A Circularly Polarized Broadside Radiating “Herringbone” Array Design With the Leaky-Wave Approach

A series-fed “herringbone” microstrip traveling wave circularly polarized antenna array is designed to achieve broadside radiation. It is shown that such an antenna can be modeled as a periodic leaky-wave (LW) structure, providing insight into radiation characteristics of interest, such as the directivity and beam angle of the structure, particularly at broadside. Full-wave simulations as well as a prototype of the design verified the approach. The extracted leaky-wave number properly predicts the behavior seen in radiation measurements, and no degradation in antenna gain is seen at or near broadside.