I soldered one radio circuit for a wave transmission with ~107 MHz frequency and I got good results. I simulated this circuit in LTSpice, too. What I have seen was that the wave got AM modulated and the result of all was that the circuit feeding voltage was modulated properly according to the input, too. My question is about, if the feeding voltage is responsible for the carrier frequency and if it is the reason for reaching long distance during transmission?



  • 2
    \$\begingroup\$ It's hard to understand what you're asking here. \$\endgroup\$
    – Hearth
    Oct 1 at 23:26
  • \$\begingroup\$ I do not care about impedance matching of antenna for now. What I want to know is, if the voltage that powers up the circuit, is a part of this carrier signal.. What I mean is, carrier signal is kind of signal with DC offset and inside the modulated wave... ? \$\endgroup\$
    – lastime
    Oct 1 at 23:32
  • \$\begingroup\$ You have twi voltage sources which doyou consider "feeding"? \$\endgroup\$
    – RussellH
    Oct 1 at 23:57
  • \$\begingroup\$ did you forget to include some words in the title? ... it makes no sense \$\endgroup\$
    – jsotola
    Oct 2 at 0:06
  • \$\begingroup\$ @lastime sorry, that comment of yours still makes no sense. My native language isn't English, it has always helped me to put things in mathematical formulas. So, I would recommend you 1. Describe the signal that your antenna transmits in a mathematical formula and 2. Then say which parameter of that formula has to do with the voltage you mean. \$\endgroup\$ Oct 2 at 0:29

1 Answer 1


It appears that you have wired an RF amplifier for 107 MHz, following a schematic that you've successfully tested on LTSpice.

You have successfully received at a distance, an unmodulated / amplitude modulated 107 MHz carrier fed to the RF amplifier with it's antenna connected.

The RF amplifier is responsible for amplifying the power of the carrier being fed to the antenna for transmission.

Higher the required range greater the required transmitted power and greater the DC power input to the RF amplifier.


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