Printed Circularly Polarised Asymmetric Ultra-Wideband Antenna
Printed, circularly polarised, microstrip line fed antenna having asymmetric slotted structure is presented. Two antennas, antenna 1 (A1) and antenna 2 (A2), having the same design but radiating with opposite senses of circular polarisation are fabricated. The geometrical structure consists of uneven combination of elements fixed through parametric variations. The measurements yielded significant impedance bandwidth (IBW) and axial ratio bandwidth (ARBW) for axial ratio (AR) ≤ 3 dB. A1 offered IBW of 9.67 GHz (2.46-12.13 GHz, 132.6%), ARBW of 7 GHz (4-11 GHz, 93.33%) and a peak realised gain of 4.05 dBi. A2 offered IBW of 10.05 GHz (2.55-12.6 GHz, 132.7%), ARBW of 7.3 GHz (3.9-11.2 GHz, 96.7%) and a peak realised gain of 4.1 dBi. This constitutes a wide coverage of over 88% of the ultra-wideband (UWB) spectrum (3.1-10.6 GHz). Omnidirectional radiation patterns and marginal group delays are the other features of these antennas. The proposed design is validated through simulations and experimental investigations.