An experimental study of electronic scanning by an antenna loaded with a circular array of ferrite rods

The measured performances of the antenna which consists of a circular array of 12 anisotropic ferrite rods, a truncated biconical horn, and a core wire of a coaxial cable at the center of the biconical horn are presented. The following are made clear. The transmitting pattern having a single big lobe and suppressed sidelobes is obtained by the effects of the appropriate ferrite anisotropy and of the interactions among the ferrite rods. The main lobe cannot be rotated continuously, but at intervals of about30degby gradually changing the axial magnetic fields applied to the respective ferrites; that agrees with what was expected by the two-dimensional theory. Reciprocity does not hold for this antenna: the receiving pattern coincides with the transmitting pattern rotated180deg. Hence, this antenna permits us to receive from a direction and simultaneously to transmit in a different direction. The frequency characteristics of the antenna including the input impedance are also shown and discussed.