ETS-Lindgren 6512 Shielded Loop Antenna - Manual (Page 38)

38 6505 Shielding Effectiveness Test Kit www.ets-lindgren.com
11. Adjust signal amplitude on signal generator to maximum allowed by
amplifier input. Establish a reference level by decreasing the
attenuation level unit the signal can be detected by the screen room
wall between them. Reduce attenuation further until signal is again
seen at the same level as without shielding.
The difference in the two attenuator settings is the shielding
effectiveness. If the signal cannot be seen with a zero setting, then the
shielding effectiveness is greater than the attenuation range, or the
power amplifier does not have enough power.
The shielding effectiveness readings are valid only if the power
amplifier is operating in the linear region. This can be verified by
reducing (or increasing) attenuation and observing the receiver signal
on the analyzer or receiver. If the receiving signal also decreases (or
increases) by the same amount, then the amplifier is operating in the
linear region.
Reference:
 MIL-STD 285
 NSA 65-6