Velocity propagation, electrical signal

The velocities of the propagation of electrical signals that have values from 0.0005 to 40m/s are sufficiently high to facilitate rapid long-distance communication and account for the rapid response phenomena observed in plants. Both the speed of propagation and the duration of action potential depend on the type of external stimulus. 

Of equal importance for this particular application, however, is the dielectric permittivity, e, which determines the velocity of propagation (Vp) of electric signals. As Vp l/Vi, the dielectric permittivity should be minimized to maximize the speed of signal transmission. Figure 11.14 shows different ceramic substrate materials in a plot. Clearly, a compromise is always required, and target materials suitable for electronic substrate and chip carrier apphcation should be... 

For coaxial cables, the following electrical properties related to the dielectric constant of the core material and the dimensions determine the quaUty of the signal impedance, capacitance, attenuation, crosstalk, and time delay and velocity of propagation. 

Bartlett and Corle [46] proposed modification of Maxwell s equations in the vacuum by assigning a small nonzero electric condictivity to the formalism. As pointed out by Harmuth [47], there was never a satisfactory concept of propagation velocity of signals within the framework of Maxwell s theory. Thus, the equations of the latter fail for waves with nonnegligible relative frequency bandwidth when propagating in a dissipative medium. To resolve this problem, a nonzero electric conductivity ct and a corresponding current density... 

Fromm and Bauer [36] found that action potentials in maize sieve tubes change phloem translocation. Using macro- and microautoradiography in mature leaves of maize, Fromm and Bauer [36] studied the inhibition of phloem translocation caused by electric and cold shock. They stimulated the leaf tip with ice water and found that the velocity of signal transmission was 3-5cm/s. Upon stimulation, the microelectrode recorded a basipetally propagating action potential with a depolarizing amplitude of 80 mV in the sieve tubes (Fig. 2). During electrical stimulation, the action potential was measured in the sieve-tube system with a speed of 5cm/s. 

Pis are used in mieroeleetronies industry as interdielectric layers, passivation layers and a-particle barriers. The electrical performance of Pis in these applications is dictated by its dielectric constant and can be further improved by reducing the dielectric constant. The propagation velocity of signal in microelectronic devices is inversely proportional to the square of the dielectric constant of the propagating medium. Therefore, signal propagation in microelectronics devices is faster, when the dielectric constant is low. Fnrther, lower dielectric constant materials reduce crosstalk between adjacent circuit lines and transmission delay time. 

---