A Loop-Line Antenna with Wideband Circular Polarization

摘要

Using the moment method, we analyze a loop antenna with parallel wires for circularly polarized (CP) radiation. Special attention is paid to a CP wave bandwidth versus the loop height above the ground plane. It is found that a maximum bandwidth of 8% for a 3-dB axial-ratio criterion is obtained for a loop height of 0.2 wavelengths. This leads to a further analysis of a microstrip-line antenna consisting of the loop elements (loop-line antenna). It is revealed that the CP wave bandwidth is wider than that of a conventional loop-line antenna by a factor of two.