LpathdB

LpathdB is a unitless, logarithmic metric used to express the attenuation of a signal along a defined path, measured in decibels. It quantifies the difference between transmitted power and received power and is commonly used in wireless and acoustic engineering to summarize path losses. For a single transmitter–receiver pair, LpathdB can be written as LpathdB = 10 log10(Pt/Pr). In multi-segment paths, the overall loss is often modeled as the sum of segment losses: LpathdB = Σ Li(dB).

LpathdB accounts for several physical processes, including free-space path loss, absorption, shadowing by obstacles, and multipath effects. In computational models, these contributions are added or combined with empirical factors to reflect the environment. Practitioners use LpathdB in link-budget calculations and system simulations to estimate achievable range, data rate, or reliability.

Applications span wireless communications planning, RF system design, underwater acoustics, and room acoustics simulations. It is also used in educational materials to illustrate how distance, frequency, and environment influence signal strength.

Limitations: while useful, LpathdB does not by itself predict performance; it is part of a link budget that also includes noise, interference, and receiver sensitivity. Environmental variability and hardware factors can cause deviations from predicted values.

See also: decibels, path loss, link budget.