Abstract
The microwave surface impedance of pure type-I superconductors in a static magnetic field is calculated at frequencies in the range 105ωΔ3. In the theory developed, the effect of the static field is to change the quasiparticle energies by an amount p·v, where p is the Fermi momentum and v is the drift velocity associated with the Meissner current. The results are in general agreement with the high-frequency (ωΔ2) experiments, and show the "anomalous" decrease in both surface resistance and reactance that occurs in the experiments at lower frequencies (0.01ωΔ0.2). Finally, the results lead to a simple quadratic field dependence of the surface reactance in the low-frequency limit (ωΔ<0.01), where the form of the calculation is similar to both the experimental results and the predictions of the Ginzburg-Landau theory.