clear skies!   (created 06-02-1999; modified 04-16-2001)

VLFELFe's antenna

antenna located at D64354 Reinheim/Georgenhausen  -  E 8°48'14'' N 49°50'50"

	plathalter	Fig.1 ACTIVE ELECTRIC FIELD PROBE A VLF/ELF electric field probe is always short compared to the wavelength of the received signals. It did not match the rules for common antennas used at higher frequencies. It could be realized as a capacitor in a differend manner. To receive the vertical polarized E it is necessary to place the receptor plate, disc or sphere etc. as high as possible (>2.5m is pretty good) on a insulated post. The antenna shown in fig.1 is preferable in receiving horizontal polarized E in the vicinity of the earth surface. The cutoff frequency at the low end is given by the rods capacity together with the input network of the preamp. The upper limit for VLF is restricted by the capability of the preamp or specially set to a practical value. (I like to detect the 77kHz DCF for a propper time base too.) Ignoring the distortion by power lines, any movement of the antenna (wind, animals etc.) is a reason for extremly strong pseudo-ULF effects due to the static E (earth-ionosphere - approx. 100V/m). For receiving ULF magnetic loops or ground potential antennas could also be employed.
Fig.2 VERTCAL FIELD PROBE To modify the single pole-antenna for a higher signal in vertical polarisation, a disklike plate could be mounted on the top. A grounded couterplate increase the capacity for low-pass characteristics (if you looking for Schumann-Resonances). The receiver is able to handle both channels separately. First results with an antenna of the plate-type are the discovering of insect signals.

Fig.3

GROUND POTENTIAL ANTENNA

The third type of  VLFELVe's antenna is build as a ground potential probe - a so called HALF-WENNER-POLE-POLE. This ULF-antenna is also published by the  ELFRAD-group. Such type of resistive potential probes are commonly used in geological field and underground explorations. A sketch and more information about it is in progress. First results in receiving VLF with this equipment will follow soon. Unfortunately, the base line at my homeside is only 15m and not aligned to the north-south-direction.

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