Connector
Understanding RF Connectors
RF connectors must maintain a precise 50-ohm (or 75-ohm) impedance match across their entire operating frequency range. Even small dimensional variations create impedance discontinuities that cause reflections. As frequency increases, connector tolerances become tighter and connector interfaces become smaller.
Common Connector Types
| Type | Impedance | Frequency | Coupling |
|---|---|---|---|
| BNC | 50/75 ohm | DC - 4 GHz | Bayonet |
| SMA | 50 ohm | DC - 18 GHz | Threaded |
| Type N | 50/75 ohm | DC - 18 GHz | Threaded |
| 3.5mm | 50 ohm | DC - 34 GHz | Threaded |
| 2.92mm (K) | 50 ohm | DC - 40 GHz | Threaded |
| 2.4mm | 50 ohm | DC - 50 GHz | Threaded |
| 1.85mm (V) | 50 ohm | DC - 67 GHz | Threaded |
| 1.0mm (W) | 50 ohm | DC - 110 GHz | Threaded |
Frequently Asked Questions
What is the best RF connector?
There is no single best connector; the choice depends on frequency range, power handling, and application. SMA is the most common general-purpose connector (DC-18 GHz). For higher frequencies, use 2.92mm (40 GHz), 1.85mm (67 GHz), or 1.0mm (110 GHz).
Are SMA and 3.5mm connectors compatible?
Yes, SMA and 3.5mm connectors are mechanically compatible and can be mated without an adapter. The 3.5mm interface is the precision version of SMA, with tighter tolerances that enable operation to 34 GHz vs 18 GHz for standard SMA.
How do you torque an RF connector?
Use a calibrated torque wrench set to the manufacturer-specified torque: 5 in-lbs for SMA, 12 in-lbs for Type N. Under-torquing causes intermittent contact; over-torquing damages the connector. Always hold the connector body with a wrench while torquing the nut.