Abstract: A high altitude communication device is provided using a first array element comprising a plurality of patches and a second array element comprising a plurality of patches. The first array element and the second array element are for receiving communication signals. A patch in the first array element is shared by the second array element. At least one grouping network selects the first array element for a first time interval and selects the second array element for a time interval after the first time interval to convert and form digital combined signals from the communication signals. A method of digitally controlling received signals within a high altitude communication device is also provided.

Abstract: A muffler for use with machines such as pneumatic drills consists of an elastomeric housing divided into an admission chamber and a series of muffler chambers. Within the housing are an inlet conduit communicating with the admission chamber and each muffler chamber, an exhaust conduit communicating with each muffler chamber as well as with a tail pipe outside the housing, and a Helmholtz resonator communicating with the admission chamber.