MM0474
LESSON 5.
POWER MEASUREMENT TECHNIQUES
AIPD Subcourse Number MM0474................. Power Measurements
Lesson Objective ............................. After studying this lesson you
will know the techniques of power
measurements and the procedures on
how to calibrate power measuring
devices.
Credit Hours ................................. Two
TEXT
1.
INTRODUCTION.
a. The basic concept of power is the same for microwave as for low
frequencies; however, the practical aspect of the two are quite different. For
instance, in most circuits, power can be specified and measured in terms of
voltage across the circuit and the current flowing through the circuit as a
result of such voltage.
In microwave, power measurements are made in the
milliwatt region by the bolometric and thermistor methods. These concepts find
wide application in measurements of attenuation, transmission losses, and
related subjects.
b. In previous lessons, the equipment used for power measurements are
discussed. In this lesson you will learn the techniques and use of the power
measuring equipment for making power measurements and calibration of thermistor
mount.
2.
POWER MEASUREMENTS USING THE MODEL 431C/432A POWER METER.
a. RF power measurements are performed using the setup shown in Figure 1.
The power meter is used with one of five thermistor mounts that collectively
cover the frequency range from 0.5 to 40 GHz. Power levels above 10 mW can be
measured by inserting a suitably calibrated attenuator between the thermistor
mount and power source.
b. Procedure
(1) A typical equipment connection for power measurement using the model
431C/432A is shown in Figure 1.
137
Previous Page
