Wide-band planar monopole antennas

The circular disc monopole (CDM) antenna has been reported to yield wide-impedance bandwidth. Experiments have been carried out on a CDM that has twice the diameter of the reported disc with similar results. New configurations are proposed such as elliptical (with different ellipticity ratios), square, rectangular, and hexagonal disc monopole antennas. A simple formula is proposed to predict the frequency corresponding to the lower edge of the bandwidth for each of these configurations. The elliptical disc monopole (EDM) with ellipticity ratio of 1.1 yields the maximum bandwidth from 1.21 GHz to more than 13 GHz for voltage standing wave ratio (VSWR)<2.IEE

New wideband monopole antennas

Several new wideband configurations, such as, elliptical, square, rectangular, and hexagonal disc monopole antennas have been fabricated and results have been compared with the reported circular disc monopole antenna. The elliptical disc with ellipticity ratio of 1.1 yields the largest bandwidth from 1.21 GHz, to more than 13 GRz for VSWR < 2

Ultra-Wideband Antennas

The focus of UWB antenna research activity has matured in recent years and currently mainly concentrates on applications such as biomedicine and security. Early UWB antenna designs were driven by the FCC allocation of spectrum in 2002 and focussed on obtaining wide impedance bandwidths with reasonable group delay characteristics. Many of these were simple planar monopoles antennas with canonical geometries. The emergence of new applications channelled the emphasis towards miniaturisation and integration into devices. This required optimisation of the antenna geometries to ensure that good system performance is achieved from the integrated antenna. Many optimisation techniques are available including the spline technique to generate the outline of the antenna element and ground plane. Simple methods based on genetic algorithms are employed and evolutionary algorithms which are capable of optimising for multiple goals are beneficial when multiple antenna parameters are simultaneously investigated. These techniques have proven advantageous especially when time-domain performance is critical and provide solutions for both single-ended and differential feed arrangements. The main applications using UWB channels in the 3.1 GHz −10.6 GHz spectrum are localization and tracking applications, mainly employing impulse radio UWB imaging, and generally using linear polarization. However circularly-polarized UWB antennas have been developed, both directional and omnidirectional and are being investigated across various systems