Array Of Parabolic Reflectors Research Articles

Feasibility Study of Quasi-Optical MIMO Antennas for Radiative Near-Field Links

This article presents a feasibility study of single feed per beam quasi-optical (QO) antennas for enabling incoherent multiple-input multiple-output (MIMO) array front-end architectures at 270 GHz. The objective is to reach ultrafast and radiated energy efficient point-to-point (PtP) wireless links by exploiting the multimode capacity of radiative (Fresnel region) near-field links. In this article, we present a feasibility study of the number of independent links achievable with QO MIMO incoherent arrays. For this purpose, we present theoretical curves of the level of EM co-coupling and interference between the multiple modes versus the link distance. The study focuses at the 252–325 GHz spectral bandwidth defined by the new IEEE 802.15.3d standard. A specific and new MIMO array architecture operating at 270 GHz based on a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> array of parabolic reflectors is proposed for a link distance of 100 m. The proposed PtP MIMO system is capable of generating 16 dual-polarized modes in a 70 GHz bandwidth with signal-to-interference ratio >17 dB and a power co-coupling coefficient of −3 dB without the need for interference cancelation techniques. Combining this architecture with wideband front ends could potentially lead to an aggregated data rate in the order of terabit per second in a PtP wireless line-of-sight link, not previously achieved experimentally to the best of authors’ knowledge.

Experimental analysis of a four slope solar still augmented with a parabolic reflector array with V-shaped mirror arrangement for pre-heating brackish water

For centuries long ground-water, the main source of fresh water for sustaining life, could be found in abundance on planet Earth. The scenario has changed drastically over the past few years as potable water has become a scarce commodity owing to the exponential growth in population. In such testing times man has been forced to look at sources other than ground-water for meeting his daily needs. Even though the yield of potable water obtained is less, desalination of hard water by means of a solar still is an economic method used for obtaining potable water using just the energy from sun. The current research explores the option of increasing the performance of a four slope still with wick by preheating the water before the start of evaporation and condensation cycle. Pre-heating was done using two methods; the first method involved passing brackish water inside Copper tubes and making the tubes pass through an array of parabolic reflectors. The second method involved coupling the parabolic reflector array with a v-shaped mirror arrangement through which Copper tubes were passed. Once preheated, the water was then fed to the four slope solar still for obtaining potable water. The influence of preheating water by the above said two methods on the yield from the still have been compared. The array of parabolic reflectors with mirror arrangement was found to increase the brackish water temperature by 8°when compared to the parabolic reflector array without mirrors. The water at elevated temperature which when fed to the still was found to augment the evaporation process and hence increased the productivity of the still by 10%, which amounts to more than 80 L a year. Hence, performance of a solar still can be improved by incorporating novel and viable solutions.

Rocket Prototype of An X-Ray Optical System for Surveying and Locating Cosmic X-Ray Sources

The characteristics of an X-ray detection system based on an array of parabolic reflectors that provide a line-shaped focus will be described. The most recent rocket instrument has an overall length of about two meters and utilizes a pair of thin-window gas-flow proportional counters for detecting the X-rays. The variation of effective aperture with X-ray energy, the amount of scattering from the mirror surfaces, and the quality of the optical focus will be discussed. Estimates of the sensitivity of a larger set of X-ray optics used as a survey system, and when combined with a special grating to form a spectrograph, will be presented.