# Tuning loop antenna tuning help

1. ## how to reduce the inductance of a 3 loop antenna

Hello Guys ,

Please have a look at the following loop(15mm length 2mm thick) antenna for 432Mhz Transmitter hand held device ,which is for PCB. I want to know about the following;

1) What value of Variable capacitor to select (PCB is FR4 , 1.6mm thick standard).

2) Can loop be made small if yes what dimension.

Thank you
-Ts

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2. ## wonder loop antenna

It needs full study before commenting on your questions.
Let say,
1)you need the tuner for a range then what is the frequency range interested?
2) you have variable cap in series, what is the inductance of the circuit?
3) then calculate the C range

finally yes you can reduce the loop dimensions.

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3. ## reducing inductance of loop antenna

Originally Posted by kspalla
It needs full study before commenting on your questions.
Let say,
1)you need the tuner for a range then what is the frequency range interested?
2) you have variable cap in series, what is the inductance of the circuit?
3) then calculate the C range

finally yes you can reduce the loop dimensions.
Thanks ,

Actually I require an antenna for 432Mhz , I place the track as hown around 15cm approx Lambda/4 . The variable cap I see was an example from RFM app note (should the capacitor be placed parallel to loop).

I need suggestion can the loop be left ungrounded when we are furnishing Lambda/4 requirement.

Now when I use FR4 , 1.6mm thick dielectric 4.7 what could be the best bet for tuner capacitor . I am unsure what the inductance might come out at that frequency.

-Ts

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4. ## Tuning loop antenna tuning help

You previously said length is 15 mm, now 15 cm. I also wonder what's the length of a loop? So what's the loop geometry?

P.S.: For some reaosn, the drawing wasn't visible to me. The dimensions are still unclear, but I wouldn't call it a loop, it's rather a meander. A loop is a magnetic antenna, that has an enclosed area as significant parameter. By adding a meander, you increase only the inductance but not the area. A meander may have more effect with a monopole (open end) antenna.

5. ## Re: Tuning loop antenna tuning help

Originally Posted by FvM
You previously said length is 15 mm, now 15 cm. I also wonder what's the length of a loop? So what's the loop geometry?

P.S.: For some reaosn, the drawing wasn't visible to me. The dimensions are still unclear, but I wouldn't call it a loop, it's rather a meander. A loop is a magnetic antenna, that has an enclosed area as significant parameter. By adding a meander, you increase only the inductance but not the area. A meander may have more effect with a monopole (open end) antenna.
Apologies , that was a typo it is 15cm (Lambda/4 @ 432MHz) . I repost the schematic here ;

'A' drawing is a meander and 'B' is I try to tune a meander . Actually the antenna is for a short range link and it has to suffer hand effect and nearby metallic box . I think as the range is not critical 10meter or so , therefore go for this type of design . I am at this point of time unable to download or study HFSS or other simulation but some time in future will definitely download it .
I require suggestions as to what type of antena is the best , the A or B . The B has a quality of a loop as well to stay immune from coupling effects. If one goes for 'B' then what tuner capacitor is required . I couldnt get the Inductance of this type of trace at 432MHz difficult . If trimmer capacitor option is better then please advise value?

Thanks
-Ts

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