A RF pick-up probe, RF choke, and DC output line that simultaneously receives RF radiation from a waveguide and provides a detected DC voltage provided by a diode RF detector disposed in said waveguide to one or more output video lines. The RF pick-up probe, RF choke, and DC output line are preferably disposed with an antenna transition element for coupling a horn antenna to a matched diode detector which provides the aforementioned DC voltage. The transition preferably includes a ridged waveguide operatively coupled to the horn antenna; a substrate for supporting a diode chip, carrying said matched diode detector, adjacent the waveguide, the substrate also supporting a pair of RF pick-up probes, each RF probe having a portion which is coupled with the diode chip, the substrate also supporting conductors coupled to the diode chip and to the pair of RF pick-up probes; and a waveguide short circuit at least partially enclosing the diode chip and disposed adjacent the substrate.