Leg Lengths: Inverted V vs Horizontal Dipole Antennas
The halfwave dipole antenna element lengths are measured differently when building an inverted V dipole. You usually make an inverted-V dipole slightly shorter than a flat horizontal half-wave dipole because the downward-sloping legs change the antenna's capacitance and feed point impedance. A common rule of thumb is: Horizontal half-wave dipole: Each leg: Inverted-V dipole: Start with 2–5% shorter than the horizontal calculation, then trim while checking resonance. A practical formula is: or Example: 20 meters (14.2 MHz) Horizontal dipole: Total: Each leg: Inverted V: Total: Each leg: That's about 3.4 inches shorter per leg . Why? When the legs slope downward: The ends are closer to ground. The antenna has greater end capacitance. It becomes electrically longer than the same physical wire length. Therefore, less wire is needed to resonate at the same frequency. ...