PL-259/SO-239 (UHF)
The most common connector on amateur and CB radios is the PL-259/SO239 connector. This is an old connector, coming from the 1930s/1940s. At the time, they were called UHF connectors. The PL-259 connector is the male end, while SO-239 is the female side.
These connectors work well for HF and VHF, but are a bit lossy at UHF frequencies.
N
This connector was developed in the 1940’s and was designed to handle UHF+ frequencies. It has less loss at these frequencies and is more common to find on higher-end VHF/UHF radios and microwave radios.
These connectors WILL NOT work with PL-259/SO-239 connectors. They are diffferent sizes.
SMA
This connector is common on handheld VHF/UHF radios and some SDR receivers. This connector is tiny!
Just be aware that some Baofeng/Chinese radios will use SMA male, and the antennas will be SMA female. While ICOM/Kenwood radios may use a female connector on the radio and a male on the antenna.
It is also common to get an adapter from SMA to PL-259/SO-239 and connect to a larger external antenna.
BNC
The BNC connector is a quick-connect, low-loss connector. They can be found on older handheld radios and test equipment, like oscilloscopes and RF signal generators. They are also common on audio applications.