An end-fed half-wave antenna (EFHW) has a very high feed point impedance. What device could be used to provide a good match to 50-ohm coaxial cable?

An end-fed half-wave (EFHW) antenna is fed at the point where the voltage is highest and the current is lowest, which creates a very high feed point impedance, typically in the range of 2000 to 3000 ohms. To connect this to a standard 50-ohm coaxial cable, you must match these vastly different impedances. A transformer is the ideal device for this job. Commonly referred to as an 'unun' (unbalanced to unbalanced), an impedance matching transformer with a high ratio, such as 49:1 or 64:1, steps down the high impedance of the antenna to perfectly match the 50-ohm impedance of the transceiver and coax. While a good ground or a counterpoise is necessary for the overall efficiency and to handle return currents, they do not perform the primary impedance transformation required to match 3000 ohms to 50 ohms.