# How low can a vertical dipole be mounted?

An answer to this question suggests that raising a vertical dipole sufficiently can create the effect of a phased array. How about the opposite.

How low can a vertical dipole be mounted?

Can a vertical dipole be mounted with the bottom tip at or nearly at ground level?

Can one partially or fully bury the bottom half of the dipole (in a deep enough vertical hole), instead of using a bunch of ground radials as the counterpose for the top half of the vertical dipole?

Here is an analysis of a vertical, 1/2 wavelength, 2 meter dipole suspended at various heights above ground:

As you can see, as you raise the bottom end of the antenna from near ground level up to about 7 wavelengths, the gain increases. At the same time, the elevation angle of the maximum gain decreases (becomes closer to the horizon). As you continue to raise the height of the antenna, the gain becomes somewhat cyclic but the elevation angle remains low.

If you put the bottom end of the antenna directly in contact with the ground, or buried in the ground, the gain will further decrease and the resonance of the antenna will shift. Ultimately, it would be preferable to have a 1/4 wave monopole with an appropriate number of ground or elevated radials in order to realize the maximum gain of this configuration. See How Does Earth Conductivity Affect the “Takeoff Angle” of a Vertical Monopole? and How Does the Performance of Elevated Radials Differ from That of Buried Radials? for more information regarding the ground wire construction implications of 1/4 wave vertical ground plane antennas near the earth.

• Is the parameter for the right-hand vertical axis of the plot above correctly identified? Also, what are the units of measure for the left and right vertical axes? Jan 31 '18 at 10:45
• @RichardFry Thanks for catching that. I have updated the graphic. Jan 31 '18 at 10:56
• Are these results from simulations, or measurements on an antenna range? If a simulation, what parameters did you use for the earth? Jan 31 '18 at 17:58
• @rclocher3 Simulated with real, average ground. Jan 31 '18 at 18:58
• Is that height from the ground to the bottom of the antenna? Or the feedpoint? Or something else? Jan 31 '18 at 23:32

The voltage is high near the end of any dipole. If you locate the bottom end of a vertical dipole at --and especially below!-- the ground, you are greatly increasing the losses.

There is really no specific distance from the earth to the bottom end of the dipole to the earth, above which is good and below which is bad. It just needs to be up and away from the the earth as far as is practical, unless you like heating the planet rather that having the other station hear you. :-)

• Electromagnetic radiation for point-to-point applications in the VHF spectrum and above makes use of the space wave. In general, the higher the radiation center of those transmit antennas above the earth, the greater their useful coverage areas. Jan 31 '18 at 11:03
• The voltage is high near the end of any dipole ... I am sure you mean The voltage is high near the end of any **half wavelength** dipole Jan 31 '18 at 11:52
• Voltage is high at and near the open end of a radiating conductor of any electrical length, because current there always is at, or near zero.. T Jan 31 '18 at 13:55