HP 8753E manual Characterizing a Duplexer, Smith chart by pressing @GZ $#$Z~B&KX, Transmit TX

13.Press (Ghan] again.

Observe that the LED is flashing, indicating that channel 3 is active.

14.Rotate the front panel control knob and notice that marker 2 still moves on all four channel traces.

15.To independently control the channel markers:

**,, .:. .::.

Press (Marker) ‘~~~~~~::::.~~, set ~jQ#$JR&~~- to UNCOUPLED.

... .../ i...i.......;.;;;;............i..i ...........i..i/......ii

Rotate the front panel control knob. Marker 2 moves only on the channel 3 trace. Once made active, a channel can be conhgured independently of the other channels in most

variables except stimulus. For example,; . . . . ..a:. once~channel3 is active, you can change its format to a

;:., ,.:.:...:..

Smith chart by pressing @GZ) ;;;$#$Z~B&KX..

.._...,........................... . . . .T.......

Quick Four-Parameter Display

.;. ,.., .,. .,. ...........

The ~~~.~~~~~~~~~:,; menu gives you a choice of standard channel conmations and

>:;:,I; 1.:. $,>,;> ,,.:.::.,;,.,..:.	:.:....:.:.:.:.::..~:.~~~~~~::~~:.:.:.:.~~:::,~:.;,:.:.,.:.:.:.:.:.:.,.: _;,,,,,,i:.,.,<:...
parameter	assignments.
.,., .;:.. ,		..:: .,.....,.,	..........
		:...

Press ~~~~~ in place of step 6.

For more information about the ~~~~~~~~~~~~~ menu, refer to chapter 6, “Application and Operation Concepts. n

Characterizing a Duplexer

The following example demonstrates how to characterize a 3-port device, in this case a duplexer. This measurement utilizes four-parameter display mode.

A duplexer’s three ports are:

nTransmit (TX)

nReceive (Rx)

nAntenna (Ant)

There are two signal paths through a duplexer: from Tx to Ant, and from Ant to Rx. The two signal paths are offset in frequency from each other and have the antenna (Ant) port in common.

This example displays the transmission (TX-to-Ant and Ant-to-Rx) characteristics of the duplexer in the top half of the display, and the reflection characteristics (Tx and Rx ports) in the bottom half. Therefore, the stimulus is set up so that it is centered midway between the transmit and receive frequencies of the duplexer, and the span is set to cover the combined receive and transmit frequencies.

Other display configurations are possible. For example, the display can be configured so that the transmission and reflection of the TX-Ant path is shown in the top half of the display, and the transmission and reflection of the Ant-Rx path is shown in the bottom half of the display.

Making Meesurements 2-13