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Friday, July 11, 2014

Wait A Minute...

From previously,

B=dRv.12πεorE.

since x=i.2πr,    x is tangential to r everywhere

B=idRv.1εoxE

where i was mulitplied to both the denominator and numerator.

Comparing this expression with,

B=iEx

 which leads to the wave equation

 2Et2=2Ex2v2,

with a typical solution of the form,

E(x,t)=Ax.ei(ωt±kx)

We find that, since E can be replaced with D.E where D is a constant, and still satisfy the wave equation,

iEx=iEx

and

D=dRvεo

where i rotates x to the x direction,

Ex=Ex

1EE=1xx

If we consider only the spatial component of E,

E=Cx    over the length of the wire.  Since V=d.E,

C=Vd2

ie.,

E=Vd2.x    where d is the length of the wire.

D.E=VdRvεo.x=Jεo.xd

Since, V=d.D.E

V=Jεo.x

where V is the voltage along the length of the wire.

This is a very interesting result.  It is tempting to suggest that this E field/V voltage profile up the wire antenna is most efficient for radiation at the end of the wire.  Although it is true that this expression for E is derived from B=idEdx, that leads to the wave equation directly.  This seem like impedance matching, but

V=IR=Iεov.d

R=dεov where v is the charge average velocity along the wire that changes with the driving voltage at the end of the wire.

Have a nice day.