ETS-Lindgren 7606 Coil Antenna/Shielded Coil - Manual (Page 26)

A BOUT THE S IGNAL S OURCE
The signal source may be a signal generator followed by a power amplifier or
current amplifier. The signal generator may be a manual signal generator, a
tracking generator (part of a spectrum analyzer or EMI meter), or a
computer-controlled signal generator. A 30 W power amplifier with an output
impedance of 0.5 Ω will drive the Model 7605 to about 15 A and produce up to
183 dB(pT) at the end of the built-in 5 cm spacer. When the amplifier is set to the
30 W output level, it produces a current of almost 15 A in the Model 7605, but the
actual amplifier power output is only about 9 W; the 30 W amplifier is needed to
be able to provide enough current from a 0.5 Ω source.
At the lower end of the frequency range, it would be better to use an amplifier
with output impedance lower than 0.5 Ω. For example, if the amplifier had a
source impedance of only 0.125 Ω, the power output capability would need to be
only 9.5 W. However, amplifiers and matching transformers to provide an output
impedance of 0.125 Ω are not readily available in the EMC test equipment
marketplace, but those providing 0.5 Ω are; they are typically found in an
EMC laboratory equipped for MIL-STD-462 testing.
The power amplifier and coupling transformer used for Method CS101 tests may
be used for RS101 tests, but the amplifier does not need as much power for
RS101 tests. Higher impedance amplifiers may be practical at the higher
frequencies where much less current is needed to produce the flux densities
required in the RS101 EMI susceptibility tests.
26 | MIL-STD-462D Method RS101 Testing