NanoVNA

The NanoVNA is a tiny, self contained, portable, but low cost Vector Network Analyzer.  It features a touch screen and built in lithium rechargeable battery.

NanoVNA with included accessories (minus SMA to UHF adapter).

Of interest to the radio operator is being able to measure reflected power and calculate the Standing Wave Ratio (SWR) over a frequency range.  The NanoVNA automates this resulting in an easy-to-interpret graphical summary of antenna radiation efficiency vs. frequency. 

Hooked up to the Firestik 2MCKB 2m antenna. 

Triangle "1" at 143.400 MHz showing 1.05 SWR.  Should work well on the 2m band 144-148 MHz.

This information is crucial for effective antenna building or diagnosing and many antennas can be adjusted to improve SWR around a desired frequency.