ANTENNAS AND FREQUENCY BANDS FOR DEEP SPACE APPLICATIONS
Antennas for Deep space applications require special importance and considerations for designing them. Deep Space applications missions include Satellites, rovers, and landers.
A planetary mission includes multiple phases:
- Launch phase
- Cruise phase
- Entry, Descent, and Landing
- Surface operations
The design and frequency considerations would be different for different stages.
During Launch phase:
A low gain, broad beam antenna is required during the launch phase to cover maximum area and to avoid precision of the antenna. Microstrip antennas, dipole, and monopole antennas are preferred for these applications.
During Cruise phase:
A medium or high gain antenna is preferred once the spacecraft reaches far away from Earth to compensate for the path loss. Gimbaling of the antenna is required to point the antenna to Earth.
During the operation phase:
Multiple antennas with different gains are required during this phase to meet various purposes. For Telemetry: Low gain antenna is preferred as it consumes very little power. In general, telemetry data is transmitted to the Orbiter which then relays the information back to Earth. These applications use broadband antennas like Monopole, Dipole, etc. as they offer high beam width and near Omnidirectional pattern.
For Direct to Earth communication: High gain, X band frequency antenna is preferred for this purpose. Gimbaling should be done to maintain the Line of sight. A microstrip patch array antenna is generally preferred for these applications as they offer lightweight and high gain.
Frequency bands:
The choice of frequency band depends on the system with which we need to establish the link (like orbiters or Direct Earth Link etc.).
Launch phase: S or X band telemetry is widely used.
Entry Descent and landing: X band or Ka-band for Direct to Earth communication. For relaying through satellite, the UHF band is preferred.
For Surface to Low orbiter links: UHF frequency for Telemetry and X band frequency for data transfer.
Surface to Areostationary links: S-band for telemetry and X band for data transfer.
Mars Ascent vehicle communication: UHF band with wide beam width antenna is most suitable.
