In this article, miniaturization of dual‐band slot antenna design for GPS, WLAN and amateur radio applications is presented. The proposed dual‐band miniaturized antenna is achieved using slits, rectangular split ring and metallic strips fed by 50 Ω microstrip feed. The first resonant frequency is achieved by loading reference antenna with eight slits that is antenna 1 and the second resonant frequency is achieved by loading with one center slits and rectangular split ring that is antenna 2. Dual‐band antenna is achieved by loading reference slot antenna with nine slits and rectangular split ring which resonates at frequency of 1.52 and 3.03 GHz respectively. As a result, it is achieved 53.79% reduction in first band resonant frequency with 76.07% improvement in −10 dB bandwidth and 7.90% reduction in second band resonant frequency compared to reference slot antenna. Further, this dual‐band antenna is miniaturized by metallic strips which are placed on the bottom of the substrate. This results in 61.39% reduction in first band resonant frequency with 32.07% improvement in −10 dB bandwidth and 26.13% reduction in second band resonant frequency in comparison with reference slot antenna topology.

In this work, antenna miniaturization using slits and metallic strips fed by microstrip line has been demonstrated. It has been noticed that slot antenna fed by microstrip line provides more miniaturization and in some cases enhanced bandwidth in comparison with the slot antenna fed by other feeding mechanism, keeping the same length and width of the radiating slots, slits and metallic strips. We have achieved 51.67% reduction in resonant frequency and 74.72% improvement in −10 dB bandwidth compared with 37.73% and no bandwidth improvement of either side slits loaded slot antenna topology. Further, it has been shown 63.52% reduction in resonant frequency and 2.23% improvement in −10 dB bandwidth in comparison with 42.33% reduction in resonant frequency of only one side slits loaded slot antenna topology. The current work highlighted not only greater miniaturization and enhanced bandwidth but also almost unperturbed radiation pattern compared to reference antenna topology and low cross-pol level even slot antenna loaded by only one side slits, which was not demonstrated in earlier works.

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In this paper, Multi-Band (MB) OFDM system for Ultra -wideband communication is analysed. Among the many Channel models described in the literature, S-V model is considered for propagation of the MB-OFDM system. The authors have found that complete analysis of the system was not done in the literature. Different code rates were considered as per the implementation of practical systems and the performance was studied with two modulation schemes, QPSK and 4-QAM.Index Terms-Ultra wide band (UWB), WPAN, IEEE 802.15.3a, Channel Model, and OFDM. I. INTRODUCTIONThe UWB system can be defined as a wireless application technology for achieving high transfer rate, low power consumption; low cost, wireless link for short range, low complexity , good order of location and tracking applications and co-existence with the existing narrowband technologies with minimum interference. The UWB works at frequency of 3.1 GHz to 10.6 GHz, an unlicensed spectrum, given by FCC in February 2002. This has led to new standards as IEEE802.15.3a developing high speed short range communication system for personal area network.Another exciting feature of UWB is that this technology allows data rates that can range from a data rate of 55 Mbps at a distance of 10m up to rate of 480 Mbps at a distance of 2m realistic multi-path environments, consuming very less power.The classical UWB systems had the main disadvantage of very wide bandwidth [1] which enhances the problem of building analog and RF circuits with large bandwidth, high speed ADCs for processing the signal and complex circuitry to deal the multi-path energy in multipath path environments. This problem was overcome by pulsed multi-band [2] approach which divides the spectrum into smaller sub bands more than 500 MHz or comparative excess 0.2. Single carrier Hashibul Alam is M-tech student in

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