NOPR Collection:

Broadband and high gain microstrip patch antenna for WLAN

Sat, 01 Oct 2011 00:00:00 GMT

Title: Broadband and high gain microstrip patch antenna for WLAN Authors: Agrawal, Anil Kumar; Pattnaik, Shyam Sundar; Devi, S; Joshi, J G Abstract: A stacked notched rectangular microstrip patch antenna for WLAN applications has been presented in this paper. The desired band is obtained by tuning the dimensions of notches and size of the stacked driven and parasitic patches. The same aspect ratio is maintained for both the patches and their respective notches. The bandwidth and gain of this antenna is 23.6% and 7.5dBi, respectively. Antenna efficiency of 87% is achieved in the designed antenna. The bandwidth, gain, size reduction and efficiency obtained in the designed antenna makes it a potential radiator for various applications. Page(s): 282-286

Design of broadband circular patch microstrip antenna with diamond shape slot

Sat, 01 Oct 2011 00:00:00 GMT

Title: Design of broadband circular patch microstrip antenna with diamond shape slot Authors: Garima; Bhatnagar, D; Saini, J S; Saxena, V K; Joshi, L M Abstract: The radiation performance of a circular patch microstrip antenna having a concentric diamond shape slot has been presented in this paper. The side lengths and angles of the inserted diamond shape slot have been optimized to achieve a single layer multi frequency microstrip antenna applicable for C band space communication systems. For simulation work, IE3D simulation software has been applied and later this antenna has been designed and tested by applying glass epoxy FR-4 substrate. The proposed antenna provides much improved bandwidth (measured impedance bandwidth 0.87 GHz or 13.58%) than a conventional circular patch antenna. The gain of proposed antenna is almost constant in the frequency range where broadband performance is realized, however, it is improved considerably in comparison to a conventional circular patch antenna. The performance of proposed antenna has been compared with that of a conventional circular patch antenna having identical patch radius. The measured co and cross polar patterns of proposed antenna at one of the three resonance frequencies have been presented. Page(s): 275-281

Estimation of emissivity and scattering coefficient of low saline water contaminated by diesel in Cj band (5.3 GHz) and Ku band (13.4 GHz)

Sat, 01 Oct 2011 00:00:00 GMT

Title: Estimation of emissivity and scattering coefficient of low saline water contaminated by diesel in Cj band (5.3 GHz) and Ku band (13.4 GHz) Authors: Calla, O P N; Ahmadian, Nima; Hasan, Sayeh Abstract: In case of low salinity or variable salinity, there is a very shallow radius of investigation. The dielectric constant of low saline water can be significantly modified by the presence of diesel. Techniques based on the propagation of electromagnetic waves may be used to detect contaminant and evaluate decontamination processes. Microwave remote sensing of diesel oil contaminated low saline water requires the study of electrical parameters of low saline water as well as diesel such as dielectric constant, emissivity and scattering coefficient along with their physical parameters like surface roughness, etc. The measurement of dielectric constant is very essential for estimating the emissivity and scattering coefficient. The measurement of dielectric constant of low saline water in combination with diesel has been carried out using waveguide cell with shift in minima method in 5.3 and 13.4 GHz. Tests are conducted with samples of different salinity of water with various amount of diesel oil. The amount of salinity is 5, 10 and 15 kppm and the amount of diesel contamination is from 40 to 280 percent with the interval of 80 percent for Cj band (5.3 GHz) and 40 to 160 percent with the interval of 40 percent for Ku band (13.4 GHz). The estimation of emissivity and scattering coefficient have been done for incident angles varying from 10 to 80 degree with the interval of 5 degree for both horizontal and vertical polarization. The value of Brewster angle has been calculated and the values of emissivity and scattering coefficient for three look angles (45, 50 and 55) degree is presented which are useful for designing space borne active and passive sensors. Furthermore, this database is useful for detecting oil spills in low saline water. Page(s): 267-274

Characteristics of S-W and N-E monsoon rainfall over Salem

Sat, 01 Oct 2011 00:00:00 GMT

Title: Characteristics of S-W and N-E monsoon rainfall over Salem Authors: Jaiswal, R S; Neela, V S; Rasheed, M; Fredrick, S R; Zaveri, L Abstract: The study of rainfall during various seasons in Salem (11^o40’9.97’’N, 78^o8’27.11”E), a town in southern India has been reported in the present paper. The variability has also been discussed in terms of the accumulated rainfall (R), the number of hours of rainfall (RH) and the average rainfall (avg), as well as the percentage occurrence of very low, low, moderate, heavy, very heavy and extreme rainfall in these seasons. A particular effort has been made to determine the effect of El Nino and La Nina on patterns of rainfall. The meteorological parameters, such as cloud liquid water (CLW), precipitation water (PW) and latent heat (LH) have also been determined for various seasons. The study shows that there exists a significant degree of correlation between rainfall and these meteorological parameters. A functional relationship has also been established between the intensity of convective rainfall and CLW, PW and LH. Page(s): 257-266