Types of Satellite Orbits
Circular Orbit—an orbit whose altitude from the earth remains constant; it makes a circle that has the center of the earth as a center.
Elliptical Orbit—an orbit whose altitude from the earth varies from one extreme to another; it makes an ellipse with the center of the earth as one focus. The orbit’s lowest altitude is called the perigee, its highest altitude is called the apogee.
Equatorial Orbit—an orbit in the plane of the earth’s equator.
Polar Orbit—an orbit in a plane formed by the North and South Poles.
Synchronous Orbit—an orbit whose period is 24 hours, the same as that of the earth revolving on its axis—so that the satellite’s and the earth’s angular velocities are the same. Although there are many possible kinds of synchronous orbits, each must have an average altitude above the earth’s surface of approximately 22,300 statute miles.
Stationary Orbit—an orbit that is circular, equatorial, and synchronous—so that the satellite will appear stationary from any point on the earth.
Inclined Synchronous Orbit—an orbit that is synchronous but not stationary, since it does not follow the plane of the equator. From a point on earth, it will appear to follow a figure eight pattern about a line of constant longitude.
part 2
Satellite Communications Case Histories
