Wide-band noise sources using cylindrical gas-discharge tubes in two-conductor lines

The provision of wide-band noise sources for the decimetre wavelength region is important for many radio applications. Anoise signal of suitable power level for most purposes is obtained when the plasma region of a gaseous discharge is matched to a transmission line. Examination of the properties of a discharge plasma shows that a noise source with an output which is constant over several octaves can be obtained by matching a cylindrical discharge tube directly to a two-conductor line. Such matching can be achieved by using conductor pairs of various shapes. The factors which affect the operation of the matching element are considered, and a practical design procedure is outlined. These noise sources are simpler to construct and of better performance than those used previously at decimetre wavelengths.