An RHCP and LHCP polarization reconfigurable microstrip antenna for ISM band smart city applications

Abstract

In this article, a microstrip antenna having circular polarization switching capability is presented. This antenna consists of a circular-shaped radiating patch with a single co-axial probe feed line. The polarization reconfigurability is achieved by introducing four symmetrical U-shaped slots and silicon PIN diodes on the radiating patch. A prototype of the design is fabricated on an FR-4 substrate with overall dimension of 70 × 70 × 1.6 mm to verify the performances. The measured results of the antenna exhibit an impedance bandwidth (S 11 < −10 dB) of 5% in the frequency range of 2.37–2.49 GHz. The maximum gain of the antenna is found to be 2.99 dBic at 2.43 GHz. The antenna shows stable radiation performances at 2.4 GHz with 4.1% of 3-dB axial ratio bandwidth, and more than 105° of 3-dB axial ratio beamwidth for both right-hand circular polarization and left -hand circular polarization which make it suitable for ISM band Smart city applications.

The Effect of Copper (II) ion on the Production of Citric Acid by Aspergillus niger using Corncobs

“…Also, copper addition is an excellent technique for achieving highest yields [12] reported that generally the growth of Aspergillus species is less affected by the presence of Cu 2+ than Rhizopus species, with the most resistant strain to the copper ions inhibition being Aspergillus niger. [15] also found that copper ions play an important role in minimizing the deleterious effects of iron on citric acid production.…”

“…When the copper ion level is in the right proportion together with operational parameter, the medium will allow high production of citric acid. Copper ion is known to have chelating effect and also been used as an antagonist to iron [14,15]. Furthermore, copper ion addition also provide the advantage of selectively inhibits Penicillia growth as a contaminant [16].…”