A Hybrid Cavity-Planar P-band Illuminator for Primary Focus Reflector Antenna

A compact dual-polarized feed operating between 300 and 420 MHz has been designed to illuminate the $32-\mathrm{m}$ parabolic reflector of the Noto radio telescope. The feed combines the compactness of a planar design to the higher illumination performance of a guided solution. Four half-wavelength dipoles distributed in the sides of a square are integrated in a metallic cavity improving the reflector’s illumination. Each pair of parallel dipoles is excited, through a common coaxial port connected to two parallel strip lines, without making use of external $0^{\circ} / 180^{\circ}$ power dividers and/or baluns. Numerical results for the radiation pattern and the matching properties are shown for the single illuminator and after the reflection with the primary dish of the Noto radio telescope.