Why do GPS satellites use helical antennas?

GPS satellites utilize helical antennas primarily because the signals they transmit are circularly polarized. This type of antenna allows the signals to maintain their integrity and reliability as they travel through various atmospheric conditions and undergo reflections from surfaces on Earth. Circular polarization is particularly advantageous for satellite communication because it minimizes the effects of multi-path interference, which occurs when signals bounce off buildings, ground, or other obstacles before reaching the receiver.

By using circularly polarized signals, GPS systems can ensure that the receiver can accurately interpret the signal regardless of its orientation, thus improving overall positioning accuracy. This is especially critical for GPS applications, where precise location data is essential.

The other options touch on important characteristics of GPS systems or antennas but do not directly explain the primary reason for using helical antennas in satellites. While better omni-directional receiving qualities and a larger radiation angle may be beneficial, it is the circular polarization that fundamentally underpins the design choice. Neutralizing ionospheric delay is more related to signal processing techniques rather than the antenna design itself.