Video Systems: Antennas And Goggles
Range is achieved in an FPV setup through a combination of transmission power (in mW) and antennas, with surprising weight on the latter. Antenna choice determines the form the radio wave takes. Generally, you're choosing between linear and “right-hand circular polarized” (RHCP or just CP). A circular polarized setup reduces interference caused by multipathing. In the same way that polarized sunglasses block reflected light, a polarized radio setup blocks signals that have “bounced”, and be arriving later than intended.
Secondly, antennas are either omni-directional or directional. This is fairly self-explanatory. Directional antennas come in different forms (such as Yagi, patch, helical), and have different levels of directionality, measured in decibels. Directional antennas are used at the receiver, not the transmitter.
The higher the dB of an antenna, the more directional it is. Directional antennas must obviously be pointed towards the craft at all times, which can limit flying options. Antenna trackers can be used to automatically pan and tilt the antenna towards the rig using telemetry data, but this is a premium optional extra.
Just as important as transmitters (shortened to Tx) are receivers (Rx). There is relatively little difference between receivers, although some are fitted with tuned filters to reduce interference bleed from other frequencies. Be sure to double-check that your receiver's channel mappings match the transmitter. As we'll see next, receivers can also be built into display devices.
The last critical piece of your FPV setup is a display, which can either be a monitor or goggles. PC displays will work, though there are also video stations specifically for hobbyists, too.
FatShark is the big name in FPV-specific video goggles. The company's Dominator model (soon to be replaced by the higher-resolution Dominator V2) is a near faultless system, with module bays for head-tracking or built-in receivers, if required.
The advantage of goggles over a monitor is total immersion. Good goggles block outside light, so regardless of the sun's brightness, the image you see is easily visible and free from glare. The experience is similar to watching your flight from the middle row of an empty movie theater.