Recent content by reakka

Thank you very much for taking the time to analyze the circuit. I still don't quite understand, and maybe I am missing something, but your graphs only confirm what I have said (was this your intention?). I should also clarify a few things: 1. I am not measuring S11, rather (1+S11)/(1-S11) *...

i am bumping this. I am still confused on the matter, and no matter what I have tried in experiment and simulation I am still only getting one resistance peak. I am convinced that C2 does not produce a second peak (it does shift the reactance along the vertical axis). Can anyone else help me...

I completely understand what you are saying. I should expect a dip in the reactance for the series resonance. I will try this out when our equipment is free tomorrow. Thank you

I am using a network analyzer, so I think the output impedance is 50 ohms. I don't think I need to do any of what you are suggesting. I am measuring S11.

Okay. I can't use LTspice because I am on a Macbook. But what I did do was build the circuit, and lo and behold: the series capacitor does NOT affect the resonance peak for parallel resonance and there is NO peak for series resonance. Can somebody tell me what's going on now? -_- It seems my...

I seriously believe you, but what's the balls is going wrong with my simulation. Is LTspice assuming that the inductor has some resistance? If so, what is this resistance (I assumed it to be 1 ohm). Why am I still getting one peak? Oh, and sorry I'm used to saying "real impedance" for the real...

Here is a diagram from Fukushima: http://i.imgur.com/mTkIH.png I observe no series resonance which should be a low real impedance peak, not a dip.

I ran again with 1 hertz resolution. Only peak I see is at 2.3 Mhz, and this is real impedance. Why would there be a dip in real impedance?

We are measuring reactance? In that case, yes I get 2 peaks. But the resonance is determined at the peak of the real impedance. What is the significance of peak reactance? I am not taking any output, I am just measuring the real/imag impedance at discrete 1MHz intervals.

syms w; L = 8000; %nH C1 = 600; %pF Cs C2 = 600; %pF Cp R = 1; %Ohms z_L= 1i*w*L*10^6*10^(-9); z_R = R; z_C1 = 1/(1i*w*10^6*C1*10^(-12)); z_C2 = 1/(1i*w*10^6*C2*10^(-12)); z = 1/(1/(z_L+z_R)+1/z_C1) + z_C2 + 5000; f = (0:20); X = real(subs(z,w,2*pi*f)); Y = imag(subs(z,w,2*pi*f)); figure...

Hmm, I must be doing something wrong. Is my impedance expression (first post) correct? I can email you my code if you don't mind.

Thank you for the reply. I see see no peak for series resonance, I have swept 0-100 Mhz for L = 8 nH, C1 = 600 pF, C2 = anything (doesn't matter). So I'm inclined to think you may be mistaken.

I am simulating a series-parallel tank circuit in MATLAB. This means parallel resonance (inductor and capacitor in parallel) with an added capacitor in series. I would assume the resonance condition is w^2LC = 1 and the impedance is 1/(1/(z_L+z_R)+1/z_C1) + z_C2 with C1 being the parallel...