Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx> Hi Dr R.One question I have been pondering is the transient response for Terry's antenna. At frequencies below the pole formed by the 20 nf base capacitance and the 100 ohm impedance (50 ohm coax + 50 ohm in series) or about 80KHz, neither end of the scope will be effectively terminated. I've run spice on this and the steady state response seems to be OK. However, there is something going on in the simulation that I dont understand that may be related to the lack of termination on either end that makes me wonder about the transient response. Have you tested for transient response either with the amp or without it and if so, how do they compare??? Also, how did the amp compare with no amp with whatever stimulus you had.
I'm thinking with a high BW unity gain amp at the antenna end of the coax, one can buffer the loading effect the coax has on the capacitor divider. The capacitive divider will be closer to ideal and will only see the high input impedance of the amp. With the amp driving with a 50 ohm source impedance, proper termination will be at the source end and reflections will not linger.
Gerry R.
Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>We tested our "simple contraption" against one of Terry's earlier plane wave antennas and there was no noticable difference. With a small op amp inserted we were even able to measure charge on passing clouds on a non-stormy day. During a storm the op amp was not necessary.Dr. Resonance