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MIT's demonstration places two 120-turn coils face to face, each with a capacitor. A swept sinusoid drives one circuit; an oscilloscope observes the other circuit's capacitor electric potential difference. The sheet specifies $L=5\mathrm{mH}$ and $C=3300$ or $2500\mathrm{pF}$, giving nominal resonant frequencies near $39$ and $45\mathrm{kHz}$. It presents a procedure, not a measured dataset.^[ref]

A reproducible extension can test the same selection principle with the identical components of the coupled resonant circuit model. Prepare two separate series loops, measure their actual inductances, capacitances and coil electrical resistances, and include generator Thévenin resistance in the driven loop's total $R_1$. Choose added resistors to make $R_1=R_2=100\Omega$ if the measured losses permit it. Include a known $R_s=50\Omega$ sense resistor within $R_2$. Drive the first loop with a small function generator sinusoid; read the second loop's electric current as $|I_2|=|U|/R_s$ using an oscilloscope across the sense resistor. Here $U$ denotes the sense reading, distinct from the source electric potential difference $V$ in the model.

Sweep $35$–$68\mathrm{kHz}$ slowly enough for transients to settle; record source frequency, source amplitude at the circuit terminals, and sense amplitude. Repeat at fixed coil spacing after changing one capacitor, then at fixed components after changing spacing. Turn the drive off to establish the background; rotate the receiving coil toward a right angle to test inductive coupling; restore its orientation and repeat to check drift. These are proposed controls, not observations reported by MIT. Keep probe loading small and account for it if not negligible. A grounded oscilloscope can electrically join the loops if attached to both: use an appropriately isolated differential input for any simultaneous primary measurement, or measure the primary separately.

Recovering deliberately chosen long and short generator bursts on the receiver trace demonstrates symbol timing. The essential inference is narrower than a long-distance radio test: nearby coils primarily exchange energy through mutual inductance in the near and far field regime dominated by the near field. Coil spacing, detuning and background controls distinguish this coupling from a direct wire connection or incidental pickup. They do not by themselves demonstrate reception of propagating radio waves in the radiation zone.

Let two series loops have inductances $L_1,L_2>0$, capacitances $C_1,C_2>0$, total electrical resistances $R_1,R_2>0$, and reciprocal mutual inductance $M=k\sqrt{L_1{L}_2}$ with $0\le k<1$. For a steady sinusoid of angular frequency $\omega >0$, choose complex peak amplitudes with time convention $e^{\mathrm{i}\omega t}$. An ideal source of peak electric potential difference $V$ drives loop 1; loop 2 has no independent source. ThenEliminating $I_1$ proves the response formula. Reversing one coil changes the sign of $M$ and the relative wave phase, but leaves this amplitude response unchanged. The measured sense ratio is $|R_s{I}_2/V|$, with $R_s$ included in $R_2$, not added a second time.

For identical loops at their uncoupled resonant frequency ${\omega }_0=1/\sqrt{LC}$,Writing $x={\omega }_{0}M/R$ makes this $x/[R(1+x^2)]$. Its derivative has the sign of $1-x^2$, so response at this fixed frequency is largest when $x=1$, equivalently $k=1/Q$. Too little coupling transfers little excitation; excessive coupling reduces the response at the original centre frequency. This is a fixed-frequency optimum, not a universal optimum over every possible receiver and drive frequency.

For the chosen values, $k=1/Q=0.063246$ gives $M=0.31623\mathrm{mH}$. At source peak $V=0.100\mathrm{V}$, the secondary peak electric current is $0.500\mathrm{mA}$ and the sense peak electric potential difference is $25.0\mathrm{mV}$. The primary peak electric current is also $0.500\mathrm{mA}$, so source mean power is $25.0\mu \mathrm{W}$: each loop dissipates $12.5\mu \mathrm{W}$, checking conservation of energy. Here $V$ is the equivalent ideal source behind $R_1$; a generator's terminal reading must be converted using its measured Thévenin resistance.

In the lossless identical-loop limit, the normal modes have equal or opposite electric currents, making their effective inductances $L+M$ or $L-M$. ThusAt $k=0.20$ these are $45.944$ and $56.270\mathrm{kHz}$. Finite electrical resistance broadens and shifts the driven peaks, so the exact response formula, rather than these lossless values, generates the plot. Changing a capacitor moves the uncoupled tuning through $f_0\propto C^{-1/2}$: increasing it by $21\%$ lowers $f_0$ by the factor $1/1.1$. The model explains why tuning and coupling must be adjusted together; it supplies no transatlantic propagation or detector-threshold prediction.