Abstract: A housing for a microwave circuit is formed from a base made of metal matrix composite material and walls made of sheet metal. The base and the walls are joined together by diffusion soldering. Some holes to receive feedthroughs are formed at the junction of the base and a wall.

Abstract: A personal dust spectrometer for aerodynamically classifying and collecting sub-fractions of inspirable dust, has an entry which has an entry efficiency approximating that of the human head during inhalation, and a cascade impactor comprising a stack of stages each having a flat element and a peripheral wall and gas exit holes. A connector enables a gas sampling pump to be attached to draw air through the entry and through the cascade impactor. A filter is desirably used to collect the smallest dust particles. All the dust entering the device is collected and is measurable.

Abstract: A personal dust sampler, for example to be carried on the lapel of a wearer, has a body part with a gas entry protruding therefrom. The entry has an aspiration efficiency of approximately unity for the gas flow rate of a pump (not shown) which is attachable to an exit from the body. Mounted inside the body is a filter which is removable for examination after a sampling period.

Abstract: A sampler for "total dust", exhibiting inspirability characteristics similar to the human head, has a filter unit containing a filter. The capsule has a lipped entry which protrudes through an aperture in a sampling head. The sampling head is connectd to suction elements for drawing an atmosphere through the filter unit and is capable of being continuously rotated.

Abstract: A portable aerosol dust spectrometer has an inlet section with a sampler entry having an entry efficiency for airborne dust approximately to that of the human head during inhalation, a clean-up stage to remove particles above 15 .mu.m and a main collection stage which is a cascade impactor. The cascade impactor classifies particles of dust and collects fractions onto a number of collection surfaces. A pump draws air or gas through the apparatus. The apparatus samples air in a similar way to the human body and yields fractions of dust for further study.