Yes, my drawing wasn't accurate but I meant to couple the antenna just like you said.The circuit you show uses a parallel tuned circuit, in series with the antenna; that would reject the frequency it was tuned to rather than select it.
A parallel tuned circuit should connect between antenna and ground, as in the example I posted.
In reality, the antenna would usually either connect to a tap on the main coil, or a coupling coil with far less turns, around the main coil - eg. as in the antenna & first tuned circuit in the example below.
Connecting to the tuned circuit coil at a tap neared the grounded end improves tuning selectivity, whereas anything external connecting to the top "damps" the resonance, like touching a guitar string near the middle rather than a fixed end.
A normal opamp would only work as an amplifier at fairly low (audio) frequencies; if you are trying to receive radio signals you would need to amplify the signal with either suitable transistors or appropriate RF ICs.
A transformer can change voltage and impedance, but with loss of power, they are never 100% efficient.
I'm not sure what the purpose of that is supposed to be?
What frequency or frequency range are you trying to receive?
The amplitude across the tuned circuit may well be 100x or more greater than at the antenna, but the matching tap to feed the next stage amplification also needs to be well away from the top of the coil, for optimum tuning.
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Thank you very much for your answer and the material provided. You clarified me some doubts, I will study it further before asking other questions.The amplitude across the tuned circuit may well be 100x or more greater than at the antenna, but the matching tap to feed the next stage amplification also needs to be well away from the top of the coil, for optimum tuning.
Simple single tuned circuits like that are not very selective and will likely pick up other signals which are near in frequency. That's why practical radio receivers are generally far more complex, with multiple tuned circuits or band filters of some type.
The Superheterodyne system has been the commonest approach for decades. With that, the wanted signal, after the initial front-end tuned circuit frequency selection, is "mixed" with an oscillator (local oscillator) working at a fixed offset from the tuner frequency.
The mixer outputs are the sum and the difference of the two inputs. The difference is a constant, as the local osc tunes at a fixed offset from the front end.
That constant frequency product means all the rest of the RF amplification and filtering can be done at a fixed frequency, with as many gain and filtering stages as needed, before eventually demodulating it to produce the audio or data etc.
More information here - this is a typical AM (long / medium wave) receiver:
Superheterodyne AM Receiver - Working with Block Diagram and Schematics
In this article, we will learn about the working of a Superheterodyne AM receiver or superhet for short with the help of a block diagram.
Thank you for your answer I will study it further, and eventually come again with other questions
Ok please don't joke at me, my intention was reproduce of a small version of the Vasimir propulsor, so basically I need high power radio waves in order to ionize the gas. Then once I have it is another story. I thought that radio waves or any oscillator circuit could be amplified enough, and this was the first attempt circuit, of course I will further study thanks to your prompts. I am not an a electrical engineer rather aeronautical.
OK, so basically an MHD system using plasma.
