Frequency-scanned gratings consisting of photo-etched arrays

Frequency-scanned gratings consisting of periodic arrays of thin conducting elements are investigated. The principle used is to let the first higher-order diffracted wave propagate and serve as the frequency-scanned beam. The grating structures are designed for optimum blazing to the desired diffracted wave (i.e., for optimal power conversion from the incident wave to the diffracted wave) by the use of an iterative optimization process. Both reflection and transmission gratings are considered; the elements investigated are single dipoles and crossed dipoles. The theoretical analysis is based on Floquet's theorem and the method of moments. Several numerical examples are presented showing that this type of grating structure has a high blazing efficiency and is suitable for frequency scanning. The theoretical results are verified by comparison with experimental results