Patch antennas: This is a relatively heavy, flat ceramic antenna that doesn't work well without a ground plane. In other words, it's not an antenna for drones or pedestrians; it's an antenna for car roofs or houses. This antenna doesn't filter reflected signals very well, but it typically has a small phase center variation (PCV), making it better for RTK. Having a ground plane means that a patch antenna won't receive reflected signals from below, but if tilted, the ground will be on the side, and reflected signals can be received. With the same quality, a patch antenna will be heavier and cheaper than a helix antenna.
Helix antennas: A spiral antenna, usually with four spirals. This is a lightweight antenna that effectively filters reflected signals without a ground plane. Before using it in RTK, it's recommended to check that the chosen antenna has a small phase center. It's suitable for anything that frequently tilts—drones, pedestrians, bicycles, especially if autonomous solutions with meter-level accuracy are needed. With the same quality, a helix antenna will be lighter and more expensive than a patch antenna.
Cross-dipole antennas: This type of antenna best filters reflected signals and provides more uniform reception of both low and high satellites. Its phase center size is usually larger than that of good patch antennas, but it's still suitable for RTK on a drone. An example of a rare antenna designed for a specific purpose is one that captures signals from satellites low on the horizon (up to 5 degrees from the horizon). The main downside of this type of antenna is that it's more expensive than patch and helix antennas with similar characteristics. However, if you need a lightweight (but pricey) antenna for RTK on a drone, this is the one to choose.
© Eltehs SIA 2023
