 Waveguides are metal conduits used to confine and direct radio signals. They are usually made of brass, but aluminium and copper are also used. Most commonly they are rectangular, but other cross-sections such as circular or elliptical are possible. A waveguide filter is a filter composed of waveguide components. It has much the same range of applications as other filter technologies in electronics and radio engineering but is very different mechanically and in principle of operation.
