[Q]radiation field of monopole antenna and dipole antenna
[Q]radiation field of monopole antenna and dipole antenna
(OP)
hi, I am a little bit confused about the filed generated by a monopole and a diapole.
I don't know whether my following statements are true or false:
in 3D space, a monopole can be expressed by a point source, the intensity of the source is changed as harmonic function(sin), the field generated by this source can be expressed as a scalar field, written in equation: scalar Helmholtz equation:
(\nabla+k^2)\fi=\delta(r)
an intuitive plot of a monopole source can be found here:
http://www.kettering.edu/~drussell/Demos/rad2/monopole.gif
can we say that the radiation field of a monopole is a TE wave? or a TM wave? or a TEM? how to tell the direction of the E or H component in monopole radiation?
then, what'are the directions of E and H in an Z direction Electric Dipole? (which means charges oscillating between two closed points), is that TE or TH wave?
an intuitive plot of a dipole source(x direction) can be found here:
http://www.kettering.edu/~drussell/Demos/rad2/dipole.gif
thanks a lot!
I don't know whether my following statements are true or false:
in 3D space, a monopole can be expressed by a point source, the intensity of the source is changed as harmonic function(sin), the field generated by this source can be expressed as a scalar field, written in equation: scalar Helmholtz equation:
(\nabla+k^2)\fi=\delta(r)
an intuitive plot of a monopole source can be found here:
http://www.kettering.edu/~drussell/Demos/rad2/monopole.gif
can we say that the radiation field of a monopole is a TE wave? or a TM wave? or a TEM? how to tell the direction of the E or H component in monopole radiation?
then, what'are the directions of E and H in an Z direction Electric Dipole? (which means charges oscillating between two closed points), is that TE or TH wave?
an intuitive plot of a dipole source(x direction) can be found here:
http://www.kettering.edu/~drussell/Demos/rad2/dipole.gif
thanks a lot!





RE: [Q]radiation field of monopole antenna and dipole antenna
1. John David Jackson "Classical Electrodynamics," 2nd Ed., John Wiley & Sons, 1975
1a. There is a section 9.2 Electric Dipole Fields and Radiation and Figure 9.1 Short, Center-Fed, Linear Antenna
For radiation zone:
Bv=(k**2.(nv x pv).exp(ikr))/r
Ev=Bvxnv
where
Bv is magnetic induction vector (v stands for a vector (typical))
Ev is electric field vector perpendicular to nv (unit vector in direction of xv)
k is constant (wave number =w/c)
i is complex number imaginary unit
r is radial distance
1b. The Monopole is addressed in section 9.1 Fields and Radiation of a Localized Oscillating Source
For the scalar potential FI,
FImonopole(xv,t)=q(t'=t-r/c)/r
where q(t) is the total charge of the source.
The electric monopole part of the potential (fields) of a localized source is of necessity static. The fields with harmonic time dependence, exp(-iwt), w><0 have no monopole terms.