What Mates With What

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The outer conductor size of these connectors prevents the mating of incompatible connectors. Connectors in each of the shaded areas below have the same size outer conductor and therefore can safely be mated together.

However, damage to connectors occurs from wear, lack of cleaning, improper connection techniques, and poor handling techniques. When mated, a damaged connector can cause another connector to also become damaged. Therefore, clean and inspect all connectors before mating.

In addition, up to three different grades in each connector type are usually available. Production grade connectors can damage metrology grade connectors when mated. Learn more about connector grades.

The first five connector types in the table below use an air dielectric. The name of a connector (ex: 1.85) is determined by the diameter of the air dielectric. This, along with the notes in the following table, is the easiest way to identify these connector types.

NMD style connectors are precision and also rugged. The NMD connector uses a larger outer mechanical interface to provide a stable connection at the front panel. They are typically used to connect with the VNA test port connectors as connector savers. NMD connectors mate exactly like their non-NMD equivalents.

Connector Type



Mates with...


1.0 mm

To 110 GHz

1.0 mm

Much smaller connector than any of those below.

1.85 mm

To 70 GHz

2.4 mm

The outer thread size of the 1.85 and 2.4 connectors is bigger than SMA, 3.5, and 2.92. This makes the area of the outer conductor mating surface look very large compared to the relatively small air dielectric.

2.4 mm

To 50 GHz

1.85 mm

The 1.85 mm connector that is manufactured at Keysight has a groove in the male nut and female shoulder to distinguish these two connector types.


2.92 mm

To 40 GHz

3.5mm and SMA

These two connectors use the same center pin.


3.5 mm

To 34 GHz

2.92 mm and SMA


To 24 GHz

2.92 mm and 3.5 mm

Uses a PTFE dielectric.

Note: SMA connectors are a common and inexpensive type, but their lack of precision affects their durability and performance, and can cause increased wear when mated with other (precision) connectors. SMA connectors are only rated for a very limited number of connection cycles and should be examined before each use.