Askeri cihazlarda bağlantı yollu elektromanyetik girişim bastırma çalışması
Electromagnetic noise suppression study with connection path in military devices
Yazar: MUSA ŞAGAR
Danışman: PROF. DR. UĞUR ARİFOĞLU
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / Elektrik-Elektronik Mühendisliği Ana Bilim Dalı / Elektronik Bilim Dalı
Derece: Yüksek Lisans, 2023
Konu: Elektrik ve Elektronik Mühendisliği = Electrical and Electronics Engineering

Özet:
Bu tez çalışmasında, MIL-STD-461 G standartı doğrultusunda askeri cihazlar 
üzerinden elektromanyetik girişim (EMI) ve elektromanyetik uyumluluk (EMC) 
konuları üzerine bir inceleme yapılmıştır. EMI, bir cihazın çalışırken ortamda 
bulunan diğer cihazların çalışmasını etkileyebilecek elektromanyetik sinyallerin 
neden olduğu sorunlardır. EMC ise farklı cihaz veya sistemlerin aynı ortamda
birlikte ve EMI olmadan çalışabilme yeteneklerini ifade eder. Askeri standartta 
emsiyon testleri iletilen emisyon (CE) ve yayılan emisyon (RE) olmak üzere iki 
kısma ayrılmaktadır. Bu tez çalışmasında CE testlerinden CE102 testi incelenmiştir.
CE102, özellikle farklı sistemlerde EMC testi gerekliliklerini özetleyen askeri bir 
standart olan MIL-STD-461'in bir alt bölümüdür. CE102, tipik olarak 10 kHz ila 10 
MHz frekans aralığında, güç hatlarına ve kablolara bağlanan iletilen emisyonların 
değerlendirilmesine odaklanır.
Bu çalışmada askeri standartta belirtilen test bileşenleri ve test düzeneği standarta 
uygun şekilde kurulmuş ve ölçümler alınmıştır. Yapılan çalışmalarda farklı iki askeri 
cihazın yaymış olduğu elektromanyetik gürültülerin, frekans değeri ve gürültünün 
büyüklüğüne bağlı olarak gürültü seviyelerini azaltma yöntemleri incelenmiştir. Bu 
tez çalışmasında, laboratuvar ortamında uygulamayla elde edilen test sonuçları 
paylaşılmış ve sonuçlar hakkında değerlendirmeler yapılmıştır. Gürültü seviyelerine 
uygun müdahalede bulunmak için öncelikle gürültünün hangi türden (Ortak mod 
(OM) veya Fark modu (FM)) yayıldığını tespit etmek gerekmektedir. Gürültünün 
türüne göre farklı EMI filtreler tasarlanıp kullanılabilmektedir. Bu çalışmada gürültü 
seviyesini bastırmak için farklı tip ve boyutlarda kapasitör, bobin, ortak mod bobini,
nüve ve filtreler kullanılmıştır. Bu eklemelerin yanı sıra diğer gürültü bastırma 
yöntemleri (topraklama, Faraday kafesi, kabloların ekranlanması) de uygulanarak iki
farklı askeri proje üzerindeki etkileri paylaşılmıştır. Uygulamada kullanılan iki askeri 
cihazın çalışma mantığı ve çalışma gerilimleri farklıdır. Cihazların çalışma 
gerilimlerinin farklı olması sebebiyle standartta verilen sınır değerlerde esneme
yapılarak ölçümler alınmıştır. CE102 testinin limitleri, cihazın tipine, kullanım 
amacına ve uyulması gereken askeri veya endüstriyel standartlara göre değişmektedir. 
Bu testlerde kullanılan limitler, cihazın yaydığı gürültünün tespit 
edilen sınırlar içinde kalmasını sağlamak amacıyla belirlenir. Bu tez çalışmasında 
farklı limit değerlerine sahip cihazların, ilk ölçümlerdeki sınır seviyesinin üzerindeki 
değerleri, kabul edilen sınır seviyelerine indirilmiştir. Gürültü seviyesini düşürmek 
için yapılan her bir değişikliğin cihazlara olumlu veya olumsuz etkileri ayrı ayrı 
ölçülerek çalışmaya eklenmiştir. Bu çalışmanın hedefi, farklı standartlarda emisyon 
testleri yapacak araştırmacılara yardımcı olmaktır.

