The transient response of r.f. and i.f. filters to a wave packet

The paper first treats the general case of the transient response of any general passive network to a wave packet, i.e. a suddenly applied sinusoidal wave, and finds the mathematical restrictions that must be placed on the transfer function in order that the output signal may not begin before the application of the input signal. This result is then applied to the cases of tuned-anode coupling and tuned-transformer coupling. There is no restriction of the results to narrow bands. It appears that the well-known rule that the build-up time is inversely proportional to the bandwidth is not true in general. It holds in certain circumstances, where the circuits are comparatively simple, but it does not hold for more complicated circuits where tuning curves are functions of more than one independent parameter.