Resonant circular patch microstrip antenna with air gap
The resonant frequency and bandwidth characteristics of superstrate loaded air gap tuned circular patch microstrip antenna are investigated for different structural parameters. The problem is formulated in spectral domain and Galerkin's method is used for the solution. It is shown that adjustable air gap between the ground plane and substrate compensates superstrate loading effect on the resonant frequency, increases bandwidth and provides tunable operational characteristics.
Hankel transform domain analysis of dual-frequency stacked circular-disk and annular-ring microstrip antennas
A theoretical and numerical analysis of the dual-frequency stacked circular-disk and annular-ring microstrip antennas is discussed. The problem is formulated in the Hankel transform domain. First, the Green's function is derived, relating the transformed electric surface currents on the patches and the transformed tangential electric field components on the substrates. Galerkin's method is used with Parseval's relation for Hankel transformation to solve for the resonant frequencies and the unknown currents. The far-zone radiation patterns are expressed in terms of the transforms of the currents. Numerical results obtained for the resonant frequencies and radiation patterns are found to be in excellent agreement with the experimental data available in the literature. >
Parboiled rice effluent: A wastewater niche for microalgae and cyanobacteria with growth coupled to comprehensive remediation and phosphorus biofertilization
Abstract The potential of microalgae and cyanobacteria for bioremediation of wastewater by nutrient uptake combined with simultaneous biomass production is a well recognized perception of today's world. The present study illustrates the treatment of a highly polluted wastewater generated during parboiling of paddy in rice mill industries, widely operational in developing countries where rice is the staple food crop, with the help of microalgal and cyanobacterial isolates capable of growing at high rates in parboiled rice mill effluent (RME). This endeavor leads to comprehensive bioremediation of the said effluent and subsequent use of the harvested biomass as slow release phosphorus biofertilizers and the treated effluent for crop irrigation. The RME-acclimatized algal consortium demonstrated highest growth in terms of fresh weight and greatest remediation efficiency at the end of 36 days' treatment of RME, with 93.9% phosphorus and 100% ammonia-nitrogen removal, 98.7%, 91.6% and 93.5% reduction in biological oxygen demand, chemical oxygen demand and total dissolved solid, respectively, and an increment of 186 ± 0.3 mg L − 1 dissolved oxygen, bringing down the pollutants level well below the discharge limits suggested by Central Pollution Control Board, India. Additionally, microalgae in the consortium aggregated in clumps spontaneously in presence of the filaments of Phormidium sp. facilitating easy harvest. The RME-acclimatized algal consortium demonstrated highest accumulation of polyphosphate (poly-P) (0.76 ± 0.01% of dry weight) as well as highest release of phosphorus in non-sterile soil emphasizing the essential role of soil phosphorus solubilizing organisms to leach soluble phosphorus from the insoluble poly-P present in the biomass. The rice seedlings watered with treated RME also showed improved growth effect on shoot height and leaf width. The study results establish the suitability of RME as an excellent growth media for microalgae and cyanobacteria.