increasing amounts of vermicompost. During the second year, average length and width of leaves, number of leaves per plant, plant girth, fruit weight, fruit yield and fruiting percentage were highest in the T 3 plot compared to other treated plots and control. ConclusionThe present study reveals that crop yield is very much related to the particular concentration of vermicompost, beyond the level of which production declines and increase in vegetative growth, fruit weight and fruiting percentage of pineapple are strongly linked with the soil pH, av. P, av. K, clay content and the earthworm density of soils.

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