Agilent Technologies N1921A Service manual

Operating and Service Guide
P-Series Wideband Power Sensor
N1921A and N1922A
Manufacturing Part Number: N1920-90007
Printed in Malaysia
Fifth Edition, October 10, 2012
© Copyright Agilent Technologies Inc, 2005–2012

ii
Notices
No part of this manual may be reproduced in any form or by any means (including
electronic storage and retrieval or translation into a foreign language) without prior
agreement and written consent from Agilent Technologies, Inc. as governed by
United States and international copyright laws.
Agilent Technologies, Inc.
Bayan Lepas Free Industrial Zone
11900 Penang, Malaysia

iii
General Warranty
The material contained in this document is provided “as is,” and is subject to being
changed, without notice, in future editions. Further, to the maximum extent
permitted by applicable law, Agilent disclaims all warranties, either express or
implied with regard to this manual and any information contained herein, including
but not limited to the implied warranties of merchantability and fitness for a
particular purpose. Agilent shall not be liable for errors or for incidental or
consequential damages in connection with the furnishing, use, or performance of
this document or any information contained herein. Should Agilent and the user
have a separate written agreement with warranty terms covering the material in this
document that conflict with these terms, the warranty terms in the separate
agreement will control.
Certification
Agilent Technologies certifies that this product met its published specifications at
the time of shipment from the factory. Agilent Technologies further certifies that its
calibration measurements are traceable to the United States National Institute of
Standards and Technology, to the extent allowed by the Institute’s calibration
facility, and to the calibration facilities of other International Standards Organization
members.
Safety Symbols
The following symbols on the instrument and in the documentation indicate
precautions which must be taken to maintain safe operation of the instrument.

iv
Safety Notices
This guide uses warnings and cautions to denote hazards
WARNING A warning calls attention to a procedure, practice or the like, which, if not
correctly performed or adhered to, could result in injury or loss of life. Do not
proceed beyond a warning until the indicated conditions are fully understood
and met.
The Instruction Documentation Symbol. The product is marked with
this symbol when it is necessary for the user to refer to the
instructions in the supplied documentation.
ESD
This symbol indicates that a device, or part of a device, may be
susceptible to electrostatic discharges (ESD) which can result in
damage to the product. Observe ESD precautions given on the
product, or its user documentation, when handling equipment
bearing this mark.
ISM GRP.1
CLASS A
This is the symbol of an Industrial Scientific and Medical Group 1
Class A product.
The CE mark shows that the product complies with all relevant
European Legal Directives.
ICES/NMB-001 This ISM device complies with Canadian ICES-001.
Cet appareil ISM est conforme à la norme NMB-001 du Canada.
N10149 The C-Tick mark is a registered trademark of the Australian
Communications Authority. This signifies compliance with the
Australian EMC Framework Regulations under the terms of the
Radio Communications Act of 1992.

v
CAUTION A caution calls attention to a procedure, practice or the like which, if not correctly
performed or adhered to, could result in damage to or the destruction of part or all of
the equipment. Do not proceed beyond a caution until the indicated conditions are
fully understood and met.
General Safety Information
The following general safety precautions must be observed during all phases of
operation, service, and repair of this instrument. Failure to comply with these
precautions or with specific warnings elsewhere in this manual violates safety
standards of design, manufacture, and intended use of the instrument. Agilent
Technologies assumes no liability for the customer’s failure to comply with these
requirements.
WARNING BEFORE CONNECTING THE POWER SENSOR TO OTHER
INSTRUMENTS ensure that all instruments are connected to the protective
(earth) ground. Any interruption of the protective earth grounding will cause a
potential shock hazard that could result in personal injury.
Sound Emission
Herstellerbescheinigung
Diese Information steht im Zusammenhang mit den Anforderungen der
Maschinenlarminformationsverordnung vom 18 Januar 1991.
• Sound Pressure LpA < 70 dB.
• Am Arbeitsplatz.
• Normaler Betrieb.

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• Nach DIN 45635 T. 19 (Typprufung).
Manufacturers Declaration
This statement is provided to comply with the requirements of the German Sound
DIN 45635 T. 19 (Typprufung).
• Sound Pressure LpA < 70 dB.
• At operator position.
• Normal operation.
• According to ISO 7779 (Type Test).

