Scattering from periodic arrays of crossed dipoles

An analysis is presented for calculating the scattering from periodic arrays of symmetrical crossed dipoles. It is shown that in general the reflection coefficient versus frequency of symmetrical crossed-dipole arrays exhibits two distinct resonances, which occur when the dipole elements are on the order of a half-wavelength long. The analysis reveals also the presence of an antiresonance, which occurs at a frequency between the two resonances. At the antiresonant frequency the array reflection coefficient is zero. Thus, within a relatively narrow frequency band, the array reflection characteristics traverse the extremes of complete reflection followed by no reflection, and finally by complete reflection again. The anomalous reflection versus frequency behavior in such arrays is shown to be directly attributable to two distinct resonances excited in the crossed elements. For an isolated crossed dipole, it is shown that the total induced current can be approximately represented by two uncoupled current components. The current components induced on the same elements in an array, however, are coupled to one another through interaction with neighboring elements. The coupling results in complete cancellation of the total bistatic array scattering, at a frequency which lies between the two component current resonant frequencies.