Comba Telecom White Paper - Quality Control Analysis of Base Station Antennas
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Transcript of Comba Telecom White Paper - Quality Control Analysis of Base Station Antennas
1 © 2015 Comba Telecom. All Rights Reserved
QUALITY CONTROL ANALYSIS OF BASE
STATION ANTENNAS
July 2015
A Comba Telecom White Paper
2 © 2015 Comba Telecom. All Rights Reserved
TABLE OF CONTENTS ABSTRACT AND NOTES ..................................................................................................................... 3
INTRODUCTION ............................................................................................................................... 4
KEY FACTORS INFLUENCING ANTENNA QUALITY .................................................................................... 4
ANTENNA MANUFACTURING QUALITY CONTROL AND ASSURANCE ........................................................... 4
Software Criterions .................................................................................................................................. 5
Design Software ......................................................................................................................... 5
Management Tools .................................................................................................................... 5
Comprehensive Quality Control System for Product Life Cycle Management .......................... 6
Hardware Facilities ................................................................................................................................... 6
Margin and Tolerance Definition and Control ........................................................................... 7
Quality Materials—Advanced Material Testing Equipment and Scientific
Inspection Method ..................................................................................................................... 7
Strict Procedure Quality Control: Multiple Quality Supervision Aspects ................................... 8
Strict Quality Control Procedure: Component Manufacturing Equipment ................................ 8
ASSURANCE OF ANTENNA PERFORMANCE TESTING ................................................................................ 9
Radiation Parameter Testing Field and Requirements (Far-Field and Compact Range) ........................ 10
Radiation Parameter Testing Field and Equipment Requirement (128 Probes Spherical
Near-Field) ............................................................................................................................................ 11
Requirements of Electrical Test Environment and Equipment .............................................................. 11
SUMMARY ................................................................................................................................... 11
ABOUT COMBA TELECOM ............................................................................................................... 12
3 © 2015 Comba Telecom. All Rights Reserved
ABSTRACT AND NOTES
An unsung hero, the base station antenna is at the core of any wireless
network. Often the final link to end-user devices, the antenna performance
can make or break a network regardless of the robustness of the underlying
baseband technology. It is therefore imperative that mobile network
operators have an understanding of the key indicators of antenna quality and
the underlying processes behind ensuring such quality in order to assess their
antenna solution partners.
This article therefore discussed the factors that impact the antenna quality. It
looks into various aspects of antenna quality assurance including design,
production, testing equipment and facilities. It provides thoughtful ideas for
research and analysis of antenna quality control.
This paper was presented by Comba Telecom as “Quality Control Analysis of
Base Station Antenna” at the 7th
International Conference on
Communications and Networking in China 2012 (“Chinacom”).
Original author credits: Bu Binlong, Lin Xuejin, Carol Ye.
4 © 2015 Comba Telecom. All Rights Reserved
INTRODUCTION The base station antenna is one of the most important components in a
mobile communications system, and the antenna quality has direct impact
on the overall performance of the wireless network system. The network
quality cannot be assured unless antenna quality can be effectively
controlled. Therefore in order to implement effective quality control, there is
a need to analyze and discover relevant factors that determine BTS antenna
performance and quality, such as antenna structure, material, process and
assembling levels, etc. and find ways to ensure high quality antenna.
KEY FACTORS INFLUENCING ANTENNA QUALITY The antenna quality is mainly decided by the design and manufacturing
standards. Under the premise of good antenna design methodology, antenna
structure, material, process and assembling determine the stability, reliability
and durability of antenna performance.
In short, high quality antennas must possess the following three conditions:
1. Excellent design methodology and advanced manufacturing
technique.
2. Good consistency of material, assembly and welding.
3. Strict process control of production work flow and quality inspection.
ANTENNA MANUFACTURING QUALITY CONTROL
AND ASSURANCE In order to manufacture good quality antennas, software and hardware
facilities are necessary. The criteria for good quality antennas are measured
by -high production efficiency and one-time pass rate for electrical
parameters:
1. There must be basic infrastructure established for the software and
hardware including design, material inspection, manufacturing
process control, parameters testing, environmental and reliability
testing and verification, etc.
2. Manufacturing Key KPIs:
• One-time pass rate (Electrical parameters): refers to pass rate
without tuning after assembling. It is one of key KPIs that directly
reflects capabilities of design and manufacturing quality control.
• Number of antennas output and one-time pass rate per unit time:
these two parameters can directly reflects production efficiency
and design quality.
5 © 2015 Comba Telecom. All Rights Reserved
SOFTWARE CRITERIA
DESIGN SOFTWARE High-quality antenna design requires highly efficient electromagnetic and
mechanical simulation software supported by superfast and advanced
workstation to support. An accurate electromagnetic simulation software,
intelligent post-processing optimization software and mechanical simulation
software can achieve high efficiency and accurate results and provide
assurance for excellent electrical specs and reliable mechanical structure.
