Wide-field coded-mask x-ray cameras for SAX

The two wide field cameras that will be flown on SAX and which we describe here will be used to image the x-ray sky in the energy range from 1.8 to 30 keV. The field of view is 20 degrees at FWHM, the angular resolution is five arcminutes (FWHM), and the energy resolution is 20% at 6 keV, while the source location accuracy is better than one arcminute. The design is based on the coded mask principle where mask and detector both have equal sizes of about 25.6 multiplied by 25.6 cm2 square. The detector is a multi wire proportional counter filled with 2.2 bar xenon gas with 5% carbon dioxide, the position resolution is better than 0.5 mm. The mask consists of a 0.1 mm thick stainless steel plate with a hole pattern. The pattern is based on a so called triadic residue set with elements of 1 mm2 of which 33% are transparent for x rays. The sensitivity of the WFCs is a few mCrab in 105 seconds. The principle of image reconstruction is presented and some calibration results. Details on the SAX mission and its instruments can be found elsewhere in these proceedings, as well as a detailed description of the detector.