ETS-Lindgren 7405 E & H Near Field Probe Set - Manual (Page 9)

www.ets-lindgren.com Introduction 9
B ALL P ROBE
The shaft of the model 904
ball probe is constructed of a
length of 50 ohm coax. The coax is
terminated with a 50 ohm resistor
in order to present a conjugate
termination to the 50 ohm line. The
center conductor is extended
beyond the 50 ohm termination
and attached to a 3.6-cm diameter
metal ball, which serves as an
E-field pick up. The absence of a
closed loop prevents current flow,
allowing the ball probe to reject the
H-field.
S TUB P ROBE
The model 905 stub probe is made of a
single piece of 50 ohm, semi-rigid coaxial
cable with 6 mm of the center conductor
exposed at the tip. This short length of
center conductor serves as a monopole
antenna to pick up E-field emanations.
With no loop structure to carry current, the
stub probe rejects the H-field.
Standard Configuration
 H-field probes (3)
 E-field probes (2)
 20 cm extension handle
 Carrying case