Pointing errors are more detrimental for which type of SATCOM antenna?

• A. Dipole
• B. Broad-beam
• C. Isotropic
• D. Narrow-beam, high-gain

Answer: (D)

In SATCOM, the tighter an antenna’s beam, the more sensitive it is to pointing errors. A narrow-beam, high-gain antenna concentrates most of its radiated and received energy into a very small angular region. If the antenna isn’t pointed very precisely at the satellite, the satellite’s signal can fall outside the main lobe, causing a large drop in received power and link performance. Tracking systems in ground stations are therefore essential for these high-gain dishes to maintain the connection.

In contrast, dipoles and broad-beam antennas spread energy over wide angles, so small mispointings don’t knock the signal out of a concentrated beam to the same degree. An isotropic radiator has no preferred direction, so pointing accuracy isn’t as critical in the same way. Hence, pointing errors cause the greatest effect on a narrow-beam, high-gain antenna.