HP 8753E manual Measuring Gain and Reverse Isolation Simultaneously, Press *F p#~~~.p~~~~6~~~~’

Measuring Gain and Reverse Isolation Simultaneously

Since an amplifier will have high gain in the forward direction and high isolation in the reverse direction, the gain (E&l) will be much greater than the reverse isolation (SH.). Therefore, the power you apply to the input of the amplifier for the forward measurement (SZl) should be considerably lower than the power you apply to the output for the reverse measurement (S~Z). By applying low power in the forward direction, you’ll prevent the amplifier from being saturated. A higher power in the reverse direction keeps noise from being a factor in the measurement and accounts for any losses caused by attenuators or couplers on the amplifier’s output needed to lower the output power into the analyzer. The following steps demonstrate the features that best accomplish these measurements.

:.	.....:.:.:.:.:.	_
1 . Press @J ‘~~~~~~.~~~~~:~~::.
.;;;..;;.A;.;...:: ......i:::....	::..:.. ;..a	v;>..:.A...~..;;;=;.......;;.........:.

Coupling the channels allows you to have the same frequency range and calibration applied
to channel 1 and channel 2.
,.” .,.:.:.:.:. ?...I i./i	i.....A	:..:::..:
	;; ___ ..	....,
2. press *F p#~~~.p~~~~6~~~~’
..:	.._... :i.i<<<<...:L...i. ;:.~.~.~...~..~.~.~.~.-i.~.~ ~7::: .i:.. ..i . ;..~...~.~.~.~.~...L..~..~.~ .:: -

Uncoupling the port power allows you to apply different power levels at each port. In Figure 2-49, the port 1 power is set to -25 dBm for the gain measurement (S21) and the port 2 power is set to 0 dBm for the reverse isolation measurement (S12).

3. Press (-1 (jj) ~~~~~~~~~;~~~~~~~~~~.			LMenu) @j@jf md set the power level for
	..::::,.:,:....ii/........~.~....i.._._....~...~~.i i..;A%...;;.. . . . . ii	.:.. .i.i.....SW>>.. .......A..ss...;......s..w;;;...
port 1.		..::::::::...:.~.:.:.:.:...:.:..::.,.:.: .,.,,.:..: /.:..‘::I	. . . . .::.. . . . . .....;...;
	. . . . 2.. :2y .“),j .‘) ,‘.A; .”

4. Press (-2) (Meas] ;:f&m$@.;:;~ -~~~~:~~~~~~ (Menu) ~~~~, and set the power level for port 2.

5. Perform an error-correction and connect the amplifier to the network analyzer. Refer to the

“Cptimizing Measurement Results” Chapter for error-correction procedures.
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		. ..../ ..; ; ...;il.~ * _.

6. tiess c~isplay) ~~~~,~~~~~~~~~~ ~~~~~~~~~~.

You can view both measurements simultaneously by using the dual channel display mode. Refer to Figure 2-49. If the port power levels are in different power ranges, one of the displayed measurements will not be continually updated and the annotation tsll will appear on the left side of the display. Refer to “Source Attenuator Switch Protection”section in Chapter 6, “Application and Operation Concepts,” for information on how to override this state.

Making Measurements 248