User`s guide

Getting Started with Return Loss A Background to Return Loss Measurement

42 Agilent 81610A/11A/12A/13A/14A Return Loss Module, Fifth Edition

To measure the front panel delta you must measure the power

transmitted through the reference cable, “Measuring the Power

Transmitted Through the Reflection Reference” on page 37, and the

power transmitted through the measurement cable, see “Measuring

the Power Transmitted Through the Measurement Patchcord” on

page 38. The system may be represented by Figure 35:

Figure 35 Generalization of a Return Loss Measurement

The transmitted power, (E), is directly proportional P

src

That is:

The constant a is a multiplier giving the proportion of power that the

light source emits that is measured by the power meter.

The constants a

Ref

and a

Meas

apply to the setups described in

“Measuring the Power Transmitted Through the Reflection

Reference” on page 37 and in “Measuring the Power Transmitted

Through the Measurement Patchcord” on page 38 respectively.

This gives the following two equations:

If we divide equation 11 by equation 12, this gives the following

equation:

The loss variation, ∆L, due to exchanging the reference cable for the

measurement cable is given by:

Power Meter

Agilent 81610A

Reflection Reference

src

(D3=

(12)

( D 3=

(13)

( D 3=

(14)

(

---------------

--------------=

(15)

∆/ 10–

-------------- 10–

(

---------------log=log=

(16)