A25-A28 Receiver Couplers; A29-A32 Test Port Couplers - Keysight N5221A Service Manual

Theory of Operation PNA Series Microwave Network Analyzers
Signal Separation Group Operation N5221A/22A
Normal Measurement Configuration
For those analyzers equipped with configurable test set and source attenuators, with the inclusion of an
external amplifier and accessories, you can calibrate the analyzer and test devices at power levels up to
+30 dBm. You can make measurements in the forward, reverse, or both directions and still achieve these
high power levels.
High Dynamic Range Measurement Configuration
With a few jumper changes, you can configure the measurement configuration for higher dynamic range
measurements. By swapping the front panel jumpers for one port, signal flow through the corresponding
coupler is reversed, increasing the test signal sensitivity by 15 dB.
In the forward direction, for example, the signal flow through the test port 2 coupler (A32) is reversed by
arranging the front panel jumpers such that RCVR B IN connects to CPLR THRU and CPLR ARM connects to
SOURCE OUT.
While increasing forward (S ) dynamic range, the reverse (S ) dynamic range is degraded by the same
21 12
amount.
A25–A28 Receiver Couplers
The source incident signals from the A5 and A8 26.5 GHz sources are sent to the A25–A28 receiver couplers
where a portion of each signal is coupled off to provide the R1, R2, R3, and R4 receiver reference signals for
4-port models or R1 and R2 reference signals for 2-port models.
These reference signals are routed through front-panel jumpers to the A23 and A24 mixer bricks. Refer to
"A23 and A24 Mixer Bricks" on page 5-20 for additional information.
The test signals each go through the through-line arm of a receiver coupler, then through a front panel
jumper to the A29–A32 test port couplers.
A29–A32 Test Port Couplers
The test port signals go into the through-line arm of the couplers, and from there to the test ports and the
DUT.
The coupled arm of the couplers carries the signal reflected from or transmitted through the DUT, to the
receiver for measurement (through front panel jumpers), as inputs A, B, C, and D for 4-port models or inputs
A and B for 2-port models. The coupling coefficient of the directional couplers is nominally 15 dB over the
full frequency range.
5-16 Service Guide N5222-90001