Geostationary satellites are in a circular orbit high above the equator (approx 22500 miles). If you are observing the string of satellites from the equator, they would be in a straight line. If you observe from a higher latitude (say 45 deg N) you see the circle of orbit from an angle. It appears as an ellipse. The part you can see is of course a part of the ellipse. A satellite that is due south of you would be high in the sky while one located west of you might be close to the horizon. The polar mount tips the telescope or dish up and down as you turn it east/west thus tracking along the polar arc. Note that the exact shape of the polar arc depends on your latitude. A polar mount adjusted for use in Minnesota will not track properly from Florida.