The performance of practical constant-resistance modulators in relation to their use in f.d.m. systems

Ideally modulators with a constant input resistance produce no frequencies across their input terminals other than those impressed by the signal source. They are thus potentially important in simplifying the requirements of filters in multi-channel f.d.m. communication systems, and in the case of double-sideband signals, in eliminating filters since then the modulators can be directly paralleled. This paper discusses experiments to see how far constant-resistance modulators may approach ideal performance in practice; the results are very encouraging.