Abstract:
Parallel to technological developments, devices and systems that emit 
electromagnetic energy are increasing rapidly, and electromagnetic interference 
(EMI) problems arise. The importance of studies on the solution of these problems 
has been understood. Solving EMI problems is a critical step in improving the 
reliability and performance of devices, protecting communication and meeting legal 
requirements. In this thesis, a research study was conducted on EMI and 
electromagnetic compatibility (EMC) issues over military devices in accordance with 
MIL-STD-461 G standard. EMI is the problems caused by electromagnetic signals 
that can affect the operation of other devices in the environment while a device is 
operating. EMC refers to the ability of different devices or systems to operate 
together in the same environment and without EMI. In military standards, emissions 
tests are divided into two parts, conducted emission (CE) and radiated emission 
(RE). CE testing is a type of EMC test performed on electronic devices to measure 
the level of unwanted electromagnetic interference they generate and emit through 
their power and signal cables. CE102, specifically, is a subsection of MIL-STD-461, 
a military standard that outlines requirements for EMC testing in different systems.
In this thesis study, the CE102 test was examined. CE102 focuses on the assessment 
of conducted emissions that are coupled onto power lines and cables, typically in the 
frequency range of 10 kHz to 10 MHz. This testing ensures that electronic equipment 
does not generate excessive electromagnetic interference that could disrupt the 
operation of other nearby device or systems. The purpose of CE102 testing is to 
ensure that devices meet EMC standards and operate reliably without causing 
interference to other equipment. During a CE test, the device under test (DUT) is 
connected to a test setup that includes power and signal cables. The DUT is subjected 
to various operating conditions while its emissions are measured using specialized 
test equipment. The emissions are typically measured across a range of frequencies, 
with specific limits defined by EMC standards. The test components and test setup 
specified in the military standard were set up in accordance with the standard and 
measurements were taken. 
In the studies, the methods of reducing the noise levels of electromagnetic noise 
emitted by two different military devices, depending on the frequency value and the 
size of the noise, were examined. In this thesis, the test results obtained with the 
application in the laboratory environment were shared and the results were evaluated.
There are different methods to reduce the noise level. These are shielding, grounding, 
filtering, isolation, cabling and wiring, EMC compliant design. In this study, 
different types and sizes of capacitance, coil, common mode choke, core and filters 
are used to reduce the noise level. In addition to these studies, other noise reducing 
methods (such as grounding, Faraday cage, shielding of cables) were applied and 
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their effects on two different military projects were shared. The operating voltages of 
the devices are 28 V DC and 220 V AC. Operating voltages are the most important 
factor to determine the limit values of the devices. Therefore, while selecting the 
limit value, the operating voltage of the device was checked and the limit value was 
selected from the standard. Basic curve limit is selected for 28 V DC. For 220 V, 
basic curve + 9 dB is selected. The pass or fail ciriterion depends on for the DUT 
specified limit. Once the limit value is determined, it is necessary to determine which 
type of noise (Common mode (CM) or Differential mode (DM)) is emitted in order 
to intervene appropriately in the noise levels. CM refers to the situation where 
unwanted noise or interference is present on both signal lines with respect to a 
common reference point, typically ground. In other words, the noise is superimposed 
on both signal lines in the same direction. DM refers to the desired signal that is 
present between two signal lines while the unwanted noise or interference is present 
in the opposite direction on those lines. In other words, it's the difference between the 
signals on the two lines. Different EMI filters can be designed and used according to 
the type of noise. When using filters, ready-made filters can be used or special filters 
can be designed to suit the noise level. EMI filters work by attenuating or blocking 
unwanted electromagnetic signal within a specific frequency range while allowing 
desired signals to pass through. They are commonly used in applications such as 
power supplies, electronic equipment, communication systems, and other devices 
that require reliable operation and compliance with EMC standards. EMI filters can 
be designed for various applications, such as conducted EMI filtering or radiated 
EMI filtering. These filters typically consist of passive components such as 
capacitors, inductors, and resistors arranged in specific configurations to achieve the 
desired level of noise suppression. The design and placement of EMI filters are 
critical in achieving the desired level of electromagnetic compatibility and 
interference suppression for electrical and electronic systems. Proper placement can 
help minimize interference both from within the system (conducted and radiated 
emissions) and from external sources. Different systems have different EMI 
characteristics and filter placement must be tailored to the specific application. This 
is particularly important in sensitive applications where interference could disrupt the 
proper operation of equipment, communications systems, or safety-critical systems. 
