Wire Screen
Reflective Insulation
SFiber-optic Cable
Flat Plate Antenna Fiber-optic Cable
Cable
Ground Rod
Figure 3-14. Diagram of an installation of a MSE measurement utilizing a flat-plate
antenna.
themselves from the external environment. A drawing of this configuration is shown in
Figure 3-14. This configuration is very similar to that described in (Crawford 1998).
3.3.1.3 Electric field measurement implementation
As described in Section 3.3.1.1, essentially the only feature differentiating
an electric field measurement and an electric field time-derivative measurement
implemented with identical flat-plate antennas is the choice of the load impedance
of the antenna. This choice is not trivial, however, and an improper choice of circuit
parameters will almost certainly lead to a poor-quality measurement. Also, as stated
previously, the load impedance will be considered to be an integrating capacitor, Cint, in
parallel with a load resistance, R. The integrating capacitance affects both the gain and
the decay time-constant of the antenna while the load resistance only affects the time
constant. The antenna capacitance must, in general, also be taken into account but it
can be ignored if the integrating capacitance is much greater.
Cint >> Cant
(3-55)