Hello Ashish and Welcome to RF Cafe,
Analyzer (NA) can measure the output power in the
range you have - 13-14 dBm. It would not be my first
choice. More information is needed. Are you trying
to measure CW, pulsed or other modulated power?
Is the power peak or average? What accuracy do you
need and is it absolute or relative power?
If simple CW I would use a power meter. It has
high accuracy, easy setup and cost less than a NA.
My next choice would be a spectrum analyzer for
CW and especially or pulsed/modulated power. My
last choice would be a NA due to cost, additional
equipment and setup time. However, if all you have
available is a NA then some of these issues are
The method for measuring RF power using
a NA is to perform an S21 (gain measurement). Some
modern VNA have built in routines to do power measurements
and the method should be explained in the users
manual. The procedure is to involved to explain
in this format. I would go to Agilent or Anritsu
and download their application notes on network
analyzers that detail how to do an S21 measurement.
In addition Agilent has several excellent application
notes on RF power measurement (AN-64, AN-64-1 and
AN-1449-1, -2, -3).