How long should radials be for 20 meters?

The length of radials for a 20 meter amateur radio band should ideally be a quarter of the wavelength, which is approximately 5 meters at a frequency of around 14 MHz. This applies to freely suspended radials that do not touch the ground. This length (Lambda/4) ensures optimal adaptation and performance of the antenna. However, in practice radials can also be shorter, for example if they rest on the ground and are no longer resonant due to the damping. However, an antenna tuner is often necessary to adapt the antenna to the radio.