17
This demo shows a return loss measurement on a 300 MHz bandpass fi lter.
You will need a directional bridge such as the Keysight 86205A to perform this
measurement. Before making the measurement, calibrate the test setup using
a calibration standard with a known reflection coefficient.
The calibration standard for refl ection measurements is usually a short circuit
connected at the reference plane (the point at which the DUT is connected).
A short circuit has a refl ection coeffi cient of 1 (0 dB return loss); it refl ects
all incident power and provides a convenient 0 dB reference.
Figure 9. Reflection measurement setup
If possible, use a coupler or bridge with the correct test port connector for
both calibrating and measuring. Any adapter between the test port and DUT
degrades coupler/bridge directivity and system source match. Ideally, you
should use the same adapter for the calibration and the measurement. Be sure
to terminate the second port of a two port device.
Please refer to the following procedures when connecting the DUT to the
instrument:
1. Connect the DUT to the directional bridge as shown in Figure 9 and
terminate
the unconnected port of the DUT.
2. Connect the RF OUT port of the analyzer to the directional bridge.
3. Connect the RF IN port to the coupled port of the directional bridge.
CAUTION:
Excessive signal input may damage the DUT. Do not exceed the maximum power
that the DUT can tolerate.
Section 9
Reflection measurements
Coupled port
or
Short
circuit
DUT
N9340B
HANDHELD SPECTRUM ANALYZER
100
kHz - 3.0
GHz
SYS
MODE
MEAS
TRACE
BW/
SWP
AMPTD
SPAN
FREQ
ENTER
MARKER
ESC/ CLR
1
ABC
2
DEF
3
GHI
4
JKL
5
MNO
6
PQR
7
STU
8
VWX
9
YZ_
0
SAVE
LIMIT
PRESET
