1EZ26_1E
3-Port Measurements
with
Vector Network Analyzer
ZVR
Application Note 1EZ26_1E
Subject to change
26 July 1996, Olaf Ostwald
Products:
ZVR incl. Option ZVR-B8
ZVRE incl. Option ZVR-B8
ZVRL incl. Option ZVR-B8
1
Function
by means of which PORT1 of the analyzer is
switched to either PORT1 or PORT3 of
3-Port Adapter. Test port PORT2 of the analyzer is directly connected to PORT2 of the
3-Port Adapter and is not switched over.
3-Port Adapter ZVR-B8 is an optional accessory to all Vector Network Analyzers of the ZVR
family, namely ZVRL, ZVRE, and ZVR, and
extends the two test ports PORT1 and PORT2
to a total of three test ports PORT1, PORT2
and PORT3. The option comprises an electronic single-pole double-throw switch (SPDT)
PORT 1
The principal functions and design of the
3-Port Adapter is shown by a diagram on the
cover:
PORT 2
PORT 3
Fig.: Block diagram of 3-Port Adapter
3-Port Adapter is especially suitable for measurements on special 3-ports such as antenna
diplexers. It has a first port to which the generator signal is fed. The signal is taken to the
second port via the diplexer. The receiving and
transmitting antenna is usually connected to the
second port. The signal received by the antenna
is taken to the third port via the diplexer. The
receiver is connected to the third port.
the same test port of the analyzer, i.e. PORT1,
via the SPDT switch of the 3-port adapter.
Seven of the 3 x 3 different S-parameters of a
3-port device under test (DUT) can thus be
measured directly by means of the 3-Port
Adapter and without rewiring the DUT. These
parameters are shown in bold print in the following scattering matrix of a 3-port:
For measurements on such an antenna diplexer
(as a practical example of a 3-port) connect
generator input to PORT1, antenna output/input
to PORT2 and the receiver output to PORT3 of
the 3-Port Adapter. It is now possible to measure the reflections at all the three ports of the
diplexer and to measure the transmissions from
port 1 to port 2 and vice versa as well as the
transmissions from port 3 to port 2 and vice
versa. A direct measurement of the transmissions from port 1 to port 3 or vice versa is not
possible as these two ports are connected to
1EZ26_1E.DOC
(S) =





S11
S12
S13
S21
S22
S23
S31
S32
S33





The two not directly measurable S-parameters
S31 and S13 can be measured by rewiring the
DUT. In many cases in practice, for instance for
antenna diplexers as mentioned above, the
knowledge of these two S-parameters is not
required and thus additional measurements are
not necessary.
2
29 May 1998
2
Applications
All control possibilities for the SPDT switches
are summarized in the following table:
3-Port Adapter is supplied with operating voltages and controlled via the optional rear-panel
connector labelled 3-PORT ADAPTER. A TTL
signal (CHNBIT0) of this connector controls the
SPDT switch. This signal changes its polarity
synchronous to the active display channel (CH1
to CH4) for an uncoupled channels sweep
(not for coupled channels):
• For the two uneven channels, i.e. CH1 and
CH3, the switch is set for PORT1.
• For the two even channels, i.e. CH2 and
CH4, the switch is set for PORT3.
This feature can be used to display several
parameters of a 3-port DUT at the same time.
Up to four S-parameters can be displayed at the
same time in a split or overlay display on the
screen of the network analyzer. If transmission
S21 from PORT1 to PORT2 and the transmission S23 from PORT3 to PORT2 of a 3-port is
to be measured, it is possible to display S21 in
channel CH1 (PORT1 throughconnected) and
S23 in channel CH2 (PORT3 throughconnected). Thus, two different transmission
paths of the 3-port DUT can be measured and
displayed at the same time. The measuring and
switchover speed is sufficiently high so that an
alignment of the DUT is possible without delay.
