Hi! Fortunately, or unfortunately depending on one's view, this project will only be simulated because of the remote learning due to the pandemic. So I need not to worry about permissions because we won't really broadcast in real life. I only need to operate this project on a purely theoretical basis.You wish to broadcast on 500 KHz which is close to the spectrum of commercial AM stations. To be heard 50 km away those stations need a lot of power going to their antenna, and you'll also need substantial power. However if anyone picks up your signal (or overtone splatter due to unintended distortion) then you might get an unexpected "visit from local authorities". (Of course it depends on legal restrictions in the country where you live.)
It's important for you to get informed as to what's permissible and what's not. Consider broadcasting on the shortwave bands. If you broadcast on 500 KHz I would limit my signal strength to a short distance, say to the next room. And for a brief period, say a minute at a time.
I set a link margin of 5dB, so the minimum signal power that the receiver should detect would be -45 dBm. I computed the path loss to be 60.4 dB if 50km is used with 500kHz operating frequency. so the transmit power is -45 dBm + 60.4 dB = 51 dBm.Don't know how you arrived at 51 dBm. R&S field strength and power estimator gives me +66 dBm (4 kW) transmitter power for -50 dBm received power and antennas with dipole gain. These days, class D amplifiers are preferred for high power in medium wave range.
-45+60.4 = 15.4 dBmI set a link margin of 5dB, so the minimum signal power that the receiver should detect would be -45 dBm. I computed the path loss to be 60.4 dB if 50km is used with 500kHz operating frequency. so the transmit power is -45 dBm + 60.4 dB = 51 dBm.
But of course, I am really not sure about my methodology so you would probably be correct and thank you for the correction!I will try to design and simulate a class D amplifier. Very much appreciated!
The word "photon" is related not only to the ligth, but to all the EM wavesAll the transmitters I have seen are dark at night and do not produce photons (in post #5).
-45+60.4 = 15.4 dBm
that is 1.3Vrms onto 50ohm load, corresponding to roughly 4Vpp, that is your specified voltage. If you can use a generator able to directly drive a 50 ohm load you have to do nothing, otherwise you'll need a transistor stage having gain=1 but able to match your impedance with the load.
Since is a simulated link I supposed no antennas gain and no losses due to cables.
--- Updated ---
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?