WiFi Antenna Cables: SMA, RP-SMA, N-Type — Complete Guide

Ordering the wrong connector type is the single most common mistake in WiFi antenna cable purchases. RP-SMA and SMA look identical in photos. N-type and RP-SMA look vaguely similar at a glance. But none of these three will mate with each other. Getting the connector type right is the first step, and the rest of this guide covers loss calculation, cable selection, and weatherproofing outdoor installations.

RP-SMA: The Consumer and Prosumer WiFi Standard

Virtually every consumer and prosumer WiFi router and access point uses RP-SMA (Reverse Polarity SMA) on its external antenna ports. This includes Asus, Netgear, TP-Link, most Ubiquiti UniFi models, and most aftermarket routers running OpenWrt. The RP-SMA female connector on the router has a small center pin; the mating RP-SMA male connector on an antenna or cable has a center socket. This is the reverse of standard SMA, which is why it's called "reverse polarity."

To identify RP-SMA: look into the port on the router. If you see a small pin protruding from the center (surrounded by threads), it's RP-SMA female. The cable end that connects to it must be RP-SMA male (with a center socket).

RFC195 RP-SMA to RP-SMA Cable  |  RFC240 RP-SMA to RP-SMA Cable

SMA: Lab Gear, SDRs, and Professional APs

Standard SMA is used on laboratory equipment, SDR receivers, GPS modules, LTE/cellular modems, and some professional-grade access points. Standard SMA male has a center pin; standard SMA female has a center socket. If you look into a standard SMA female port and see a socket (recessed hole), it's standard SMA, not RP-SMA.

N-Type: Commercial and Outdoor Installations

N-type is the standard connector on outdoor access points and antennas used in commercial deployments. Cambium Networks PMP series, Ubiquiti Rocket M and PowerBeam series, outdoor yagi and panel antennas, and cellular equipment all use N-type. It's a 21mm-diameter threaded connector rated to 11 GHz, IP67 weatherproof when mated, and handles 500W continuously at 1 GHz. It's significantly larger than SMA and RP-SMA.

RP-TNC: Legacy Cisco Aironet and Linksys

Older Cisco Aironet access points and Linksys WRT series routers (including the iconic WRT54G) used RP-TNC connectors. RP-TNC is the same reverse-polarity concept applied to the larger TNC connector body. If you're working with legacy Cisco wireless gear, verify you have RP-TNC before ordering — it won't mate with RP-SMA even though both have "RP" in the name.

RFC195 RP-TNC to RP-TNC Cable

Cable Loss at WiFi Frequencies

WiFi operates at 2.4 GHz, 5 GHz, and 6 GHz (WiFi 6E). Cable loss is significant at these frequencies, especially for longer pigtail runs. Here are representative figures per 10 feet:

Link Budget Example

A 5 GHz router with a +5 dBi external antenna connected via 15 feet of RFC195 cable loses approximately 1.35 dB in the cable. The antenna still provides +5 dBi of gain, so the net effective gain is about +3.65 dBi — the antenna is working at about 85% effectiveness. That's a perfectly acceptable result.

The same 15-foot run in RG58 loses about 3.15 dB at 5 GHz. The +5 dBi antenna is now working at only +1.85 dBi net gain — you've lost more than half the antenna's benefit to cable loss. For access points and WiFi bridge links where every dB of RSSI matters, RFC195 or RFC240 is the right choice for runs over 6 feet.

Best Practices for WiFi Antenna Cables

Keep pigtails (the short cables between the radio and an antenna or outdoor run) under 12 inches whenever possible. For any run over 15 feet going to an outdoor antenna, use RFC400 or LMR-400 — the thicker cables are worth the stiffness for outdoor installations. Do not coil excess cable: a coil of coax acts as an inductor and creates loss that isn't reflected in the per-foot spec. Buy the length you need and run it directly.

RFC195 N-Male to RP-SMA  |  RFC400 N-Male to RP-SMA  |  LMR-400 N-Male to RP-SMA

Weatherproofing Outdoor N-Type Connections

N-type connectors are rated IP67 when mated, but any outdoor connection that isn't sealed will eventually allow water ingress at the thread engagement point. For any outdoor WiFi installation, seal every N-type connection as follows: wrap the mated connector pair with two layers of self-amalgamating tape. Start 1 inch below the connector onto the cable, spiral upward with 50% overlap under slight stretch, continue over the connector body, then reverse direction back down toward the cable. This double-pass creates a watertight boot over the entire connection. Finish with a wrap of UV-resistant vinyl tape over the self-amalgamating tape to protect it from UV degradation.

Bulkhead Connectors for Wall Pass-Throughs

Routing a cable from an outdoor antenna through a wall into an indoor equipment rack requires a weatherproof wall pass-through. The correct approach is a bulkhead N-female connector mounted through the wall or enclosure. The outdoor side connects to the antenna cable (N-male). The indoor side connects to the run to the access point or router. For a WiFi access point with an RP-SMA port, you'd need an N-female bulkhead on the wall and an N-male to RP-SMA cable on the inside:

RG400 N-Female Bulkhead to RP-SMA  |  RG316 N-Female Bulkhead to RP-SMA

Need a specific length? Use the cable configurator to build any combination in any length. Ships next business day.