Atec Agilent-11691D - Manual (Page 2)

2
Broadband 20 dB
directional couplers
Models 11691D and 11692D high
directivity couplers are precision
instruments designed for broad-
band swept reflectometer applica-
tions in the 2 to 18 GHz
frequency range. With their wide
frequency coverage, one of these
couplers can replace several cou-
plers without performance degra-
dation, thus adding convenience
and economy to swept reflection
and transmission coaxial
microwave measurements by
reducing setup and calibration
time. In addition, the broad fre-
quency coverage of the 11691D
directional coupler makes it ideal
for leveling applications of broad-
band sources. Its high directivity
makes it possible to achieve excel-
lent source matches not achievable
with directional detectors.
Specifications
Simultaneous reflection and
transmission measurement
These couplers are ideal in
reflectometry measurements.
The reflection and transmission
characteristics of a device can be
measured conveniently from 2 to
18 GHz. Figure 1 shows a test con-
figuration in which an 11692D
dual coupler and an 11691D single
coupler are used to separate and
isolate the incident, reflected, and
transmitted signals in a swept-
frequency measurement of reflec-
tion and transmission. These sig-
nals are detected and their ratio
displayed on a CRT. The 11691D
single coupler compensates in the
transmitted signal for the coupling
variations “seen” by the reference
detector. The compensated ratio (Etran/Eref),
being virtually flat, permits high-
resolution transmission measure-
ments. These couplers are ideal
companions for the 8755
frequency response test set, a 0.1
to 18 GHz detection and display
system.
Figure 1. Setup for simultaneous swept measurement of insertion loss (A/R)
and return loss (B/R), using 11691D and 11692D couplers.