Part of our Building Your First Ham Radio Station guide.
One of the best things about the end-fed half-wave is how flexible it is. It is basically a long wire with a matching transformer at one end, which means you can hang it in whatever shape your location allows. The same antenna that works strung between two trees also works off a single support, off the side of your house, or off a fishing pole in a field. Here are the configurations worth knowing and what each one is good for.
Horizontal (flat top)
The classic setup is a straight horizontal wire, supported at both ends, with the transformer at one end and the wire running roughly level to a far support. When mounted a decent fraction of a wavelength up, a horizontal EFHW behaves a lot like a dipole. It tends to be quieter on receive and favors higher-angle radiation on the lower bands, which is great for regional contacts.
This is the go-to when you have two good supports, such as a pair of trees, and enough room to stretch the whole wire out straight. It is simple and it performs well.
Sloper
When you only have one high support, run the wire as a sloper. The transformer sits low, often near the ground or at the base of a mast, and the wire angles up to a single high point like a tree limb or the top of a mast. The reverse also works, with the feed point high and the wire sloping down.
A sloper gives you a mix of horizontal and vertical characteristics and a bit of directionality in the direction of the slope. It is a practical, common choice for backyards and portable sites where you can only get one end up high.
Inverted V and inverted L
If you can get the middle of the wire up high on a single central support, you can hang it as an inverted V, with both halves sloping down toward the ground on either side. This gives you a more omnidirectional pattern than a flat top and only needs one tall support in the middle.
The inverted L takes the wire up vertically for part of its length and then bends it to run horizontally. This is handy when you have limited horizontal room but some height available, and it produces a useful blend of low-angle vertical radiation and higher-angle horizontal radiation.
Vertical
Run the wire straight up a non-conductive support, such as a telescoping fiberglass mast or a fishing pole, and you have a vertical EFHW. This configuration favors low-angle radiation, which makes it a strong performer for DX, and it takes up very little ground space.
A full half-wave on the lower bands gets tall in a hurry (40 meters wants roughly 66 feet of wire), so a pure vertical EFHW is most practical on the higher bands. On lower bands, people often compromise by going part way up and then sloping the rest, which is really just an inverted L again.
Vertical on a mast with the wire zig-zagged
When the mast is not quite tall enough for the whole wire, a common trick is to run the wire up the mast as far as it will go and then route the remaining length back and forth or off at an angle. It is not textbook pretty, but the EFHW is forgiving, and this lets you fit a lower-band half-wave onto a shorter support. Expect a small hit to efficiency and pattern compared to a fully extended wire, but it gets you on the air.
A few things that apply to all of them
- A short counterpoise and a common-mode choke help keep RF off your coax no matter which shape you choose.
- Height matters. Getting the radiating wire higher and more in the clear almost always helps more than fussing over the exact shape.
- Because an EFHW is resonant on its half-wave band and its harmonics, one wire often covers several bands (for example a 40 meter EFHW also plays on 20, 15, and 10), which is a big part of its appeal for portable work.
- Keep the high-voltage far end away from anything people or animals can touch while you transmit.
The takeaway is that you do not need the perfect site to use an EFHW. Look at what supports you have, pick the configuration that fits, and get the wire as high and as in the clear as you can. That adaptability is exactly why this antenna lives in so many go-kits.