microvolt receiver with antenna..

Thread Starter

styven

Joined Jun 1, 2016
36
The frequency ratio for such a wide band of frequencies is large, while the capacitance ratio for most variable capacitors in real circuits is much smaller. So if you want a resonant antenna, which provides greater sensitivity, a switching arrangement would be required. But most such antennas only have one turn of wire, centered inside the shielding tube by means of beads of a suitable diameter to slide freely while still holding the wire centered. This is done to reduce the capacitance to the tube, which would reduce the tuning range as well as the sensitivity. For a detailed circuit of such antennas visit the "schematics for free" website, which has all kinds of circuits including a number of amplified loop antennas.
I don't provide a link, you will need to visit the site and use the directory tree to locate the circuit drawing. That does require a bit of focus and a minute or two of clicking, but the site is interesting enough that the search can be fun.
misterBill2, you very polite-)
thxs again, i will try there on sit you said-)
 

MisterBill2

Joined Jan 23, 2018
6,309
misterBill2, you very polite-)
thxs again, i will try there on sit you said-)
I am happy to be able to share my insights with others, and some of the threads are very interesting here. Besides all of that, there is that ever-present reminder to be polite and treat folks well. In this particular thread it will be very interesting to see how the project actually functions, given that my knowledge of ionic chemistry is fairly limited, and that it has been many years since I studied chemistry. So we will all be quite educated by the results of this project.
 

Thread Starter

styven

Joined Jun 1, 2016
36
I am happy to be able to share my insights with others, and some of the threads are very interesting here. Besides all of that, there is that ever-present reminder to be polite and treat folks well. In this particular thread it will be very interesting to see how the project actually functions, given that my knowledge of ionic chemistry is fairly limited, and that it has been many years since I studied chemistry. So we will all be quite educated by the results of this project.
very very good-) i;mhappy too
i like that hobyy to do, and why not ?you never know the surprises.
but good you give me ideas, and will be better if you saw to me with your plan how to start, with one
frequency
which frequency for you is good to make that coil antenna? and i will start to build with my pleasure-) and if eazy for you put here in coated photo..))
 
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The 100 uV/m comment was in regard to the hundreds of volts per meter comment by you in post #27.

In 1992 I was taking field strength measurements like the one below. Units are volts per meter in the VLF band, measured 50 cm from unit under test. It looks like the smaller field was about 250 mv/meter, well below hundreds (those occurred too).
View attachment 153862
My 100's of Volts comment was pertinent to an electrical storm as I said so we are going cross purposes here unless you are saying you were 50cm from an electrical storm strike. ;-)
In any event I was just trying to illustrate that a field mill to pick up such teeny signals through air in this way will have to take into account the immense source impedance inherent with air (without the benefit of ionised gasses as in a storm) and the infinitesimal capacitance of the mill against the low input impedance and relatively high capacitance of the ADC sample and hold. The Wiki article shows a differential buffer amplifier to match the one to the other. Without it I think the results would be erratic at best and random most likely.
If somebody has the time and equipment to do the experimental comparison would be interesting.
 
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