Hey guys which kind of filter I must use RC filter or LC?
Really, why?!You will need a Faraday cage to do any meaningful testing on whatever you end up building.
The 1458 opamp inputs work like the diodes in a crystal radio. They detect any RF within the bandwidth of the coil and its capacitance.The '1458 opamp used in your post #17 linked circuit has a unity gain bandwidth of only 1MHz. I don't see how it can possibly operate up to even 50MHz, yet alone 500GHz as claimed.
the op-amp doesn't amplify at signal frequency, it just looks for rectified RF from the diodes.That circuit is useless.
The op-amp gain has declined to (1) one at about 3 MHz and the lowest cell phone frequency is 700 MHz.
The gain resistors set no limit on the op-amp, it has no frequency filters, and the input impedance is so high (1 Terraohm) it would pick up geese flying overhead in the vast open tundra of the arctic circle. It is obvious that it won't shut off.
OK. I exaggerated, but you get the idea.. Without something to tune out the power line frequency and radio stations in a city, this "detector" is going to detect constantly.
Because the world is awash in 0.9-2.4 GHz radiation, you need to isolate the circuit from that background level if you want to characterize it for sensitivity, bandwidth, etc.Really, why?!
An RC would probably have to be a twin-T - but not at cell phone frequencies.Hey guys which kind of filter I must use RC filter or LC?
dimensioned dipole?!!!A correctly dimensioned dipole is probably the most practical approach.
2 bits of wire pointing away from the feed point.dimensioned dipole?!!!
It literally is impossible to say, since you have given no clue as to what "work" means. What is this for, what is the environment in which you are trying to discriminate cell phone carriers from background radiation, what does the output signal have to do, etcetcetcetcHereis 2 newer versions of that detector:
Which one can work?
You will have to build it to find out if it does what YOU need.
As has been pointed out. We still do not know the specifications required to fulfill the task. They remain frustratingly absent from your request.
Designer said it's cell phone detector, no more specifications unfortunately.It literally is impossible to say, since you have given no clue as to what "work" means. What is this for, what is the environment in which you are trying to discriminate cell phone carriers from background radiation, what does the output signal have to do, etcetcetcetc
ak
No it's correct full wave rectifier, I think simulator is crap, other simulators works different!!!Then the connections are wrong or one or more diodes is duff.
I suspected I got that one wrong.the op-amp doesn't amplify at signal frequency, it just looks for rectified RF from the diodes.
by Jake Hertz
by Aaron Carman
by Duane Benson
by Jake Hertz