MullOverThing

Useful tips for everyday

# How do you calculate 1 4 wave antenna?

## How do you calculate 1 4 wave antenna?

1/4 wave length antenna take 300 and divide by the frequency. So 150 MHz becomes 2 meters, 300 MHz becomes 1 meter, 600 MHz becomes 1/2 meter. Then take the length in meters and multiply by 3.28 to convert to feet (unless you want to remain metric). Take that result and divide by 4 for 1/4 wavelength.

Do 5/8 wave antennas need a ground plane?

The absence of a ground plane or very small ground plane will cause the matching circuit for the 5/8 wave to be a little different due to less capacitance between the vertical element and the ground plane, otherwise there is no “reflection or radiation from a second source” to produce gain in a 5/8 wavelength antenna.

### How does a quarter wave dipole antenna work?

Unfortunately, you can’t just put up a quarter-wave long vertical length of wire and expect it to work properly. The necessity for radials underneath the vertical to act as a ground plane, in effect a sort of ‘mirror’ producing an ‘image’ antenna, Fig. 1, – if you like, the missing half of a half-wave dipole – is well known.

Why do you need radials for quarter wave verticals?

Quarter-wave verticals are slightly more difficult to get right though, one reason being their need for radials. Unfortunately, you can’t just put up a quarter-wave long vertical length of wire and expect it to work properly.

#### Which is the simplest form of vertical antenna?

The quarter wave vertical antenna is the simplest form of vertical antenna. It provides good performance combined with an omnidirectional radiation pattern and simplicity of construction. Vertical antennas include: The quarter wave vertical antenna is used at all frequency bands including LF, MF, HF, VHF and beyond.

Can a HF antenna only use half wave dipoles?

Most HF operators make at least some of their own antennas, even if they are ‘only’ dipoles or quarter-wave verticals. There is little that can go wrong with half-wave dipoles and usually they just need a little ‘pruning’ to size using an antenna analyser or an SWR meter, after which they work well.