The electric antenna (E-Field)
The “E-Field antenna” is a PROBE, a high impedance sensor that detects changes in the electric field between ground and atmosphere. The electric field is the electric component of the electromagnetic wave. As already mentioned above, the electric field of the radio waves emitted by cloud-to-ground lightning discharges is mainly oriented vertically. That is, in the simplest case, the e-field antenna is a vertical wire. Such a wire is directly connected to the input of Pre-Amplifier 14.x (System RED) respective pre-amplifier 17.x (System Blue), which is particularly designed for E-field antennas, see Figure 24.
Figure 24: An example of an E-field antenna
Use the build-in antenna (only System Blue), or a piece of wire, 10cm is fine, 1-2,5mm²).
It should be placed high and far away from electrical installations.
Connect the pre-amplifier to Controller via 75 Ohm coax cable (TV) and F-Plug
The E-field antenna is omnidirectional, and we use only one.
The advantages of an e-field antenna are the following:
- Since it receives signals from all horizontal directions, we need only one antenna instead of two antennas.
- The received signals are very clean and free of any resonances frequencies. However, the resonance frequencies of the ferrite rod antennas are mainly eliminated by the damping resistor at the input of Amplifier 12.
- It is possible to determine the polarity of the lightning discharge, if the lightning discharge was not too far away.
- It is easy to construct for a very low price.
The disadvantages of an e-field antenna are the following:
- It is very sensitive to field electric noises.
- It has to be placed outside or at least on an attic, and thus, conditions for lightning protection have to be respected.