Firstly, for clarity let’s define Insertion Loss:

Insertion Loss is the ratio of power into a matched load (to mean that the load impedance is the complex conjugate of the Thevenin equivalent source impedance) to the power in the load with the subject network / device inserted.

Let’s calculate the InsertionLoss of a lossless 100pF series capacitor of reactance 100Ω @15.91MHz (\(\frac{1}{2 \pi 100e-12 \cdot 100}=15.91 \text{ MHz}\)).

We can do this by mental arithmetic:

The series circuit from the source generator is 50Ω-j100Ω+50Ω, so the total series impedance is 100Ω-j100Ω, and the current magnitude relative to direct connection to the matched load is \(|\frac{100-\jmath 100}{100}|=1.414\) or 3.01dB, InsertionLoss=3.01dB.

Now \(MismatchLoss=InsertionLoss-Loss\), and since the capacitor is lossless, MismatchLoss=3.01dB.

If you are more comfortable believing a simulator… let’s do it in SimNEC.

Above, the power in the load is -3.01dBW and it would be 0dBW without the capacitor in series, ie a matched generator and load.

The SimNEC model shows that the input power to the capacitor from the generator is -3.01dBW, it would be 0dBW with a matched load, so the MismatchLoss is 3.01dBW. The generator does not supply all the power that it would into a matched load, but all of the power it does supply arrives at the 50Ω load because the capacitor is lossless.

## Conclusions

InsertionLoss does not imply any specific conversion of energy to heat.

Loss (conversion of energy to heat) is a component of InsertionLoss, so whilst InsertionLoss does not inform on the magnitude of Loss, Loss is a component of InsertionLoss and so does set an upper limit, ie \(Loss<InsertionLoss\).