Reflection properties of periodic surfaces of loaded dipoles

Two-dimensional periodic arrays of dipoles or slots act as reflecting or transmitting surfaces, respectively, which have bandpass filter characteristics. The resonant frequency and the bandwidth may be controlled by varying the length, spacing, and load impedance of the dipoles (slots). A theoretical and experimental investigation of the scattering by a two-dimensional array of loaded dipoles is described. The scattering through the resonance region shows that a unit reflection coefficient is achieved. The effect of grating-lobe radiation is included. The scattering properties as a function of the angle of incidence are given for both loaded and unloaded dipoles. The loaded dipole array described in this paper produces a narrower bandwidth than the array of unloaded dipoles, and the resonant frequency is much less dependent on the angle of incidence. The resonant frequency of the array as well as the bandwidth depends strongly on the resonant frequency of the dipole element as would be expected; however, it is also substantially influenced by the interelement spacing and the angle of incidence.