If you’re into FPV drones, you’ve probably heard about LHCP (Left-Hand Circular Polarization) and RHCP (Right-Hand Circular Polarization). These terms describe how the radio waves from your antennas rotate as they travel through the air. Most of the time, you’ll want to stick with one type of polarization for all your antennas—either LHCP or RHCP. But there’s one specific situation where mixing polarizations can actually work in your favor. Let’s break it all down, including that special case, so you can get the most out of your FPV setup.
What Is Circular Polarization?
First, let’s quickly recap what circular polarization is. When we talk about LHCP and RHCP, we’re talking about the direction in which the radio waves spin as they move through the air. LHCP spins counterclockwise, and RHCP spins clockwise. This spinning helps reduce interference, especially in environments where signals bounce off surfaces like trees, buildings, or the ground.
The general rule is simple: if your transmitter antenna (on your drone) and your receiver antenna (on your goggles or ground station) use the same polarization, they’ll work together perfectly. But if they’re mismatched—say, LHCP on the drone and RHCP on the goggles—you’ll get a weak or nonexistent signal. That’s because circularly polarized antennas are designed to reject signals with the opposite polarization.
Why Circular Polarization Rocks for FPV
Circular polarization is a game-changer for FPV drones because it helps cut down on multipath interference. This is when your video signal bounces off surfaces and creates ghost signals that mess with your video feed. By using LHCP or RHCP, you can filter out these reflected signals and enjoy a cleaner, more stable video feed.
When Should You Mix LHCP and RHCP?
Now, here’s where things get interesting. While you should almost always match your antennas’ polarization, there’s one specific situation where mixing LHCP and RHCP can actually improve your setup: when using a helical antenna on a reflector.
The Helical Antenna on a Reflector Setup
A helical antenna is a type of directional antenna that’s great for long-range FPV flying. It’s often paired with a reflector (a flat or curved surface behind the antenna) to boost its performance. Here’s the trick: when you mount a helical antenna on a reflector, the reflector can reverse the polarization of the signal. For example, if you use an RHCP helical antenna, the reflector might flip the signal to LHCP.
To account for this, you’ll want to use the opposite polarization on your helical antenna compared to the rest of your system. Here’s how it works:
- If your system uses RHCP: Use an LHCP helical antenna on the reflector. The reflector will flip the signal back to RHCP, matching the rest of your setup.
- If your system uses LHCP: Use an RHCP helical antenna on the reflector. The reflector will flip the signal back to LHCP, keeping everything in sync.
This setup ensures that your helical antenna works seamlessly with the rest of your FPV system, even though you’re technically mixing polarizations.
Why Does This Work?
The reflector acts like a mirror for your signal. Just like a mirror flips your reflection, it flips the polarization of the signal. By intentionally using the opposite polarization on your helical antenna, you’re compensating for the reflector’s effect. This way, the signal that reaches your receiver matches the polarization of your other antennas, giving you the best possible performance.
When Should You Use This Setup?
This trick is especially useful for long-range FPV flying, where directional antennas like helicals are a must. If you’re building a ground station with a helical antenna and a reflector, mixing polarizations can help you get the most out of your setup. Just remember: this is the only situation where mixing LHCP and RHCP makes sense. For all other parts of your FPV system, stick with the same polarization.
LHCP vs. RHCP: Which Should You Choose?
If you’re not using a helical antenna with a reflector, the choice between LHCP and RHCP comes down to a few factors:
- What Are Other Pilots Using? If you fly with a group, it’s a good idea to match their polarization to avoid interference.
- Availability of Gear: RHCP is more common, so it’s easier to find compatible antennas and equipment.
- Personal Preference: If you’re flying solo or in an area without many other pilots, you can choose whichever polarization you like. Both LHCP and RHCP perform equally well in reducing interference.
Why Our Antennas Are a Great Choice
At prodrone.pl, we know how important it is to have reliable antennas for your FPV setup. That’s why we offer both LHCP and RHCP antennas, all perfectly tuned to the 5.8 GHz frequency range. Whether you’re flying with a digital or analog system, our antennas are designed to deliver the best possible performance, with wide usable bandwidth and excellent signal clarity.
Conclusion: LHCP and RHCP Are Both Great—But Know When to Mix
For most FPV setups, sticking with one type of polarization—either LHCP or RHCP—is the way to go. But if you’re using a antenna with a reflector, mixing polarizations is only way for your performance. By understanding how LHCP and RHCP work, and when to break the rules, you can build an FPV system that delivers crystal-clear video, no matter where you’re flying.