No abstract

In this paper, the design of an Ultra Wide Band (UWB) hemispherical antenna with Log-Periodic Elements (LPEs) capable of operating at multiple resonating frequencies lying in L, S, C, X, and Ku frequency bands is presented. The design consists of a complex structure of silver hemisphere with LPE mounted on an FR-4 substrate fed by a 50 Ω microstrip line. The dependency of the inclination of log-periodic elements mounted on the hemisphere is analyzed with parametric study. The proposed miniaturized antenna uses LPEs to obtain an impedance bandwidth of above 100% and a multidirectional radiation pattern. The measured results show that a wide operating band of 12.63 GHz (1.68 GHz-14.31 GHz) (8.52 : 1) has been achieved with a multi-directional radiation pattern with a peak realized gain of 8.12 dBi.

A compact Printed Log-Periodic Curvilinear Monopole Array (PLPCMA) antenna having a Defected Ground Plane (DGP) is proposed and examined. The proposed array of curvilinear monopoles is designed on a FR-4 substrate having a dielectric constant of 4.4. The designed antenna is multi-band operated having its resonance in the regions of S band (2GHz to 4GHz), X band (8GHz to 12GHz) and C band (4GHz to 8GHz). The design reveals Voltage Standing Wave Ratio (VSWR) lesser than 1.5 has been achieved at resonating frequencies 2.49GHz, 3.28GHz, 6.84GHz and 8.36GHz with fractional bandwidth of 4.02, 3.66, 50.58 and 41.39 percentages respectively. The presented antenna exhibits unidirectional end-fire radiation pattern with peak realized gain of 7. 1145dBi.The measured results depicts that PLPCMA antenna has good -10dB impedance bandwidth of 158% from 1.58GHz to 15GHz (9.49:1) and suits for Wi-Fi/WIMAX UWB applications.