Foreword from the Associate Editor [Historical Corner]

In this issue, we host a paper by Pavel Nikitin on Leon Theremin (1896–1993), a Russian inventor who was in the US for quite a long time (from 1927 to 1938). Theremin discovered that the effects of moving objects on the capacitance of nearby circuits could be used to tune a resonant circuit to different frequencies. He then discovered that the movement of a vibrating membrane could be used to change - through capacitive coupling - the input impedance of a monopole antenna the backscattering from which, if illuminated via a continuous wave, would in turn be modulated.