Coaxial Connector
Understanding Coaxial Connectors
Coaxial connectors are the most common RF interface. Choosing the right connector for the application is critical. Each connector type has specific frequency, power, and mechanical characteristics.
Common RF Connectors
| Type | Freq Range | Impedance | Mating |
|---|---|---|---|
| BNC | DC-4 GHz | 50/75 ohm | Bayonet |
| SMA | DC-26 GHz | 50 ohm | Threaded |
| N-type | DC-18 GHz | 50/75 ohm | Threaded |
| 3.5mm | DC-34 GHz | 50 ohm | Threaded |
| 2.92mm (K) | DC-40 GHz | 50 ohm | Threaded |
| 2.4mm | DC-50 GHz | 50 ohm | Threaded |
| 1.85mm (V) | DC-67 GHz | 50 ohm | Threaded |
| 1.0mm (W) | DC-110 GHz | 50 ohm | Threaded |
Frequently Asked Questions
What coaxial connector should I use?
Below 4 GHz: BNC (quick-connect) or N-type (rugged). Below 18 GHz: SMA or N-type. Below 26 GHz: SMA. Below 40 GHz: 2.92mm (K). Below 67 GHz: 1.85mm (V). Below 110 GHz: 1.0mm (W). Choose based on frequency, power, and application.
Are SMA and 3.5mm compatible?
Yes. 3.5mm connectors are mechanically compatible with SMA. However, SMA has a Teflon dielectric that limits it to 26 GHz, while 3.5mm uses an air dielectric for 34 GHz operation. Mating SMA to 3.5mm is acceptable up to 18 GHz.
How do I maintain connector performance?
Use a torque wrench (SMA: 5 in-lbs, N: 12 in-lbs). Inspect connectors with a gage pin and magnifier before mating. Clean with isopropyl alcohol. Never force misaligned connectors. Damaged connectors degrade return loss and can damage mating connectors.