Contents
vii
1 Introduction
What You’ll Find In This Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
General Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Initial Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Power Meter and Sensor Cable Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Interconnections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Recommended Calibration Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Overview of the P-Series Wideband Power Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
The Internal Zero and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Performance Tests and Adjustments
Test Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Voltage Standing Wave Ratio (VSWR) Performance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Sensor Accuracy Performance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
System-Level Rise and Fall Time Performance Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Zero Set Performance Test in System Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3 Theory of Operation
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4 Specifications and Characteristics
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Specification Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Frequency and Dynamic Power Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Damage Level and RF Connector Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Power Sensor Maximum SWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Power Sensor Calibration Uncertainty. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Physical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Declaration of Conformity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5 Service
What You’ll Find In This Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
General Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Connector Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Contents
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Performance Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Agilent Sales and Service Offices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

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1Introduction

2
What You’ll Find In This Chapter
This Chapter introduces you to the P-Series Wideband Power Sensors. It contains
the following sections:
• “General Information” on page 3.
• “Initial Inspection” on page 3.
• “Power Meter and Sensor Cable Requirements” on page 4.
• “Interconnections” on page 4.
• “Calibration” on page 6.
• “Overview of the P-Series Wideband Power Sensors” on page 7.

3
General Information
Welcome to the P-Series Wideband Power Sensors Operating and Service Guide.
This guide contains information about the initial inspection, connection, and
specifications of the P-Series Wideband Power Sensors. You can also find a copy of
this guide on the Documentation CD-ROM supplied with the P-series power meters.
Figure 1-1 P-Series Wideband Power Sensors
To make best use of your sensor refer to the chapter “Using P-Series Power
Sensors” in the P-Series Power Meter User’s Guide.
Initial Inspection
Inspect the shipping container for damage. If the shipping container or packaging
material is damaged, it should be kept until the contents of the shipment have been
checked mechanically and electrically. If there is mechanical damage, notify the
nearest Agilent office. Keep the damaged shipping materials (if any) for inspection
by the carrier and an Agilent representative. See “Agilent Sales and Service Offices”
on page 40.

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Power Meter and Sensor Cable Requirements
The P-Series Wideband Power Sensors are ONLY compatible with the P-Series
Power Meters.
Table 1-1 lists the length of cable option, these have no interconnecting cable
requirements, as the cable is permanently connected (hard-wired) to the P-Series
Wideband power sensor.
Interconnections
Connect the cable to the P-Series power meter’s channel input. Figure 1-2 shows
that you must align the red dot on the sensor’s cable and the meter’s connector.
WARNING BEFORE CONNECTING THE POWER SENSOR TO OTHER
INSTRUMENTS ensure that all instruments are connected to the protective
(earth) ground. Any interruption of the protective earth grounding will cause a
potential shock hazard that could result in personal injury.
Recommended Calibration Interval
Agilent Technologies recommends a one-year calibration cycle for the P-Series
power sensors.
Table 1-1 Cable Length Options
Option Description
N1921A-105
N1922A-105
1.5m (5-ft) cable length
N1921A-106
N1922A-106
3m (10-ft) cable length
N1921A-107
N1922A-107
10m (31-ft) cable length

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Figure 1-2 Connecting a Sensor Cable to a Power Meter
Allow a few seconds for the power meter to read the data contained in the power
sensor’s EEPROM.
NOTE Ensure power sensor cables are attached and removed in an indoor environment.
Torque
Table 1-2 shows the connector type (for connection to DUT) for the power sensor
models. A torque wrench must be used to tighten these connectors. Only use a
wrench set to the correct torque value.
Ensure you line up the red dots on the
sensor cable and power meter’s connector
Table 1-2 Wrench Size and Torque Values
Model Connector Wrench Size Torque Value
N1921A Type-N (male) 3/4-inch open-end 12 in-lb (135 Ncm)
N1922A 2.4 mm (male) 5/16-inch open-end 8 in-lb (90 Ncm)

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Calibration
When calibrating a P-Series Wideband Power Sensor, there is no need to disconnect
it from the power source.
The power meter performs Internal Zero and Calibration routines. The process used
for this Internal Zero and Calibration is explained in “Overview of the P-Series
Wideband Power Sensors” on page 7.
The chapter “Using P-Series Power Sensors” in the P-Series Power Meter User’s
Guide explains in more detail the methods used the perform the zero and calibration
of the power sensor.

