A circularly polarized broadside scanning patch array

A series-fed microstrip traveling wave circularly polarized antenna array is designed to allow frequency scanning through broadside. The antenna is modeled as a periodic leaky-wave structure. As the structure was developed, the leaky wavenumber kLW was monitored, from which the angle of the main radiation beam and the directivity may be deduced. The design uses a single corner-fed offset patch per cell as radiating elements. The design initially had poor return loss due to the nature of the structure, which is addressed by the introduction of compensation based on transmission line matching. Full-wave simulations as well as a prototype of the design verified the approach. Broadside radiation was achieved. Furthermore, the extracted leaky-wave number properly predicts the behavior seen in radiation measurements.