The dynamic electric conductivity, dielectric permeability and refraction and reflection coefficients of a completely ionized gaseous plasma in a high frequency (HF) external electric field are calculated. These results are obtained within the self-consistent field approach developed earlier for the static conductivity determination. The plasma electron density, N_e, and temperature, T, varied within the following limits: 10¹⁹ ≤ N_e ≤ 10²¹ cm⁻³ and 2 × 10⁴ ≤ T ≤ 10⁶ K, respectively. The external electric field frequency, f, varied in the range 3 GHz≤ f ≤ 0.05ω_p, where ω_p is the circular plasma frequency. Thus, the upper limit for f is either in the microwave or in the far infrared frequency band. The final results are shown in a parameterized form, suitable for laboratory applications.