Present radiators required. One such efficient radiators is

Present scenario of communication, all wired ones replacing with wireless. So, to achieve efficient communication in wireless technology, efficient radiators required. One such efficient radiators is Dielectric resonator antenna. The extremely wide spectrum of 3.1 to 10.6 GHz with 15 bands of bandwidth greater than 500 MHz and power limit less than – 41.3 dBm/MHz announced by FCC for Ultra wide band. The release of this Spectrum has rapidly increased the research in UWB technology for communications, radar imaging, and localization applications. Radio systems based on UWB technology offer opportunities for transmission of high data rate signals, coding for security and low probability of intercept, especially in multi user network applications . UWB communication systems have the promise of very high bandwidth, reduced fading from multipath in mobile communication and low power requirements. In general, UWB radio systems transmit and receive temporally short pulses without carriers or modulated short pulses with carriers. Carrier free UWB radio systems usually employ very short pulses in the order of sub nanosecond (ns) as opposed traditional communication schemes which send sinusoidal waves. DRA is one of the best antennas for UWB applications due to its attractive features like high radiation efficiency, low dissipation loss, small size, light weight, and low profile. Moreover, DRAs which possess a high degree of design flexibility, have emerged as an ideal candidate for wide band, high efficiency, and cost-effective applications. Second antenna is designed which resonates at 5.5 GHz which is suitable for 802.11a WLAN applications. The return loss of proposed antenna is -22.7dB at 5.5GHz. Third antenna is designed to resonate at two different frequencies one at 2.42 GHz and other at 9.13 GHz with dielectric constant of 10. The feeding mechanism used is CPW feeding. This CPW feeding structure has many useful characteristics like low radiation leakage, less dispersion, little dependency of the characteristics impedance on substrate height and unipolar configuration. Same antenna is fabricated with dielectric constant of 2.1 and measured the return loss, which is resonating at 3.5 GHz which can be used in WIMAX. The simulated and measured results shows that as the dielectric constant of DRA is increasing the resonant frequency shifts towards the lower frequency and as the dielectric constant is decreasing the resonant frequency is shifting towards higher frequency and the frequency of operation is also changing.

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