When I was in my senior year of high school, my science project was to construct an experiment that measured the transient response of a mass on a spring to changes in a driving force and to show that this followed the same mathematics as an electrical tuned circuit
. I learned that there were actually two useful analogies; one where the mechanical mass is analogous to capacitance and the other where it is analogous to inductance.
Utilising the eddy current principle, this combination forms a tuned circuit
with the target material and variations in probe face to target distance are detected in this circuit by the driver.
At the operation of a magnetic field on the transistor VT1 there is the variation of equivalent capacity of a tuned circuit
of the self-excited oscillator, which calls variation of its resonance frequency.
Drawbacks to VoIP include the relative immaturity of the technology, the variable delay often associated with routing within the public network, and quality of service of IP networks compared to what we are used to with the well tuned circuit
Proximity or tuned circuit
and electrostatic cards.
The open element of the kit is connected to the tuned circuit
and plugged into the VNA for direct impedance reading.
However, the antenna can now be modeled as a parallel G-L-C tuned circuit
, where the conductance G represents the total losses.
This equation clearly shows that the circuit designer should attempt to keep the carrier frequency as low as possible and the loaded Q of the tuned circuit
as high as possible to achieve the best phase noise.
Figure 7 is the new Smith chart plot of the tuned circuit
. The maximum SWR was changed from 1.70 to 1.04 by adding the matched network.
This is based on the concept that a tuned circuit
, once excited, will oscillate continuously if there is no resistive element present to dissipate the energy.
The power devices themselves have impedances with an imaginary (reactive) part that is on the same order of magnitude as their real (resistive) part, making a tuned circuit
a better choice than a wideband (decade or more) design when only operating over a narrow band.
Alternate approaches using fragile, lower parasitic, single-layer capacitors (SLC) (typically 0.004[inches] to 0.006[inches] thick to achieve useful capacitance values) involve difficult trade-offs between meeting the temperature characteristics necessary for sensitive tuned circuit
and impedance-matching applications, and maintaining the form factor and mechanical robustness necessary for large-scale, surface-mount production.