Design of ultra wideband trapezoidal shape slot antenna with circular polarization
A CPW-feed printed slot antenna with circular polarization characteristics is presented in this paper. The basic structure of the antenna is a rectangular slot excited by a 50? CPW line terminated on a trapezoidal shaped tuning stub. Perturbations in the form of circular stubs are applied in the slot to realize circular polarization. The measured impedance bandwidth (S11<?10dB) for the initial design is 4.4GHz (from 2.2GHz to 6.6GHz) while the 3-dB axial ratio bandwidth is 1.77GHz (from 4GHz to 5.77GHz) which is 36.23% at the center frequency of 4.88GHz. The basic structure of the antenna was further modified to enhance the impedance bandwidth to reach well beyond 12GHz while increasing the ARBW to 44.3% (from 4.3GHz to 6.75GHz). The proposed antenna in its final version has a measured peak gain of about 5dB throughout the useful band and nearly stable radiation pattern.
slot antenna circular polarization cpw-feed monopole antenna ultra wideband system