Inverted Vee Antenna
A proven wire antenna for the HF bands is the Inverted Vee antenna. It is essentially a modification of the dipole that requires only a single mounting point. Because the arms form an angle of approximately 100–120 degrees, the impedance is lower than that of a dipole, allowing for better matching to 50-ohm coaxial cable. Another advantage is the presence of a vertical component in the radiation pattern, which is beneficial for DX contacts.
To build it, you’ll need wire of sufficient strength (1.5 mm in diameter or more), a center insulator with a connector for attaching the coaxial cable, two end insulators, some insulating cord, and a suitable support—a tree. From the wire, we’ll construct a half-wave dipole, the length of which we’ll calculate using the formula
lambda = 300/f
[m; MHz]
dipole = lambda/2[m; m]
dipole arm = (dipole/2) × 0.96 [m; m]
The last formula includes the constant 0.96—the shortening factor. Due to the thickness of the antenna wire and the surrounding environment, the practical length of the arms is shorter than the theoretical length. After constructing the antenna, we raise it to the operating height—for example, using a pulley—and check its tuning with a meter or an antenna analyzer. The ideal operating height is lambda/4 or greater.