A customized approach helps filters address specific interference issues the system 
will encounter.
The operating structure and operating voltage values of the two military devices used 
in this study are different. Since the operating voltages of the devices are different, 
measurements were taken by stretching the limit value given in the standard. The 
limit of the CE102 test is determined according to the type of device, the area of use 
and the military or industrial standards that must be complied with. These standards 
provide guidance on emission limits for different frequency ranges and scenarios, 
ensuring that military components can operate effectively without causing or 
succumbing to electromagnetic interference. It's important to consult the specific 
EMC standards applicable to the country or military organization for accurate 
information on emission limits for military components. The limits used in these tests 
are determined to ensure that the noise emitted by the device stays within certain 
limits. The steps specified in the standard must be taken into account in order to 
measure the noise level accurately, to ensure proper operation of the test apparatus, 
and to intervene appropriately in the noise level. The standard states that an 
attenuator should be used to avoid affecting the measurement receiver. The 20 dB 
attenuator and the pulse limiter is necessary for protecting the EMI receiver, it is also 
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providing a better impedance between the signal output of the LISN and the input of 
the EMI receiver. This amount of attenuation is added back to the noise amplitude in 
the data recorder by the measurement program. The accuracy of the test setup must 
be ensured before measurements are taken. Applies a signal level to the LISN's 
power output that is at least 6 dB below the 10 kHz, 100 kHz, 2 MHz, and 10 MHz 
limit. An oscilloscope is used to calibrate the signal level at 10 kHz and 100 kHz. At 
2 MHz and 10 MHz, a calibrated output level is applied directly from the 50Ω signal 
generator. Normal scan is performed for each frequency with the EMI Receiver and 
verified that the applied level is within ±3 dB. If there is a deviation of more than ± 3 
dB in the measured signal levels, the test is not continued and the error in the system 
must be resolved. When the TAC power supply is cut off and all other auxiliary 
devices are turned on, the measured ambient electromagnetic level must be 6 dB 
below the safety margin of the relevant limit values. If a sinusoidal emission signal is 
considered to be at the full limit value, the ambient level will be 6 dB below the limit 
value and the measured value will be approximately 3 dB above the limit value. In 
this case, it remains within the measurement system tolerance. The margin of safety 
was taken into account when making measurements. Once all the above-mentioned 
conditions are met, appropriate measurements can be taken.
In this thesis, it was mentioned that a test device in accordance with MIL-STD-461 G
should be established. Afterwards, by following the steps specified in the standard, 
bandwidth, scanning time, measurement receiver and detector selection and ensuring 
standard conditions are explained. The sources of noise in the measurements taken 
and the interventions to be made are explained. The results of the devices with 
different limit values above the limit level in the first measurements were reduced to 
the accepted limit levels. Different types and sizes of capacitors, CMC and filters 
were used in the measurements. The positive or negative effects of each change 
made to reduce the noise level were evaluated and added to the study by measuring 
separately. The circuit diagram of the components that yielded the best results was 
given and added to the internal structure of the device. This study aims to help 
researchers that will work on emission tests at different standards.