Low-noise downconverter for use with flat antenna receiving dual polarized electromagnetic waves

A low-noise-block downconverter for use with a flat antenna receiving dual polarized electromagnetic waves, comprising:

• a case body mounted to a rear side surface of said flat antenna and having a partition dividing an interior space of the case body into front and back spaces;
• a pair of input ports provided in said case body so as to correspond respectively to wave guide apertures of said flat antenna for receiving radio frequency signals of said polarized electromagnetic waves of two different types;
• a selective means disposed in said case body for allowing an alternative one of said radio frequency signals of each of said two different types of polarized electromagnetic waves received to pass there through in accordance with a magnitude of a DC voltage supplied from a DC power source;
• means disposed in said case body for converting the frequency of said radio frequency signals of said selected one of the polarized electromagnetic waves received;
• and
• two printed-circuit boards respectively provided with a low-noise amplifier section including said radio frequency signal selective means and with a frequency converter section including a local oscillator circuit, said printed-circuit board of said amplifier section and said printed-circuit board of said converter section being disposed respectively on opposite sides of said partition of said case body so as to respectively lie in said front and back spaces,
• wherein each of said pair of input ports is formed, as viewed in a depth direction of the port, in a rectangular shape having a longitudinal axis, and wherein the input ports are disposed so that the longitudinal axes of the rectangular shapes of the ports are substantially perpendicular to each other.