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Overview of the P-Series Wideband Power Sensors
The P-Series Wideband Power Sensors has two different models.
• The N1921A has a frequency range of 50 MHz to 18 GHz.
• The N1922A has a frequency range of 50 MHz to 40 GHz.
The Internal Zero and Calibration
The P-Series Wideband Power Sensor’s Internal Zero and Calibration process is
used to combine the power sensor and power meter to make accurate power
measurements.
Referring to Figure1-3, Simplified Sensor Block Diagram, the process for the
Internal Zero and Calibration explains how three objectives in this process are
achieved.
Figure 1-3 Simplified Sensor Block Diagram
1. To account for the environment that the system is working in - the temperature
and the presence of electromagnetic signals.
This is achieved during the Internal Zero process, where the Diode Detectors are
isolated from the active amplifier circuitry. The process allows the zero
measurement to be made, regardless of the RF input signal, thus allowing the
sensor to remain connected to the DUT. The isolation is achieved by a network
of transistor switches in the zero and calibration path switching.
2. To account for the combining of the sensor and meter, as these may never have
been used together as a system.

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This is achieved during the Internal Calibration, the Amplifier Circuitry is
isolated from the Diode Detectors by a network of transistor switches and the
sensor’s voltage reference is routed to the Amplifier Circuitry.
3. To verify traceability to National Standards, hence, verifying your
measurements are going to perform to specification.
To achieve traceable and accurate RF power measurements, each sensor is
individually characterized during its production procedure. To achieve optimal
accuracy, a 3-dimensional correction is generated across power, frequency and
temperature. This uses advanced modeling techniques, and is superior in
accuracy and speed of evaluation to the overlaying of linearity, temperature
corrections and calibration factors.
As a confidence check of the connector integrity, the P-Series Wideband Power
Sensor can be connected to any known good signal source (for example, the
50 MHz, 0 dBm reference) and a comparison made.
The calibration factors are stored in the EEPROM during the manufacturing
process. All the compensation data is downloaded to the P-series power meter at
power-on or when the power sensor is connected.
NOTE Between 50 MHz and 500 MHz, the sensor is sensitive to the RF signal propagating
through onto the Detector Amplifier Circuitry and resulting in distorted power
measurements. To reduce this effect, additional filtering is switched into the
measurement path, which results in a 15 MHz video bandwidth limitation for
signals below 500 MHz.
The P-Series Wideband Power Sensor performs internal zero and calibration
automatically upon AC power up. However, to perform a manual confidence check
with an external reference power source (1 mW, 50 Mhz), a 2.4 mm (f) to
N-type (m) adapter is needed as the P-Series Wideband Power Sensor is fitted with
a 2.4 mm (m) connector. This adapter is not shipped together with the P-Series
Wideband Power Sensor.

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NOTE The 2.4 mm (f) to N-type (m) adapter is intended for use only on the 1 mW,
50 MHz power reference of the power meter. Its function as a calibration reference
may be compromised if used for other purposes.
Table 1-3 Adapter
Part number Description Item
08487-60001 Adapter 50 MHz, 2.4 mm

10

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2 Performance Tests and Adjustments

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Test Equipment
The following equipment are required for the performance tests:
Instrument Critical specification Recommended Agilent model
number/part number
Signal generator
(Rise/fall time)
Power range: –50 dBm to +22 dBm at 1 GHz
Output resistance = 50 Ω
N5182A/E8257D/E8267D
Signal Generator
(Zero set)
Power range: –50 dBm to +20 dBm at 1 GHz
Output resistance = 50 Ω
E4438C/E8257D/E8267D
Oscilloscope Analog Bandwidth: 1 GHz and above Infiniium MSO 9104A
Network analyzer Frequency Range: 10 MHz to 40 GHz or
above 94 dB of dynamic range
<0.006 dB trace noise
E8361A/E8361C/E8363B/
E8363C
Calibration kit Frequency Range: DC to 18 GHz or above 85054A/85054D/85056A/
85056D
Diode detector
(Negative)
SMB connector 33334EZ
Power splitter Two- Resistor type Power Splitter, N-type (f)
Max Frequency: 18 GHz
11667A
Power meter Dual Channel Peak Power Meter
Compatible with P Series and N8480 Series
Power Sensor
Absolute Accuracy: ±0.8%
N1912A
Power sensor Frequency: 50 MHz or above
Power range: –30 dBm to +20 dBm
SWR: ≤1.15 at 50 MHz
N8481A/N8487A
Wideband power sensor Power range: –30 dBm to +20 dBm
SWR: ≤1.20 at 1 GHz
N1921A/N1922A
Cable adapter 11730A sensor cable adapter N1911A-200