I have built a loop antenna and at 100Mhz(this is where I want to use it) it has an impedance (real part) of only 0.2ohms and since the cable is 50ohms I have to do some impedance matching. I wanted to do it with Pi or L networks but I can't find inductor small enough, so is there any idea how to do this? I would be very grateful for any help. Thanks...
loop antenna impedance match
- Thread starter newman555
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A 1 wavelength loop is around 100ohm impedance, if you use 50ohm coax there will be a 2:1 match but it will work.
prcguy
prcguy
There are a lot of loops out there, usually series gamma matched so it would help if you better describe it preferably with a drawing as an attached image file. I don't know why you would want 50 ohms impedance on the FM broadcast band when the input to such a receiver is dual 75 ohms unbalanced and 300 ohms balanced.
Then considering what you're putting yourself through I don't know why you don't just buy an FM antenna and be done with it.
Then considering what you're putting yourself through I don't know why you don't just buy an FM antenna and be done with it.
this is a part of paper i have to write for my university. I have built circular loop with only one turn (it has to be like this), so I can't change anything. Impedance is approximated using formula, but I'm sure it's very low, and it much smaller than 1 wavelength (diameter=0.2m). So is there a way to solve this problem?
It sounds like your making a magnetic loop from the dimensions. Usually these are fed with a smaller coupling loop and the open ends of the loop are tuned to resonance with a variable capacitor or by a fixed capacitor made from closely spaced plates.
See:
http://www.aa5tb.com/loop.html
and many other articles you can find with a Google search.
prcguy
See:
http://www.aa5tb.com/loop.html
and many other articles you can find with a Google search.
prcguy
Ah, a light shines! Since you're not telling us any more than "a one turn loop", in a word... EZ Nec.
I also used capacitor to tune it to resonate at 100Mhz. So is there a way to match impedance to 50 or 75ohms (it doesn't matter to me which, I intend only to use it to measure field pattern and stuff like that )? Transformer, PI or L networks? Help me out here, I really don't know what works with this problem...Thanks again
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