I am trying to understand how the attached circuit works, for tuning a transmission/receiver antenna (L1) for double frequency (HF, 500 MHz on the left output and 202 MHz LF right), to be used in nuclear magnetic resonance. In particular, I understand that C8/L2 are a freq. trap resonating at HF, while C5 and the transmission line impedance, tuned to HF, will provide a ground path for LF and a high impedance for HF. I also assume the coil has series/parallel tuning for LF/HF.

I would like to ask, how does the circuit work, how is this circuit tuned and how do the tuning networks (C3, C2, C4 and C6, C7) work? How are they calculated? I would like to adapt this design for 20 MHz/600 kHz frequencies, provided an 80 nH L1, can this be done?

Thank you!

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  • \$\begingroup\$ Get hold of a free simulator is my advice. \$\endgroup\$ – Andy aka Mar 29 at 8:40
  • 1
    \$\begingroup\$ be aware of quarter-wave lines having resonances at many frequencies. \$\endgroup\$ – analogsystemsrf Mar 29 at 13:57

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