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AN OVERVIEW OF
MICROWAVE DESIGN
CONSIDERATIONS FOR
SWEPT SOURCES
ARLEN DETHLEFSEN
NETWORK MEASUREMENTS DIVISION
1400 FOUNTAIN GROVE PARKWAY
SANTA ROSA, CALIFORNIA 95401
Rf ~ Microwave
Measurement
Symposium
and
Exhibition
Flin- HEWLETT
~~ PACKARD
www.HPARCHIVE.com
INTRODUCTION
C' Microwave design and testing is highly dependent upon
the use of microwave swept sources. This paper
describes some of the design considerations necessary
to' achieve superior performance in a microwave Swept
Source used for design and production testing
applications.
Many of these concepts would apply in the general sense
to any electronically tuned microwave source.
AN OVERVIEW OF
MICROWAVE DESIGN
CONSIDERATIONS FOR
SWEPT SOURCES
The performance of a microwave swept source is highly
dependent on three major areas:
1. The block diagram concept.
2. The microwave components used in the source.
3. The control and drive circuitry.
This presentation will focus on the first two of these
areas.
MICROWAVE SWEPT SOURCE
DESIGN CONSIDERATIONS
1. BLOCK DIAGRAM
2. MICROWAVE COMPONENTS
3. CONTROL AND DRIVE CIRCUITRY
O'--- -----J
1
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There are many block diagram concepts that can be
considered for a swept source. We will look at some of
the more
advantages
commonly used concepts and review the
of
diagrams, the performance parameters shown here have to
be kept in mind.
each. When considering the block I;
The designer has to make decisions on the relative
importance of each of these performance perameters in
choosing the appropriate block diagram concept.
The design of the microwave components as well as the
drive an control circuitry would also have considerable PARAMETERS TO CONSIDER
impact on these parameters.
WHEN CHOOSING A BLOCK DIAGRAM
Let's now look at some of the block diagram concepts FOR A SWEPT MICROWAVE SOURCE
and determine how these various configurations would
effect the performance of the source.
1. FREQUENCY COVERAGE
2. OUTPUT POWER
3. FREQUENCY ACCURACY AND DRIFT
4. HARMONIC AND SPURIOUS SIGNALS
5. RESIDUAL FM
6. MODULATION REQUIREMEMENTS
7. RELIBILITY
8. COST
The block diagrams may be placed into these four basic
categories.
Category A and B cover a single band of frequencies
using a fundamental oscillator or an oscillator driving
a single harmonic multiplier. Category C & D are block
diagrams for sources covering frequency ranges which
can not be spanned by a single fundamental oscillator.
BLOCK DIAGRAM CATEGORIES
FOR MICROWAVE SWEPT SOURCES
SINGLE BAND' MULTI/BAND'
~~
FUNDAMENTAL
OSCILLATORS
FREQUENCY
MULTIPLACATION
I B I~
DEFINITIONS: