This invention is transmission line of system one kind of horizontal polarization electromagnetic field, is connects a hanging rectangular upper-frame by the plural number prop, as soon as turns round meets firmly in various props bottom end extends the foundation, establishes the side bar group which respectively in the fore-mentioned upper-frame relative both sides department above the one, under the side bar links up, each under side bar is the contact in a common ground plate, is equipped with mobile type of radiation board on an engagement fore-mentioned side bar in the fore-mentioned rectangular upper-frame, when this radiation board puts in the first position, but with ground plate parallel time, is may establish a perpendicular polarization electric field; , the radiation board puts in the second position is vertical relatively to the ground plate, is may establish a horizontal polarization electric field.