Low-Cost, Microstrip-Fed Printed Dipole for Prime Focus Reflector Feed

A low cost printed dipole antenna is proposed as a feed for prime focus reflectors. Its geometry is arranged such that the two dipole arms are on opposite sides of a dielectric substrate, fed by a microstrip line. A printed dipole-reflector is placed parasitically in front of the radiating dipole arms to make its radiation backward, toward the microstrip line. This allows mounting the feed centrally on a parabolic reflector from its apex, eliminating the needs for supporting struts. The feed antenna offers an impedance bandwidth of 16.5%, when printed on a substrate of dielectric constant 2.5, and an overall dimension of 60 $,\times,$ 60 $,\times,$ 1.58 ${\rm mm}^{3}$ at 3 GHz. Its impedance bandwidth is enhanced up to 29.1% by modifying the feed line. The pattern symmetry and cross-polarization of the antenna are improved by slightly changing the arms length. Its performance on a small available deep dish, with $f/D=0.25$ and $D=45~{\rm cm}$ , is experimentally calculated at 3 GHz, and overall efficiency of 55% is measured. For further verification, a second feed for operation at 6 GHz is also designed and verified on the same reflector, providing the same level of efficiency.