Quick Answer
FPV antennas use four connector types: SMA, RP-SMA, MMCX, and U.FL. SMA and RP-SMA are threaded and durable but bulky. MMCX is a snap-on connector found on most modern flight controllers. U.FL is tiny and soldered to the board. Mixing up SMA and RP-SMA is the most common mistake we see, and it means your antenna simply won't work.
Why Connector Type Matters
Last month we had three customers order the wrong antenna connector. One built a beautiful 5-inch freestyle quad over two weekends, powered it up, and got a blank screen. The antenna didn't fit the VTX. Two weeks of building, thirty seconds to discover the mistake.
The connector must match your VTX or flight controller. The industry has mostly standardised on MMCX for on-board VTX connections and SMA for goggles receivers. But SMA and RP-SMA look nearly identical, and mixing them up is easy. We've done it ourselves on the workbench.
SMA vs RP-SMA: The Trap Everyone Falls Into
Both are threaded metal connectors about 10mm across. The difference is which part has the centre pin:
- SMA: The plug (cable side) has the pin. The jack (device side) has a hole.
- RP-SMA: Reversed. The jack has the pin, the plug has the hole.
Screw an SMA antenna onto an RP-SMA VTX and you get no electrical contact. Zero signal. We stock both 45 Degree SMA Connectors and 45 Degree RP-SMA Connectors precisely because this distinction catches people out every week.
Most 5.8GHz video transmitters use SMA. Some older FPV gear and radio receivers use RP-SMA. The TBS Unify Pro, for example, uses SMA. The Eachine EV800D goggles use RP-SMA. Always check your VTX datasheet before ordering from our antenna collection.
MMCX: The Modern Standard
MMCX (Micro-Miniature Coaxial) is a small snap-on connector about 3mm across. Almost every modern flight controller with a built-in VTX uses it. It clicks on and off for quick swaps but can pop off in a crash.
Two problems we see in repairs: connectors detaching mid-flight after impact, and the gold centre pin bending after too many cycles. The fix is a dab of hot glue or a zip tie. We do this on every build that leaves our workshop.
U.FL: Tiny, Fragile, and Semi-Permanent
U.FL connectors are roughly 2mm across, soldered directly to the board. You'll find them on ELRS receivers, GPS modules, and micro whoop flight controllers.
U.FL saves weight but breaks easily. Rated for about 30 mating cycles (versus 500+ for MMCX), and the coaxial cable frays after bending. A U.FL connector weighs roughly 0.1g versus 0.5g for MMCX. On a 20g whoop, that matters.
We treat U.FL as semi-permanent. Once plugged in, it stays. For micro drones, U.FL is the only option. For anything 3-inch or larger, pick MMCX.
What We'd Actually Use
- 5-inch freestyle/racing: MMCX from FC to antenna base, then SMA for the antenna. The FlyFishRC Osprey SMA antenna is our standard VTX antenna.
- Long-range (7-inch+): Direct SMA from VTX to antenna. No adapters, no extra failure points.
- Micro/whoop: U.FL throughout. Weight overrides durability.
- Goggles: SMA or RP-SMA depending on the model. The 4-Lobe Cloverleaf SMA antenna works with most analog goggles.
Always match impedance. All FPV antenna connections are 50 ohm. WiFi antennas are often 75 ohm and will cause signal reflections. See our antenna buying guide and RHCP vs LHCP polarisation guide for more.
FAQ
Q: Can I use an SMA to RP-SMA adapter?
A: Physically yes, but each adapter adds a failure point and a small amount of signal loss. Buy the right antenna instead.
Q: How do I tell SMA from RP-SMA?
A: Look at the centre of the connector on the device. If there's a pin sticking up from the middle, it's RP-SMA. If it has a hole, it's SMA. Use a torch.
Q: Is MMCX durable enough for racing?
A: Yes, if you secure it. A bare MMCX pops off in the first hard crash. Hot glue or a zip tie over the connector makes it race-proof.
Q: Why does my antenna keep falling off?
A: If it's MMCX, that's a safety feature (it releases before the PCB trace tears). Secure it with hot glue. If it's SMA, check you're threading it fully. See our antenna placement guide for mounting tips.
Q: What connector does my ELRS receiver use?
A: Most ELRS receivers use U.FL for the antenna connection. Some larger models with external antennas use IPEX4, which is mechanically compatible.