Showing papers on "Reflector (antenna) published in 2022"

Design and Validation of Flexure-Based Hinges for Space Deployable Antenna Reflector

Abstract: Space exploration arises the demand for launching large-diameter antenna reflectors to satisfy the need of high-bandwidth telecommunication, earth observation and deep space interplanetary missions. Launching of monolithic LDR antennas of sizes 3 m or more is not feasible due to limited launch fairing space of state-of-the-art launch vehicles. Therefore, the development of innovative deployment mechanisms is the present need of the hour. Many researchers have proposed various mechanism options to fold large size antenna reflectors in compact size and deploy in space to full configuration. Deployment process of antenna is process of transition from mechanism to structure which is one of the unreliable stages due to availability of many conventional rotary joints which causes loss of energy due to backlash, friction and misalignment. This paper proposes a solution of replacement of conventional hinges with flexure hinges in state-of-the-art space deployable configuration of large size reflectors, reforming it as compliant configuration which eliminates the factors causing loss of energy. Tape flexures are explored as a suitable candidate for compliant deployable configuration. The proposed configuration consists of two tape flexures mounted in such a way that concave curve of each tape will face to each other. Options with single tape flexure and double tape flexures are explored and compared. Experimental evaluation of a proposed joint configuration is carried out for the development of a deployable antenna reflector.

Experimental Investigation on a Novel Composite Salt Gradient Solar Pond With an East–West Side Reflector

Abstract: A salt gradient solar pond (SGSP) acts as an eco-friendly and cost-efficient device for storing thermal energy storage. It is crucial to enrich the efficiency of the SGSP to boost its thermal energy storage. It can be efficaciously achieved with the application of salt mixtures, reflectors, and by the usage of a glazed layer. This current study investigates the hexagonal composite salinity gradient solar pond (HCSGSP) augmented with a dual inclined reflector and a triple-layer transparent cover. A micro-solar pond having a hexagonal cross section was fabricated and experimented at Coimbatore, India, having a datum and surface area of 1 m and 0.679 m2, respectively. The novel usage of composite salt (sodium chloride 30%, magnesium chloride 10%, and potassium chloride 60%) led to the enhancement of the daily average temperature of pond. The pond’s upper portion was packed with a triple-layer glazed cover which shows an uplift of thermal energy and the pond is provided with inclined reflectors made of plywood fixed with mirrors on the east–west direction. The purpose of the mirrors is to increase the solar radiation intensity during the diurnal period and also it acts as an insulator which minimizes the heat losses during the nocturnal period. Energy balance numerical equations were formulated for all layers in the pond and temperature variation was determined mathematically and experimentally. The maximum thermal efficiencies of the top convective, middle non-convective, and bottom convective layers of reformed solar pond were measured to be 23.44%, 30.68%, and 35.63%, respectively, whereas they were 1.32%, 12.32%, and 23.44%, respectively, in the case of conventional pond. Furthermore, the research provides insight into the impact of shading owing to sidewalls, which has a significant impact on the incident solar radiation and storage of thermal energy in the novel solar pool.

AMC-Loaded Compact CPW-Fed Monopole Antenna for Ka-Band Applications

Abstract: A compact CPW-fed monopole antenna over a periodic arrangement of artificial magnetic conductor (AMC) has been developed for Ka-band application. The 50 Ω coplanar waveguide fed is used to achieve a large bandwidth ranging from 25.76 to 35.86 GHz. The proposed monopole is designed on Roger RT/Duroid 5880 substrate with dielectric permittivity er = 2.2 and tanδ = 0.0001. The full wave simulation tool Ansys HFSS 19.1 is used to simulate and design the proposed antenna. The radiation characteristics of monopole antenna are improved by using AMC reflector surface. The square AMC with four stubs and circular slot is designed for 28 GHz. By using AMC reflector, it is demonstrated that the gain and bandwidth are increased upto 8.76 dBi and 25.76–35.86 GHz (32.7%).