Wide-beam Spiral Antennas with Multi-Folded Arms and Compact Feed Networks for Satellite Application

This paper proposes a new class of multi-fed antennas with folded arms. A compact planar antenna is proposed for wide-beam applications with circular polarization. The fabricated antenna has three multi-folded spiral arms fed by equal signals with 120° out of phase with respect to each other to produce a symmetrical radiation pattern. It is indicated that the number of arms can be changed to say, four or six arms without changing the results. In addition, compact feed networks with Wilkinson power dividers are designed to produce the required phase shifts for the inputs of antennas. Finally some discussions are presented for the quadrifilar spiral antennas and a dualmode antenna with reduced height is achieved.