These adapters by Picotest are designed for RF, microwave, and millimeter wave applications.  
 
Support SI/PI and RF, insert specs for frequencies
 
This cased set contains:
x2 N(M)-BNC(F)
x2 N(M)-SMA(F)
x2 BNC(M)-SMA(F)
x2 SMA(F)-SMPM
 
Key Features
This adapter set is optimized to connect to SMPM probes. 
 
Frequency:
N(M)-BNC(F): 18 Hz
N(M)-SMA(F): 18 Hz
BNC(M)-SMA(F): 18 Hz
SMA(F)-SMPM: 26.5 Hz