Triangular and Rectangular Lattices for Cosecant-Squared-Shaped Beam Reflectarrays

In this letter, we design, analyze, simulate, fabricate, and measure the performance of reflectarrays capable of forming cosecant-squared beam shape. Due to their unique pattern and abrupt change, achieving a cosecant-squared beam is challenging. In our effort, we evaluate the efficacy of a commonly used rectangular lattice and compare it, for the first time, to a triangular lattice. Two linearly polarized reflectarrays, each with 20
λ
₀
diameter in size, are fabricated and tested at 20 GHz. Through statistical methods, we quantify the gain agreement between the desired cosecant-squared mask and the measured beam patterns for both rectangular and triangular lattices. We have found that the rectangular lattice conforms better to the cosecant-squared mask at the design frequency of 20 GHz with a root-mean-square error of 6.27 dB. The triangular lattice conforms less, however, it does allow for an increase in gain bandwidth of 6.2% as compared to 4.5% for the rectangular lattice. Measured and simulated patterns are in a good agreement.