Rain attenuation becomes the prime reason for link failure at frequencies above 10 GHz. C band and Ku band are already exhausted for Indian region satellite communication and time has come to shift to next higher Ka-band. But the attenuation due to rain is very large for this band, especially for tropical country like India. This has led to the development of many rain attenuation prediction models. But to apply rainfall data in these models, fine rainfall data is required which is not available for most locations, and if available, are not for longer durations. In this paper, a novel method is described that can be used for rainfall attenuation prediction for India using coarse rainfall data, that is available from Indian Meteorological Department. Many models are available to predict the 1 min integration rainfall distribution around the world. But for Indian subcontinent, most models show large variations from actual rainfall attenuation. This paper presents estimation of rainfall attenuation for Ka-band for five different regions covering almost whole India using ITU-R model, Crane-Global model and Moupfouma model. These estimations are compared with actual measured results of previous works. The calculated rainfall rates suggest significant variances in the mean rainfall intensity or rate in mm/h. The analysis shows that the ITU-R model overestimates the rainfall intensity rates when empirical model is developed using data from Indian Meteorological Department. It is observed that ITU-R model is best suited for Indian region, but needs modifications to obtain accurate estimation for rain attenuation. Hence a new empirical model named Dafda-Maradia model for rain attenuation for India is proposed. This model is based on ITU-R model and is basically a modified ITU-R model. Here the prediction of rainfall attenuation is done from coarse rain data of 64 years (1951-2014). It is observed that there is a large decrease in the average rainfall intensity as compared to the ITU-R model. Keywords Coarse rainfall data • Dafda-Maradia model • India Meteorological Department (IMD) • Ka-band satellite • Kothyari and Garde equation • Novel method of estimation of rain attenuation

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Radio frequency Identification (RFID) Tags basically consists of antenna as a radiating device and chip embedded as a storing device. The impedance match between two is of prime importance as it decides the overall performance of the tag. This paper discusses various methods to achieve the impedance matching by varying certain antenna parameters while designing it.

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