Design Your Own Dipoles And Inverted Vees

Most people are familiar with the center fed, half wave dipoles and inverted Vees that are so very popular. But did you know that there really is no exact formula for computing the length of these antennas? The problem is that there are several factors that affect the resonant frequency of any antenna (including these two types.) Some of these factors are: 

1. The height above ground
   
2. The diameter of the wire
   
3. Nearby structures
   
4. The affects of other antennas in the area and even the conductivity of the soil.

If you've ever played around with some of the antenna design programs you may realize that the formula for these types of antennas vary from about 476/f MHz. to 490/f MHz. depending on the band and the height above ground!

Fortunately there is a standard formula that can be used as a starting point in your design. For a center fed, wire dipole, this formula is 468 / frequency in megahertz. Although, at my location I've Always have had to shorten the antenna in order to obtain a 1:1 match.

At least in theory, an inverted Vee should be about 5% shorter than a dipole at the same frequency.

This page uses the standard formula, 468 / f MHz to calculate dipole lengths. You may change this number if you feel you know a better number to use as a starting point.