# Having issues series resistive and reactive impedance matching

• Engineering
mechorigin
Homework Statement:
Having issues with getting the same series resistive and reactive impedance of the coil and cap they did in the figures
Relevant Equations:
reactance equations, angular frequency, and Q
The only thing I could think of was using Q=sqrt(6000/50)-1 = 10.9, which then gets me XL=545 and XC=550, or 96.4nH, and 0.32pF at resonance of 900Mhz. I tried seeing if Zin=Zout equation would bring me close, so I tried Z=545+(50-550)=45, then XL for 38.5nH was 217.7, and XC for 2.4pF was 74. Of course Z=217+(50-74) equals 193. so 45 does not equal 193. but then I realized there was an absorption method for the stray capacitance inherent in the diodes. totaling roughly 0.36pF for 0.18pF each diode. So from here I tried calculating the two capacitance I had as if they were in parallel, giving me around 0.68pF total. With an XL of 220, and XC of 260 I tried Z=220+(50-260)=10. Closer, but not quite. The full research paper I am referencing doing my homework on: https://www.aimspress.com/article/id/274

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I think the antenna is a quarter wave vertical, presumably 50 Ohms, although I cannot see the impedance of the antenna stated. But I notice that the matching network shown, which is an L-match, is configured to produce a step down in impedance to the diodes rather than the required step up.

• mechorigin
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