Abstract: An antenna device for receiving a radio wave transmitted from a communication satellite, converting the received radio wave into an electric signal, amplifying the signal, and outputting the amplified signal to a receiver is capable of quickly resuming a radio wave reception in the event of a failure. The antenna device includes a converter assembly having a straight waveguide and a twisted waveguide for supplying polarized radiowaves in the same direction to two LNBs, which are oriented in the same direction and fixed to a fixing adapter that is slidably mounted on a holder unit. Even when one of the LNBs suffers a failure, the other normal LNB can be used as a spare LNB and simply moved to replace the malfunctioning LNB. Therefore, any malfunctioning LNB can be replaced easily for quick resumption of a radio wave reception. A satellite communication reception system employs such an antenna device.

Abstract: When a satellite among a plurality thereof is designated as well as a polarized signal to be received from this satellite in a receiving satellite switching apparatus, a voltage changeover unit applies a DC feed voltage, which is inputted from a receiver, to whichever low-noise block converter corresponds to the satellite and polarized signal designated. The signal is applied via a coaxial cable. The low-noise block converter to which the DC feed voltage has been applied converts the designated polarized signal from the designated satellite into an intermediate-frequency signal and inputs this signal to the receiver via a mixer by means of a coaxial cable. At this time the DC voltage applied to the coaxial cable is blocked by a DC voltage blocking unit so that it will not enter circuitry which does not require this voltage.