Phaser-based feeding network for axial ratio bandwidth enhancement in circularly polarized antennas

The paper proposes a differential feeding network with arbitrary frequency-dependent phase difference between the output ports. This network consists of a power divider, a C-section phaser and a TEM transmission line. It is applied to enhance the axial ratio bandwidth of circularly polarized antennas. A design example is provided and the result shows that the axial ratio bandwidth is largely improved by using the proposed differential feeding network.