Microwave Helix Waveguide Absorption Cell for Passive Frequency Standard

A new closed absorption cell, which has been developed for a passive frequency standard, is described. This cell is made from a cylindrical quartz tube with copper wire wound around it. For the limiting case of the zero pitch helix, Maxwell´s equations are graphically solved, which show that the cell is operating like a monomode waveguide at 23.8 GHz, the frequency of interest, and can be used from 10 to 100 GHz with few modifications.