For model aircraft requiring real-time control, relying on any radio characteristics to increase distance is unreliable except for directly receiving signals. Although long-wave and medium-wave diffraction capabilities are extremely strong, they are still constrained by the spatial environment and are very unstable.
Omnidirectional Antenna: Often called a whip antenna in radio engineering. Like a light bulb, its transmission range, when placed vertically, scatters horizontally in all directions, providing a uniform field strength distribution within a 360-degree range. This is a commonly used type. When placed horizontally, if the antenna is oriented east-west, the field strength distribution includes the north-south direction (including the sky) and the north-south direction from the antenna to the ground. Therefore, vertical antennas are mainly for horizontal targets, while horizontal antennas are mainly for targets at vertical height and for horizontal targets within a narrow range.
Yagi Antenna: A directional transmission antenna. A Yagi antenna consists of a director (slightly shorter than the antenna) and a reflector (slightly longer than the antenna), with the antenna mounted in the middle. The field strength of a Yagi antenna is mainly concentrated on the director side. The reflector reflects the signal emitted by the antenna back towards the director, increasing the field strength and also shielding against interference from behind. When vertically mounted, the vertical field strength distribution angle of a Yagi antenna is similar to that of an omnidirectional antenna. The horizontal field strength distribution angle depends on the number of directors; more directors result in a smaller angle, stronger directivity, and higher field strength within the angle. Generally, 3-5 directors are common; more than that has little effect. Its main characteristics are uniform field strength distribution within the effective range, good directivity, and strong anti-interference capability.
Parabolic Antenna: The field strength distribution of this type of antenna has two parts, similar to a flashlight beam. One part is the scattered light directly emitted by the bulb, and the other, and the main part, is the direct light reflected by the reflector. Therefore, parabolic antennas have the highest efficiency, but also the strongest directivity. They are most commonly used in fixed point-to-point microwave communication. If used for communication on aircraft, they must be mounted on a high-precision tracking gimbal; otherwise, the antenna will be ineffective. Furthermore, parabolic antennas require very high assembly precision.
Planar Antennas: The characteristics of planar antennas are basically the same as Yagi antennas. Good planar antennas have a more complex structure, but are small in size, lightweight, and easy to install. They have a high volumetric efficiency ratio, making them the preferred antenna for FPV enthusiasts in the field. They require the use of a tracking gimbal.
