Varying current or accelaration of charges is required for radiation

Can you say why we need varying current or accelarated charges for radiation? Why don't we get radiation with charges moving with a constant velocity along an infinite conductor line?

Thanks in advance.

I think you should try using constant current which in turn gives constant magnetic field in the wave equations derived from Maxwell's equations. Maxwell's mequations use the dB/dt term which requires a changing B field.

A charge moving at a constant velocity yields a frequency of essentially "DC": not very useful and does not propagate very well! Also impractical as to the size of the required antennas for efficient propagation.

Jim