Design and performance of a lumped resistively loaded spiral antenna

A novel spiral antenna with miniature configuration is proposed by introducing lumped resistive loading along the spiral arms. A transmission-line model incorporating the loss resistance is introduced to help study the method. Numerical simulation examples have been demonstrated that antenna size could be reduced significantly while maintaining the axial ratio characteristics. A partly loading structure was investigated to raise the gain at lower frequencies. The designed antenna was implemented and measured, which achieved a size reduction of 58%.