CH1
CH2
CH3
CH4
CHN
BIT 1
1
1
0
0
CHN
BIT 0
1
0
1
0
SPDT
position
PORT 1 PORT 3 PORT 1 PORT 3
4-port
Sparam
S31
S32
S41
S42
and S13 and S23 and S14 and S24
Table: Active display channel and correspondig
SPDT switch position of 3-Port Adapter
A combination of two 3-Port Adapters, one
controlled via CHNBIT1 the other via CHNBIT0
allows a plurality of further applications, as for
instance even the measurement of a 4-port
DUT. With port 1 and 2 of the 4-port DUT connected to the first 3-Port Adapter and port 3 and
4 to the second one, the reflection coefficients
Sii at all four ports of the 4-port DUT as well as
eight (in total of twelve) transmission
S-parameters Sij, as indicated in the table
above, can be measured without reconnecting
the 4-port DUT.
Further applications are possible by combining
more than one 3-Port Adapter and a network
analyzer. For example, one can use two 3-Port
Adapters and connect the SPDT input port of
the first 3-Port Adapter to PORT1 of the analyzer and the input of the second one to PORT2.
In this way two 2-port DUTs can be simultaneously measured and compared. For this, two
3-Port Adapters are provided and controlled in
parallel via the above mentioned rear-panel
connector by simply using a Y-cable.
All full two port calibration techniques e.g.
TOM can be additionally utilized and are performed as usual. For 3-port applications two
seperate TOM calibrations are recommended.
One with SPDT switch in position PORT 1, for
instance with display channel CH1 active. The
other with SPDT switch in position PORT 3, with
display channel CH2 active. During measurements the matching calibration data sets are
automatically switched over when the active
display channel is changed.
Another possibility is to use not the TTL signal
CHNBIT0 for controlling the SPDT switch but a
different TTL signal, namely CHNBIT1. For that,
only a slight internal modification of the 3-Port
Adapter is necessary. The signal CHNBIT1 is
already available via the above mentioned rearpanel connector and it also changes its polarity
synchronous to the active display channel (CH1
to CH4), with the difference that for the two
lower channels, i.e. CH1 and CH2, the switch is
set for PORT1, and for the two higher channels,
i.e. CH3 and CH4, the switch is set for PORT3.
1EZ26_1E.DOC
Display
channel
Olaf Ostwald, 1ES3
Rohde & Schwarz
26 July 1996
3
29 May 1998
3
[1]
[2]
Further Application Notes
Order designation
H.-G. Krekels: Automatic Calibration of Vector
Network Analyzer ZVR, Appl. Note 1EZ30_1E.
Vector Network Analyzers (test sets included) *
O. Ostwald: 4-Port Measurements with Vector
Network Analyzer ZVR, Appl. Note 1EZ25_1E.
[4]
T. Bednorz: Measurement Uncertainties for
Vector Network Analysis, Appl. Note
1EZ29_1E.
[6]
[7]
[8]
[9]
Ordering Information
O. Ostwald: 3-Port Measurements with Vector
Network Analyzer ZVR, Appl. Note 1EZ26_1E.
[3]
[5]
4
3-channel, unidirectional,
50 Ω, passive
3-channel, bidirectional,
50 Ω, passive
3-channel, bidirectional,
50 Ω, active
4-channel, bidirectional,
50 Ω, passive
4-channel, bidirectional,
50 Ω, active
3-channel, bidirectional,
50 Ω, active
4-channel, bidirectional,
50 Ω, active
P. Kraus: Measurements on FrequencyConverting DUTs using Vector Network Analyzer ZVR, Appl. Note 1EZ32_1E.
J. Ganzert: Accessing Measurement Data and
Controlling the Vector Network Analyzer via
DDE, Appl. Note 1EZ33_1E.
Type
Frequency
range
Order No.
ZVRL
9 kHz to 4 GHz
1043.0009.41
ZVRE
9 kHz to 4 GHz
1043.0009.51
ZVRE
300 kHz to 4 GHz
1043.0009.52
ZVR
9 kHz to 4 GHz
1043.0009.61
ZVR
300 kHz to 4 GHz
1043.0009.62
ZVCE
20 kHz to 8 GHz
1106.9020.50
ZVC
20 kHz to 8 GHz
1106.9020.60
Alternative Test Sets *
75 Ω SWR Bridge for ZVRL (instead of 50 Ω) 1)
75 Ω, passive
J. Ganzert: File Transfer between Analyzers
FSE or ZVR and PC using MS-DOS Interlink,
Appl. Note 1EZ34_1E.
