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(a) Experimental configuration to measure and of the MSA at . The signal generator is incorporated in the VNA. The cold attenuator reduces the power that is rereflected at the output of the MSA. is current bias, produces flux bias. (b) Equivalent circuit model of the low-loss transmission line. represents the static capacitance, circuit represents the fundamental resonance.
Real and imaginary parts of the impedance of the low-loss transmission line model shown in Fig. 1(b) measured at . Solid lines are fit to the measured data converted to impedance (circles).
Real and imaginary parts of for microstrip terminated with varactor diode set at for . Circles are data, lines are predictions of model. The inset shows measured resonant frequency (circles) vs varactor capacitance along with transmission line prediction.
Dependence of MSA parameters on flux bias. (a) Resonance frequency (solid) and static SQUID voltage (dashed), (b) microstrip impedance , (c) resistance , (d) capacitance , and inductance .
Measurements of . (a) Measured real and imaginary parts vs frequency (circles) at ; lines are predictions of equivalent circuit model shown in (b).
Measured gain vs frequency for a nine-turn MSA for three different input coupling capacitors. With the 0.5, 2.2, and coupling capacitors, the microstrip resonator is, respectively, undercoupled, approximately critically coupled, and overcoupled.
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