TEM Mode

A basic question...y do we need two or more conductors for TEM mode to propagate?and y can TM and TE modes propagate in a single conductor transmission line like a rectangular waveguide? If anybody could throw more light, I'd really appreciate it..thx

Yes.

No.

TM and TE modes also propagate in transmission line composed of two conductors.

thnx for the reply...but the question was WHY do we need two or more conductors for TEM propagation...and only a single conductor for TM/TE propagation.thx..

1. Do not think about one or two conductors, both are transmission lines.
2. TEM line can transmit DC, TE,TM waveguide is not capable to do so.