Problem with impedance matching circuit

Thread Starter

Afabiani

Joined Jul 4, 2020
4
Hi! I have a doubt about the impedance matching circuit for RF energy harvesting. I’m not sure if the impedance matching circuit should match the resistance of the rectifying circuit or the resistance of the load I want to power. Hope I explained myself properly. Thank you!
 

Papabravo

Joined Feb 24, 2006
13,967
Hi! I have a doubt about the impedance matching circuit for RF energy harvesting. I’m not sure if the impedance matching circuit should match the resistance of the rectifying circuit or the resistance of the load I want to power. Hope I explained myself properly. Thank you!
A couple of points:
  1. Impedance is a complex quantity. Matching involves figuring out the complex conjugate of the thing you are trying to match.
  2. Working at such low power levels, it seems that you have bigger fish to fry. The RF domain is only part of the problem.
  3. You have not articulated any goals for this project, How will you know what 'done' looks like?
 
Last edited:

crutschow

Joined Mar 14, 2008
25,132
For maximum power to the load, the load impedance should be the complex conjugate of the source.
The source impedance should always be as low as possible.
 

Apfabiani

Joined Mar 21, 2020
1
A couple of points:
  1. Impedance is a complex quantity. Matching involves figuring out the complex conjugate of the thing you are trying to match.
  2. Working at such low power levels, it seems that you have bigger fish to fry. The RF domain is only part of the problem.
  3. You have not articulated any goals for this project, How will you know what 'done' looks like?
I’m fairly new to this so I’m going to try to explain it in a different way. I’m not sure if i have to match the complex conjugate of the rectifying circuit, the complex conjugate of the load i want to power or the overall complex conjugate of the rectifying circuit plus the load. Please, let me know if I’m not explaining myself properly and what else should i add for my question to make sense (if it doesn’t). Thank you very much
 

Papabravo

Joined Feb 24, 2006
13,967
I’m fairly new to this so I’m going to try to explain it in a different way. I’m not sure if i have to match the complex conjugate of the rectifying circuit, the complex conjugate of the load i want to power or the overall complex conjugate of the rectifying circuit plus the load. Please, let me know if I’m not explaining myself properly and what else should i add for my question to make sense (if it doesn’t). Thank you very much
If you don't know or understand the difference between resistance and reactance then just rush headlong into the abyss. You wouldn't understand the explanation anyway. Energy harvesting is one of those areas where they payoff is too small to be worth the effort. Just as an example do you even know how much power is available to be harvested?
 
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