11/08/2026
A longwire HF antenna is a simple wire antenna designed for transmitting and receiving high-frequency (HF) radio signals. The main radiating wire is approximately 125 ft (38.1 m) long and is supported between a 26–33 ft (8–10 m) mast and a smaller 6.5 ft (2 m) support. A 1:4 UNUN matching device connects near the feed point to help transform the antenna’s impedance for use with 50-ohm coaxial cable. The coax runs down to the transceiver. The antenna wire should be kept as high, straight, and clear of nearby objects as practical. Its length can be adjusted to obtain better SWR on the desired operating frequency. Because the antenna is unbalanced, RF current can flow back on the coax shield. A 1:1 current balun/choke at the transceiver can help reduce unwanted common-mode RF. The actual antenna performance depends on frequency, wire length, height, ground conditions, and surrounding objects.
