Abstract: A cushion includes a center area that is filled with a gel-type material or liquid and is circumferentially surrounded by an outer area that is filled with a beaded-material. In one embodiment, the outer area includes a gel-type material. A bi-directional valve is connected to the outer area to allow only air in or out of the outer area.

Abstract: The requirements of wider bandwidths for communication systems and the resultant use of the millimetre wave region are discussed. The tolerances of filter components for use in the millimetre wave region have required costly manufacturing. E-plane filters (400), a tuning element (450) for such a filter (400), and methods of making and tuning such a filter (400) are disclosed. In particular, the manufacturing (and tuning) technique allows filters (400) of this type to be used at higher frequencies without the need for using higher precision, high cost manufacturing techniques. The filter (400) has at least two waveguide members (410A, 410B) and at least one septum (430) disposed in a waveguide cavity (420) formed by the assembled waveguide members (410A, 410B). The characteristics of the filter (400) are tested.