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Microwave measurements
and test equipment
Updated November
21, 2012
Welcome to the Microwaves101
virtual laboratory! Here you can review the fundamentals of microwave
testing, learn about some commonly used microwave test equipment
and setups, and discover some troubleshooting techniques gleaned
from years of laboratory experience. Study hard and soon you will
be able to call yourself a lab rat!
We use this page as the index for all microwave measurement subsections.
This page is now sponsored by
our friends over at Tegam. Need a piece of test equipment? Check
them out!
Here's links to our growing list
of test equipment and measurement pages:
Mixer noise figure (new for February 2012!)
Lab
safety
Calculating
characteristic impedance from measured reflection coefficient
Load
pull measurement of power devices
Noise
parameter extraction using source pull
Distortion
measurements
RF probing
Slotted-line
measurements
Impedance
tuners
Frequency
meters (a.k.a. wavemeters)
Spectrum
analyzer measurements
including third order intercept, AM and FM, pulsed RF parameters,
and EMI
Power
meter measurements
including one-dB compression
Network
analyzer measurements
Oscilloscope
measurements
including recovery time, and rise/fall time
Group
delay measurements
including time domain and frequency domain techniques
Curve
tracer measurements:
MESFET example
Voltage regulator example
Schottky diode example
A useful modification to the 370B
curve tracer
How to control oscillations
Historic
test equipment
some cool photos!
Measuring
dielectric constant (awaiting inputs!)
If you spend any time at all
in a microwave lab, please review our discussion of connector
care now!
Fundamentals
of microwave testing
A couple of notes about Agilent
before we begin discussing TE (test equipment)... first, Agilent
is the 800 pound gorilla of microwave test equipment. What microwave
engineer wouldn't want a new 110 GHz analyzer under his/her Christmas
tree? And second, for those of you who just arrived from another
planet, Agilent used to be Hewlett Packard. Hewlett Packard built
all of the antique test equipment that lines the shelves of your
test equipment crib. Guess why it's all there? The equipment was
built to last forever. Some of it will still be there when you retire.
They also standardized the instrument controller interface bus (HP-IB)
so that pieces of gear could talk to one another. Please see our
Microwave Hall of Fame to learn more
about Microwave Superheros Bill
Hewlett and Dave Packard and the company they started in a garage.
There are many forms of microwave
measurements, and here we will break them down into a few broad
categories. Perhaps your company would like to contribute to and/or
sponsor a page on one of these topics!
- Transmission and reflection
parameters (small-signal)
- Large-signal parameters (gain
compression, load-pull, etc)
- Frequency generation and conversion
- Waveform analysis (time and
frequency domains)
- Noise figure and noise parameters
- Signal purity
- Antenna patterns
Some of the TE tools of the microwave
trade include:
- sweep oscillators and synthesizers
- network analyzers (vector
and scalar)
- frequency counters and meters
- noise figure meters and
test sets
- power meters
- spectrum analyzers
- high-speed digitizing oscilloscopes
- detectors
- curve tracers
- impedance tuners
- RF and DC probes
Some commonly-used test setups
that will be described by Microwaves101 (when we get around to it
for crying out loud!) are:
- Network analyzers (scalar
and vector)
- Large-signal test bench
for P1db
- TOI measurements
- Noise figure test setups
- When to use waveguide
- Group delay measurements
in time and frequency domains
- Switching time measurements
- Time domain measurements
- I-V measurements, static
and pulsed
- Load pull and source-pull
measurements
And we will share some troubleshooting
tips with you:
How to know when your amplifier
is oscillating, and what to do about it.
Common test figure problems:
open circuit, short circuit, broken connectors.
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