A transceiver capable of processing signals having wavelengths of less than 1 millimeter and/or more than 1 millimeter comprising a mixer/filter circuit coupled to an IF filter where said mixer/filter circuit is positioned within a mixer block to receive incoming signals guided into one or more feed horn openings of the mixer block by an optical arrangement. The IF filter is also disposed within the mixer block, but is positioned substantially orthogonal with respect to the mixer/filter circuit for efficient use of space.