If you are like me and have had a nanoVNA in the desk drawer and haven't thought to upgrade the firmware since you got it, there's good news. The latest version I found for my nanoVNA-F does port extensions! If you like to test reactive components at a given frequency before using them in a circuit, this kicks butt! It's also really handy when you calibrate to the end of the coax then connect that coax to an antenna. You can extend the reference plane past the connector and see whats happening at the feed point much more accuracy.