ZVR-A71
9 kHz to 4 GHz
1043.7690.18
75 Ω SWR Bridge Pairs for ZVRE and ZVR (instead of 50 Ω) 1)
75 Ω, passive
75 Ω, active
O. Ostwald: Group and Phase Delay Measurements with Vector Network Analyzer ZVR,
Appl. Note 1EZ35_1E.
ZVR-A75
ZVR-A76
9 kHz to 4 GHz
300 kHz to 4 GHz
1043.7755.28
1043.7755.29
AutoKal
Time Domain
Mixer Measurements 2)
Reference Channel Ports
Power Calibration 3)
3-Port Adapter
Virtual Embedding Networks 4)
4-Port Adapter (2xSPDT)
4-Port Adapter (SP3T)
ZVR-B1
ZVR-B2
ZVR-B4
ZVR-B6
ZVR-B7
ZVR-B8
ZVR-K9
0 to 8 GHz
same as analyzer
same as analyzer
same as analyzer
same as analyzer
0 to 4 GHz
same as analyzer
1044.0625.02
1044.1009.02
1044.1215.02
1044.1415.02
1044.1544.02
1086.0000.02
1106.8830.02
ZVR-B14
ZVR-B14
0 to 4 GHz
0 to 4 GHz
1106.7510.02
1106.7510.03
Controller (German) 5)
Controller (English) 5)
Ethernet BNC for ZVR-B15
Ethernet AUI for ZVR-B15
IEC/IEEE-Bus Interface for
ZVR-B15
ZVR-B15
ZVR-B15
FSE-B16
FSE-B16
FSE-B17
-
1044.0290.02
1044.0290.03
1073.5973.02
1073.5973.03
1066.4017.02
Generator Step Attenuator
PORT 1
Generator Step Attenuator
PORT 2 6)
Receiver Step Attenuator
PORT 1
Receiver Step Attenuator
PORT 2
External Measurements,
7)
50 Ω
ZVR-B21
same as analyzer
1044.0025.11
ZVR-B22
same as analyzer
1044.0025.21
ZVR-B23
same as analyzer
1044.0025.12
ZVR-B24
same as analyzer
1044.0025.22
ZVR-B25
10 Hz to 4 GHz
(ZVR/E/L)
20 kHz to 8 GHz
(ZVC/E)
1044.0460.02
Options
O. Ostwald: Multiport Measurements using
Vector Network Analyzer, Appl. Note
1EZ37_1E.
[10] O. Ostwald: Frequently Asked Questions about
Vector Network Analyzer ZVR, Appl. Note
1EZ38_3E.
[11] A. Gleißner: Internal Data Transfer between
Windows 3.1 / Excel and Vector Network An alyzer ZVR, Appl. Note 1EZ39_1E.
[12] A. Gleißner: Power Calibration of Vector Network Analyzer ZVR, Appl. Note 1EZ41_2E
[13] O. Ostwald: Pulsed Measurements on GSM
Amplifier SMD ICs with Vector Analyzer ZVR,
Appl. Note 1EZ42_1E.
[14] O. Ostwald: Zeitbereichsmessungen mit dem
Netzwerkanalysator ZVR, Appl. Note
1EZ44_1D.
1)
To be ordered together with the analyzer.
Harmonics measurements included.
Power meter and sensor required.
4)
Only for ZVR or ZVC with ZVR-B15.
5)
DOS, Windows 3.11, keyboard and mouse included.
6)
For ZVR or ZVC only.
7)
Step attenuators required.
2)
3)
* Note:
Active test sets, in contrast to passive test sets, comprise internal bias ne tworks, eg to supply DUTs.
1EZ26_1E.DOC
4
29 May 1998
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