On Sun, Mar 24, 2024 at 07:25 AM, G4AON wrote:
A portable wideband HF active antenna could be calibrated to give the necessary antenna factor (needed to convert dBm to field strength). I haven¡¯t got around to making/calibrating such an active antenna, but it¡¯s not particularly difficult.
I have used a high impedance "E-Probe" type amplifier with a 1m long whip, fitted to a car roof with a magnetic mount. The intention at the time was to build a cheap drive around VDSL interference measurement system. But with fibre to the home now being rolled out, it doesn't seem to be such a big issue any more. However, EEV vehicle chargers may be the next problem.
I calibrated it using the Equivalent capacity substitution method.
You can either calculate or measure the whip capacitance.
And then use the Equivalent capacity substitution method to obtain the antenna factor.
Regards,
Martin
