Coaxial line cell termination

In the overlapping range 1500-15000MHz the results were obtained using a coaxial line cell terminated by a movable short circuiting plunger( 7). 

Figure 3. Simplified schematic drawings of dielectric sample cells for reflection measurements, (a) Lumped capacitance cell, (b) End capacitance cell, (c) Open coaxial line cell, (d) Coaxial line cell with 50 ohm termination. Bottom sections in all cases are 50 ohm 7 mm precision coaxial lines.

The sample termination section or cell can be so simple as the end of a coaxial line inner conductor in contact with liquid filling a volume bound by the outer conductor or placed between the end and a grounded plane terminating the outer conductor. These and other arrangements have, again from transmission line theory, an admittance y. (ito) related to... 

The admittance of the sample cell terminated by the coaxial line is then given by... 

Two basically different kinds of cell arrangement can be distinguished those in which the dielectric filled section terminates the coaxial pulse generating and sampling line, and those in which this section is itself terminated by a further admittance. The former are usually simpler and more useful, but the latter can have advantages for some purposes. If the sample section is symmetrical with respect to interchange of its input and output connections, and is terminated by an arbitrary admittance yj, its input admittance is given from network theory by... 

---