Guidelines

# How do you determine dipole size?

## How do you determine dipole size?

Dipole length formula Often a formula for the length of a dipole in feet is seen as 468 / frequency. This can be derived by taking the figure of 492 seen in the formula above and multiplying it by the typical A or end effect factor of 0.95.

### Is a balun needed for a dipole antenna?

The use of a balun will prevent the coax radiating any power or picking up any noise. In many practical situations it is possible to operate the dipole satisfactorily without one, but there may be a slight increased risk of interference if one is not used. Simple baluns can be bought from antenna suppliers, or made.

Does an end fed antenna need to be grounded?

No. It has nothing to do with a “ground” or “counterpoise” any more than a dipole fed at its center. Feeding the end of a resonant length of wire requires generating a high voltage field.

How long is a 15m dipole?

Approximate Lengths for HF Ham Band Dipole Antennas
Band (MHz) Length (Feet) Length (metres)
14.00 (20 metres) 34.3 10.6
18.068 26.6 8.2
21.00 (15 metres) 22.8 7.04

## How many dipole do I need for each band?

One separate dipole for each band needed. However you can build it to suit your own preferences by using the standard formula for a dipole: 468/freq mhz = total length for each band. Use the formula for your desired center frequency.

### Why choose a random length all band dipole antenna?

The random length all band dipole represents some clear advantages in cost and operational flexibility within the limitations of the average Australian suburban block. There for if you can have only one HF antenna the random length all band dipole would be a pretty good choice.

What is a 40m wire dipole used for?

This combined with a 40m wire dipole makes a great portable setup, giving local NVIS and longer distance coverage with the same antenna. The 40m + 160m version along with an 80m dipole gives 3 popular NVIS bands on a common feedpoint, making it easy to change operating frequency as conditions require.

How do I set up a dipole antenna?

The top most dipole must support the entire weight of the antenna. Start with your lowest (in frequency) band of operation as the main (top) support for the entire setup. Cut it per the formula but add a couple of feet on each end for tuning.