If a system has a monotonically increasing step response, the magnitude of the system function cannot attentuate too rapidly. This well-known fact is given greater precision in this paper by the establishment of a set of lower bounds on the magnitude function, these results being an improvement over some previously published ones. More precisely, if at some

the value of

is known, thereby determining

through

, then lower bounds on

are determined for

and for

> 1. Stronger results are then established for system functions whose impulse responses are monotonically decreasing. The strengthening of these results resides in the fact that

assumes continuous values with

gt; 1 rather than the discrete integer values of the previous case.