Due to the complexity of the antenna physical models, Maxwell Equations
and mechanical structures, in order to accomplish the calculation, multi-CPU
need to run in parallel and process data simultaneously. In this case, super
power workstations with massive capacity are required.
Figure 1: Design software simulation interface
MANAGEMENT TOOLS It is difficult to ensure quality products effectively just by human resources,
as quality control involves not only people, but also tools, standards, material
and process. Therefore, advanced management tools must be implemented
in order to achieve effective information transfer, problem tracking, and
document and data control and management. Please refer Figure 2 for
details:
Quality Control System Supporting
management tools
Main functions
Design process control
PDM
Management tools that control from product development project launch to release, ensure customer’s requirements can be met in the development stage.
Pilot and small batch production
Material control
SPC and MES
Incoming material inspection and automatic data collection and analysis for manufacturing process control, to find the root cause of quality issue and solutions
Production process control
Post-Sales Quality Tracking QDM
Quality data management platform for the sold products, to collect customers’ feedbacks and provide fast response to problems and issues.
6 © 2015 Comba Telecom. All Rights Reserved
Figure 2: Margin and Tolerance Definition and Control Flow
COMPREHENSIVE QUALITY CONTROL SYSTEM FOR PRODUCT LIFE CYCLE
MANAGEMENT A comprehensive life cycle management system can provide the assurance of
product quality cross over all the stages including design and development
process, pilot and small-batch production, supplier chain management and
incoming material control, production process control, etc. The procedure
and phases will be managed by program, standards, and documentation.
HARDWARE FACILITIES
Theoretical studies and simulation design need to be verified through testing,
the same for production and assembling to ensure the product consistency.
Therefore the precise mechanical and electrical test equipment and facilities,
such as far-field or near-field chamber, network analyzer, PIM tester and
environmental reliability testing facilities are required as shown in Figure 3.
Figure 3: Test Environment and Facilities
To ensure products quality during mass production, you need to pay high
attention to margin and tolerance for design and manufacturing procedures,
7 © 2015 Comba Telecom. All Rights Reserved
excellent material quality control mechanism and strict quality and process
control.
MARGIN AND TOLERANCE DEFINITION AND CONTROL The discretion of materials and production during the massive production is
unavoidable. In order to overcome the uncertainties and errors during the
process, antenna suppliers should give certain margin and tolerance for
production during the product design, to ensure the high one time pass rate
and prevent the quality drop due to tuning and maintenance.
Figure 4: Test Environment and Facilities
The antenna is highly integrated product comprising of electrical and
mechanical performance and manufacturing techniques. Besides drawings,
working instruction, etc., it also requires some technical documents to
provide the instruction and guidelines for suppliers, IQC, manufacturing and
materials inspection.
QUALITY MATERIALS—ADVANCED MATERIAL TESTING EQUIPMENT AND
SCIENTIFIC INSPECTION METHOD Incoming material inspection includes conventional and advanced
inspections. Conventional inspection normally uses conventional tools or
visual inspections. The conventional inspection has some limitation.
Sometimes the advanced testing equipment and facilities need to be used to
check the texture, thickness of the materials,
While for in depth inspection it can ensure products’ reliability and durability
with the use of professional testing equipment to inspect the texture,
process and thickness of the plating, etc. Some of the advanced testing
equipment are shown in Figure 5.
Plating Tester Edge Compression Tester Insertion Force Tester
Figure 5: Incoming Material Inspection Equipment
8 © 2015 Comba Telecom. All Rights Reserved
STRICT PROCEDURE QUALITY CONTROL: MULTIPLE QUALITY SUPERVISION
ASPECTS Manufacture process for antenna quality control should be monitored in
steps. Details are shown as below:
Figure 6: Antenna Quality Control Processes
STRICT QUALITY CONTROL PROCEDURE: COMPONENT MANUFACTURING
EQUIPMENT After tuning or repair, the stability of antenna electrical parameters,
especially 3rd order PIM will decrease a lot. From this aspect, antenna is not
repairable. Besides, it is unpractical to implement 100% inspection to all
components. Hence, excellent process and equipment are required to ensure
high quality and consistency of the key components during mass production.
9 © 2015 Comba Telecom. All Rights Reserved
ASSURANCE OF ANTENNA PERFORMANCE
TESTING Antenna performance is verified through relevant testing, which includes
electrical parameters, radiating parameters and reliability testing. Radiation
parameter testing has very high requirement for the testing facility and
needs to get special attention. . There are three ways to conduct radiation
parameter testing: far-field, compact range and near-field testing.
Theoretically, all three methods can perform correct and accurate testing. In
fact, due to hardware, testing system and budget constraint, each testing
method has the inhabitant errors, therefore limits the accuracy. Figure 7
shows the comparison among different testing system:
Figure 7: Comparison between Different Test Systems
Therefore, no matter which test system you use, it should have
corresponding technical requirements to ensure accuracy. Details are shown
as following.
