Quick Answer
RHCP and LHCP are circular polarisation types for FPV antennas. RHCP (Right-Hand Circular Polarised) is the standard for most FPV setups, offering excellent resistance to multipath interference. LHCP (Left-Hand Circular Polarised) is used for specific applications like indoor flying or when interference requires polarisation switching. Always match your VTX and receiver antennas to the same polarisation type for optimal video signal.
Understanding Antenna Polarisation
Antenna polarisation refers to the orientation of radio waves as they travel through the air. For FPV video at 5.8GHz, circular polarisation is the dominant standard. Circular polarised antennas transmit radio waves in a spiral pattern rather than a linear plane. This spiral can rotate clockwise (RHCP) or anticlockwise (LHCP). Think of it like water swirling down a drain in two directions.
The key advantage of circular polarisation is its resilience to multipath interference. When your video signal bounces off buildings, trees, or the ground, those reflected waves reverse their polarisation direction. A linear polarised antenna would receive these reflections with degraded signal quality. Circular polarised antennas filter out much of this reflected noise because the antenna pattern is less affected by polarisation reversal.
However, circular polarisation has one critical rule: both your VTX antenna and your receiver antenna (on your goggles or ground station) must use the same polarisation. An RHCP VTX paired with an LHCP receiver will suffer significant signal loss, typically 20-30dB reduction. This is because the spiral patterns are rotating in opposite directions, cancelling each other out.
RHCP vs LHCP: When to Use Each
RHCP is the standard for outdoor FPV flying. Most commercial VTXs, receivers, and antennas are shipped as RHCP by default. It performs well in open environments like race tracks, freestyle spots, and long-range flights. The TrueRC Singularity antennas, for example, are available in both RHCP and LHCP versions, but the RHCP variant sees far more use in the FPV community.
LHCP finds its niche in specific scenarios. Indoor FPV pilots often switch to LHCP because it can perform better in environments with specific interference patterns. Some pilots also carry both RHCP and LHCP antennas to swap between them if they encounter signal issues on their frequency.
Signal Loss and Polarisation Mismatch
When polarisation is mismatched between transmitter and receiver, your video signal degrades dramatically. A 25mW VTX with mismatched polarisation might look like 5mW or less from the receiving end. You will see increased static, dropouts, or complete signal loss even at short range.
The good news is this problem is easy to diagnose and fix. If you suddenly lose video signal at a range where it previously worked, check that both antennas are the same polarisation type. Most antennas are clearly marked with RHCP or LHCP labels near the connector. Swap in a matched pair and your signal should return immediately.
Choosing the Right Antenna
Selecting antennas involves more than just polarisation. Consider gain, beam width, and durability alongside RHCP vs LHCP. The TrueRC Matchstick offers a balance of compact size with solid performance for general flying. Stubby antennas like the Singularity protect against crashes whilst maintaining decent range.
Your choice depends on flying style. Racing pilots often prefer higher gain, narrower beam width antennas for punch through obstacles. Freestyle pilots might choose wider beam width for better coverage around the drone. Long-range setups typically use directional antennas on both VTX and receiver for maximum distance. Check our FPV video systems collection for antenna options matching your needs.
Remember that antenna quality matters more than the polarisation choice itself. Well-made RHCP antennas from reputable brands will outperform poorly manufactured alternatives, regardless of whether they are RHCP or LHCP. For more guidance on antenna selection, see our complete antenna buying guide.
FAQ
Q: Can I mix RHCP and LHCP antennas?
A: No, mixing polarisation types causes significant signal loss, typically 20-30dB reduction. Always match your VTX and receiver antennas to the same polarisation type for optimal video quality.
Q: Which polarisation is better for racing?
A: RHCP is the standard for outdoor FPV racing. Nearly all commercial racing VTXs, receivers, and antennas ship as RHCP by default. Use LHCP only if you have specific interference reasons to do so.
Q: Why does my video signal improve when I change antenna orientation?
A: Antenna orientation affects signal strength due to the radiation pattern of circular polarised antennas. Experiment with rotating your antenna to find the position that gives the cleanest video signal in your specific environment.