Printed Newton's egg curved monopole antenna for ultrawideband applications

The edge curve of a planar antenna significantly influences its radiation properties. In this study, a novel egg curve-based design of printed monopole antenna of size 40 x 40 mm(2) is proposed for ultrawideband (UWB) applications. The egg shape of the proposed antennas is obtained by Newton's diverging parabolas curve referred in this study as Newton's egg curve. The design equations of the proposed antenna are developed. The variation in impedance bandwidth (BW) with various parametric variations of design curve is studied. The proposed Newton's egg curved monopole antenna (NECMA) is designed, fabricated and measured to validate the theoretical design. Good agreement between the simulated results and the measured ones is observed. An empirical formula is also proposed to approximately determine the frequency corresponding to the lower edge of -10 dB operating BW. The results show that the proposed NECMA can obtain the measured BW of 116.55% (2.9-11.0 GHz) along with stable gain of about 2.2-2.9 dBi. The proposed antenna exhibits almost omnidirectional radiation patterns with low cross polarisation in all directions and consistent group delay over the entire UWB bandwidth (3.1-10.6 GHz).