# Radiation power of an antenna

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1. May 25, 2016

### qnach

I am reading Jackson's book on classical electrodynamics.
It said in page 412 to 415 (3rd edition) that the total power radiated by a
dipole is proportional to k^4 (equation 9.24)
quadrupole is proportional to k^6 (equation 9.49)
But why does the linear antenna at page 412, which is a dipole, radiate at k^2 (equation 9.29)?

2. May 25, 2016

### the_emi_guy

The dipole moment, p, has ω in the denominator (equation 9.27). Thus the c2|p|2 terms in 9.24 replace two of the k's.

Last edited: May 26, 2016
3. May 26, 2016

### qnach

so the (real) power for a dipole should be proportional to k^2 instead of k^4 ?

4. May 26, 2016

Yes