10 © 2015 Comba Telecom. All Rights Reserved
RADIATION PARAMETER TESTING FIELD AND REQUIREMENTS
(FAR-FIELD AND COMPACT RANGE)
Ordinary Test field Precise Test Field
Technical
Requirements Parameters Parameters
Basic Requirements
Far-field test requirements
L > 2(D1^2 + D2^2)/λ
Remark:D1 stands for the dimension of source
antenna, D2 stands for the dimension of antenna
under test. Allows algorithm compensation for the vertical pattern if
the distance is not adequate.
L > 2(D1^2 + D2^2)/λ
Remark:D1 stands for the dimension of source antenna, D2 stands for
the dimension of antenna under test.
Net dimension of
Compact Range
>25m×12m×12m
Shielding requirements of indoor field
>-60dB >-60dB
Caliber field (quiet zone)
requirements
Dimension of quiet zone
Larger than the dimension of antenna under test.
>3m×3m×3m
Reflection level of the quiet zone
>-41dB >-45dB
Magnetic conicity
<0.5dB <0.3dB
Amplitude fluctuation
<±0.25dB <±0.15dB
Level difference between
horizontal and vertical
polarizations
<0.5dB <0.3dB
Radiating performance
testing requirements
Gain testing error range
<±0.5dB; <±0.3dB;
Test stability of gain
<±0.2dB; <±0.1dB;
Pattern testing error
range
-10dB level:<±0.3dB; -15dB level:<±0.7dB; -25dB level:<±2.0dB; -30dB level:<±2.7dB.
-10dB level:<±0.2dB; -15dB level:<±0.4dB; -25dB level:<±1.2dB; -30dB level:<±1.5dB.
11 © 2015 Comba Telecom. All Rights Reserved
RADIATION PARAMETER TESTING FIELD AND EQUIPMENT
REQUIREMENT (128 PROBES SPHERICAL NEAR-FIELD)
Basic requirements
Technical Requirements Parameters
Shielding requirements >-60dB
Dimension of quiet zone Larger than the dimension of antenna under test.
Reflection level of quiet zone >-40dB
Consistency requirements
of probe performance
Amplitude uniformity <±0.15dB
Phase uniformity <±0.2º
Cross polarization >-35dB
Radiation performance
testing requirements
Gain testing error range <±0.5dB;
Test stability of gain <±0.2dB;
Pattern testing error range
-10dB level: <±0.3dB; -15dB level: <±0.711dB; -25dB level: <±2.0dB; -25dB level: <±2.7dB.
REQUIREMENTS OF ELECTRICAL TEST ENVIRONMENT AND
EQUIPMENT
Items Requirements
Shielding requirements
>-60dB
Stability of field VSWR
Choose the antenna under test with VSWR<1.35, the difference of VSWR measured should be within ±0.05 when the antenna consecutively moves according to Tianzi way in a wavelength range around the antenna.
Stability of field PIM
Choose the antenna under test with PIM<-110dBm, do a test for 0.25 wavelength of each move in a wavelength range around the antenna, the difference of 3
rd PIMs should be within 5dB. The test system
connects with standard value of load and the test result complies with specifications.
SUMMARY To summarize, BTS antenna quality is determined by design methodology,
material selection and manufacture process control and so on. The quality of
the antenna has direct impacts on the overall network performance. In
general, in order to produce the high quality antenna, the product life cycle
management system has to be implemented to ensure the quality and
consistency. Also the corresponding software and hardware system and
various testing facilities need to be put into place.
12 © 2015 Comba Telecom. All Rights Reserved
ABOUT COMBA TELECOM Comba Telecom is a leading supplier of infrastructure and wireless
enhancement solutions to mobile operators and enterprises to enhance and
extend their wireless communications networks. With over 50,000 system
deployments around the world including turnkey in-building systems,
urban/rural wireless systems, and transport wireless networks, Comba
Telecom’s end-to-end network solutions include consultation, network
design, optimization and commissioning.
Comba Telecom’s product portfolio includes DAS, small cells, tower mounted
systems, antennas, subsystems, passive accessories, Wi-Fi systems and digital
microwave links.
Listed on the Hong Kong Stock Exchange, Comba Telecom is headquartered
in Hong Kong and has operations throughout the Americas, Europe, Middle
East, Africa and Asia Pacific. To learn more, visit www.comba-telecom.com
and follow Comba Telecom on LinkedIn for regular updates.
www.comba-telecom.com [email protected]
© 2015 Comba Telecom. All rights reserved. Comba Telecom reserves the right to change, modify, transfer, or otherwise revise this
publication and the product specifications without notice. While Comba Telecom uses commercially reasonable efforts to ensure the
accuracy of the specifications contained in this document, Comba Telecom and its affiliated companies will assume no responsibility for
any errors or omissions. Nothing in this publication forms any part of any contract.