The loop antenna is probably one of the oldest antennas in the history of physics and radio engineering. It was Hertz who first noticed that his "sparks" were transmitted through the air using small loop-like antennas spaced just a few feet apart! Since that beginning, magnetic loops have tended to take the back seat in the radio world,
Loop antennas have still perform well today and, even in some cases, outshone their electric-field counterparts? One big reason is performance! Loops can do just as well if not better than any other type of antenna! So if you have the space to set up a Half wave dipole why not consider a loop, and even if you don't have allot of extra space, you might consider the loop to be a very good alternative to the dipole.
What makes the loop different is that it creates a radiation field pattern that is the same as a dipole, but the field "lines" are magnetic, not electric. A radio wave is two fields, one electric and one magnetic, oscillating at 90 degrees to each other. A circulating flow of electrons, which produces the transmission pattern for a magnetic field, can radiate just as effectively as its electric field counterpart. | 
