NOPR Community:

Compact rectangular microstrip antenna with group of slots on ground plane

Fri, 01 Oct 2004 00:00:00 GMT

Title: Compact rectangular microstrip antenna with group of slots on ground plane Authors: Vani, R M; Farida, S F; Hunagund, P V Abstract: A compact rectangular microstrip antenna is realized by embedding slots on the ground plane with increased impedance bandwidth and gain. In this paper the typical configurations of slots are studied by putting group of narrow vertical slots on ground plane parallel to the patch radiating edge. The experimental results show a good agreement with the simulated results. Page(s): 341-343

Investigations of radiation properties of a circular disk microstrip antenna with a slot

Fri, 01 Oct 2004 00:00:00 GMT

Title: Investigations of radiation properties of a circular disk microstrip antenna with a slot Authors: Tiwari, V K; Bhardwaj, V; Saini, J S; Kumar, P; Sharma, K B; Bhatnagar, D Abstract: The radiation characteristics of a circular disc microstrip antenna (CDMAS) carrying a narrow slot on its surface are investigated experimentally and measured results are compared with computed results. The theoretical analysis of this antenna is carried out by applying cavity model-based modal expansion technique. A reasonably good agreement between computed and measured results is recorded which verifies the theoretical formulation applied in this work. Page(s): 336-340

Dielectric behaviour of shale and calcareous sandstone of Jodhpur region

Fri, 01 Oct 2004 00:00:00 GMT

Title: Dielectric behaviour of shale and calcareous sandstone of Jodhpur region Authors: Sengwa, R J; Soni, A; Ram, B Abstract: Dielectric permittivity ɛ' and loss ɛ" of dry and water saturated shale, sandy sandstone (sandy shale) and calcareous sandstone of Jodhpur region were studied at room temperature in the frequency range from 100Hz to 100kHz and also at 10.1 GHz. It is observed that the ɛ' values of these samples decrease with increase in frequency. The complex plane plots(ɛ" versus ɛ') of these geological materials are Cole-Cole arcs. The low frequency limiting dielectric constant ɛ_o, high frequency limiting dielectric constant ɛ, dielectric relaxation time τ and distribution parameter α of these samples have been determined from these Cole-Cole plots. The ac conductivity of dry and water-saturated samples has also been reported. The large enhancement in the permittivity value of water-saturated samples was found due to electrochemical polarization. Further it is observed that the increase in ɛ' value of water saturated shale and sandy sandstone is proportional to the volume fraction of water absorbed in the samples. The effect of the density, porosity, grain sizes and chemical composition on the frequency dependent dielectric permittivity of these samples has been explored. Page(s): 329-335

Emission and scattering behaviour of dry soils from northeast India

Fri, 01 Oct 2004 00:00:00 GMT

Title: Emission and scattering behaviour of dry soils from northeast India Authors: Calla, O P N; Baruah, A; Das, B; Mishra, K P; Kalita, M; Haque, S S Abstract: With the database of the dielectric constants of four dry soils from Assam and one dry soil from Meghalaya, the computations of emissivity and scattering coefficient have been carried out using emissivity model and perturbation model, respectively. The database of estimated emissivity and scattering coefficient have been generated at different frequencies of X-band from 8 GHz to 10 GHz. The estimations are made at 12 different angles of incidence and for both vertical and horizontal polarization. The values of emissivity and scattering coefficient can be used for designing passive and active remote sensing sensors. Page(s): 321-328