An Asymmetric CPW-Fed Rectangular Slot Loop Antenna for Wideband Circular Polarization

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A wideband circularly polarized rectangular slot loop antenna excited asymmetrically by CPW for wireless communication systems is proposed. The proposed design has a simple antenna structure and is easy to fabricate. The shape of the proposed antenna is rectangular, which is different from the conventional square circularly polarized slot loop antenna. With the asymmetric CPW feeding structure and the truncated ground plane, the current distribution on the ground plane will be interfered, thus the circular polarization can be obtained in a rectangular design. The length of the protruded signal line of the asymmetric CPW feeding structure can be adjusted for good impedance match. A left-handed circularly polarized radiation in the broadside direction of the antenna with wideband characteristic has been achieved by adjusting the parameters properly. The measured 3 dB axial ratio bandwidth is within the measured -10 dB impedance bandwidth and has a bandwidth of 28.6%, which is wider than other circularly polarized slot loop antenna in the literature. The details of the antenna design are discussed. Experimental and simulated results are also presented and discussed in the thesis.