The spatial filtering effect of capacitance transducer electrodes (flow measurement)

Air-Solids Flow Measurement Using Electrostatic Techniques

“…The mechanism of electrostatic metering system has been studied by many people, for example, Gajewski [19], Massen [20] and Hammer [21] studied filtering effect of the circular electrode, and Yan investigated charge induction based on free space electrostatic field theory [15]. When the Finite Element Method became practically viable with the increased speed and capacity of computers, more in depth study of charge induction became possible.…”

Non-intrusive electrodynamic characteristic measurement for circular shape electrode

“…The frequency bandwidth characteristic or called spatial filtering effect investigation arising from capacitance electrodes was described by Hammer and Green [6]. This investigation also was related to the velocity of flowing discontinuous material to the frequency bandwidth of the sensed signal [8].…”

“…When the pulse duration was short compared with a/v [6] it may be shown that the response is a 'sinc' function with the effect of a and v on the modulus shown graphically in Fig. 2.…”

“…However, some applications maybe requiring rectangular electrodes [7]. The results from the rectangular electrodes can be compared with the measurements obtained using capacitance electrodes [6].…”

“…This paper investigates the relationships between sensor size of circular electrode, sensor sensitivity and the frequency bandwidth and termed the spatial filtering effect [6] of the transduced signals.…”