Hello everyone,
Recently I got interested in wireless communication and radio signals. I am still an absolute beginner when it comes to RF signals so in this post I wanted to ask some basic questions to increase my understanding about radio communication a bit.
I already started experimenting a bit and managed to make a AM transmitter with a 555 timer using the harmonics of the created frequency (Schematic below, demonstration:
). Firstly here is what I think to understand about RF transmission:
- The antenna used to transmit a signal must be a multiple of the signals wavelenght (like 1/2, 1/4, 1/8 wavelenght).
- The lower the frequency the longer the range of the signal but worse quality.
- The higher the output power the longer the range.
- The concept of AM and FM.
So for example in my 555 timer AM transmitter I used a LC resonator on the output of the 555 to amplify the created signal a bit (measured 35Vpp from 12V input and a frequency of 116kHz) and tuned my AM radio to ~580kHz and sure enough I was able to hear the transmitted signal. However the signal only had a range of ~1 meter. Some day i'd like to be able to transmit a radio signal over long range. But still some questions remain:
- How does an electrical signal trough wires actually get sent into the the air?
- How do radio transmitters pull more power to increase the transmission lenght?
- Why are all radio signals these days in the MHz or GHz range while they offer shorter range?
- The longer the wavelenght the longer the antenna, is there a minimal lenght for an antenna, like can i use a 1/128 wavelenght antenna for really low frequency? or would it be completely useless?
- What is the difference about all the antenna's out there (dipole monopole loop antenna's etc.) performance wise?
- Do I need to know any other subjects to fully understand radio transmission?
Thanks for helping me out,
Gustav
Recently I got interested in wireless communication and radio signals. I am still an absolute beginner when it comes to RF signals so in this post I wanted to ask some basic questions to increase my understanding about radio communication a bit.
I already started experimenting a bit and managed to make a AM transmitter with a 555 timer using the harmonics of the created frequency (Schematic below, demonstration:
- The antenna used to transmit a signal must be a multiple of the signals wavelenght (like 1/2, 1/4, 1/8 wavelenght).
- The lower the frequency the longer the range of the signal but worse quality.
- The higher the output power the longer the range.
- The concept of AM and FM.
So for example in my 555 timer AM transmitter I used a LC resonator on the output of the 555 to amplify the created signal a bit (measured 35Vpp from 12V input and a frequency of 116kHz) and tuned my AM radio to ~580kHz and sure enough I was able to hear the transmitted signal. However the signal only had a range of ~1 meter. Some day i'd like to be able to transmit a radio signal over long range. But still some questions remain:
- How does an electrical signal trough wires actually get sent into the the air?
- How do radio transmitters pull more power to increase the transmission lenght?
- Why are all radio signals these days in the MHz or GHz range while they offer shorter range?
- The longer the wavelenght the longer the antenna, is there a minimal lenght for an antenna, like can i use a 1/128 wavelenght antenna for really low frequency? or would it be completely useless?
- What is the difference about all the antenna's out there (dipole monopole loop antenna's etc.) performance wise?
- Do I need to know any other subjects to fully understand radio transmission?
Thanks for helping me out,
Gustav
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