A (Medium Earth Orbit) satellite's orbiting height can range from a few hundred miles to a few thousand miles above earth. It is not the the lowest orbiting satellite but it is definitely not as high as a standard
geostationary satellite. MEOs fly in both near circular orbits and in elliptical ones. For an elliptical orbit, the
perigee is it's lowest altitude, and the
apogee is it's greatest. This change in altitude causes it to change speed a lot. It's speed is the greatest when it is near perigee. The circular orbit satellite flies at a near constant height so it's speed is also constant. A satellite near perigee can cross the sky in just a few minutes while one near apogee can take hours.
MEOs seem to be one of the most efficient satellites. They have more
coverage than
LEOs (Low Earth Orbit) so you need many less satellites to make a a network that provides global coverage and they are lower than standard satellites so you can use much smaller, less powerful antennas to access them.
thanks to:
http://www.whatis.com