A.H. Systems Model PAM-0118P Pre-Amplifier
10Log
10
[1000] = 30
dBpT = dB
A/m + 2.0
In this equation, the constant 2.0 is derived as follows. The magnetic flux density, B in Teslas (T), is
related to the magnetic field strength, H in A/m, by the permeability of the medium in Henrys per
meter (H/m). For free space, the permeability is given as...
o
= 4
x 10
-7
H/m
Converting from T to pT and from A/m to
A/m, and deriving the Log, the constant becomes:
240 - 120 + 20Log
10
[4
x 10
-7
] = 2.0
dBpT = dB
V + dBpT/
V + Cable Loss
dB
V/m = dBpT + 49.5 dB
A.H. Systems inc. – May 2014
REV D
11
