Improvement in low frequency emission test method by live impedance measurement

Imp o emen in Low F equency Emission Tes Me hod by Li e Impedance Measu emen Soydan Çakı Elec omagne ic Labo a o y TUBITAK UME Kocaeli, Tü kiye 0000-0001-8210-2171 Osman Şen Elec omagne ic Labo a o y TUBITAK UME Kocaeli, Tü kiye 0000-0002-5716-3316 Se da Büyük Elec omagne ic Labo a o y TUBITAK UME Kocaeli, Tü kiye 0000-0002-8773-3519 Ma co A. Azpú ua EMC Elec omagne ic BCN S.L. EMC Ba celona Ba celona, Spain 0000-0001-8078-5116 Engin Özdemi Facul y o Technology Kocaeli Uni e si y (KOU) Kocaeli, Tü kiye 0000-0003-0882-332X Abs ac — The MIL-STD-461 CE101 es is one o he essen ial low equency emission es s in he ange o 30 Hz – 10 kHz o mili a y and ae ospace equipmen , howe e , i s applica ion emains challenging. The p ima y conce n is he e ec o he powe sou ce o g id impedance on es esul s because he LISNs a e no unc ional in such a low equency ange. The e o e, he emission le els depend on he sou ce impedance and, consequen ly, he ep oducibili y o es esul s is gene ally poo . In his pape , we ho oughly analyse his p oblem and p opose a solu ion based on he li e impedance measu emen o he CE101 es ci cui . Fo he li e impedance measu emen , we used he CS101 mili a y low equency immuni y es sys em along wi h he addi ion o FFT and cu en measu emen capabili ies. Keywo ds—ae ospace, CE101, EMC, emission, low equency, mili a y, li e impedance measu emen I. INTRODUCTION The CE101 es de ined in he s anda d MIL-STD461G [1] is applied o mili a y and ae ospace equipmen . This es is pe o med o measu e low equency emissions om supply po s o he Equipmen Unde Tes (EUT) in he 30 Hz - 10 kHz ange. Fi s , he CE101 es equi es a calib a ion p ocess pe o med on a known esis i e load o e i y he es bench. Du ing his calib a ion, a simple ci cui shown in Fig. 1 (a) is se o p oduce a known cu en h ough he e e ence esis o a he equencies s a ed by he s anda d. The ea e , he known cu en on he ci cui is measu ed by he CE101 es sys em and i is checked whe he he sys em yields he expec ed esul s. I he de ia ion be ween he known and measu ed cu en is g ea e han ± 3 dB, he sys em is ou o ole ance and canno be used. In he es s age, cu en emissions om he EUT a e measu ed wi h a cu en p obe and a equency-selec i e ecei e , as shown in Fig. 1 (b). Al hough he EUT is supplied h ough LISNs du ing he es , LISNs a e ine ec i e in he low equency ange. The e o e, es esul s become sou ce impedance dependen , which has implica ions in he measu emen 's ep oducibili y and epea abili y. In he scope o his pape , he sou ce impedance is comp ised o he combina ion o LISNs, he line il e s o he chambe and g id/powe sou ce impedance alues. A s udy ha in es iga es he in luence o he sou ce impedance on CE101 es esul s was pe o med in [2]. I was obse ed ha sou ce impedance was modi ied by using di e en ypes o LISNs and chambe line il e s. The esul an disc epancies in he es esul s we e ho oughly demons a ed. A simila issue and i s ele an solu ion we e in es iga ed in he uppe equency ange (150 kHz - 30 MHz) h ough impedance measu emen s ia a Vec o Ne wo k Analyse (VNA) in [3-4]. Howe e , o he bes o ou knowledge, he e is no epo ed wo k o o e come he a o emen ioned p oblem in he equency ange om 30 Hz o 10 kHz. (a) (b) Fig. 1. CE101, (a) calib a ion se up, (b) es se up. In his pape , o analyse he CE101 es and alle ia e he unce ain y and he disc epancies a ising om he es ci cui impedance, we i s ly measu ed he li e loop impedance o he CE101 es ci cui , which includes he EUT, LISNs, chambe il e s, powe supply and cables, in di e en sou ce condi ions. Fo he li e impedance measu emen , we u ilised ou CS101 es sys em whose calib a ion and es se ups a e depic ed in Fig. 2. The CS101 es is a low equency immuni y es which is conside ed he coun e pa o he CE101. Du ing he CS101 es low equency sinusoidal ol age ipples a e injec ed o powe po s o he EUT in he ange om 30 Hz o 150 kHz, as in es iga ed in de ail in [5- 10]. He e, we imp o ed ou CS101 es sys em wi h a complemen a y cu en measu emen ea u e in addi ion o he in insic ol age measu emen . As a esul , he CS101 es sys em was adap ed o impedance measu emen s. In addi ion, we in eg a ed a pos -p ocessing Fas Fou ie T ans o m (FFT) - based ime domain solu ion o sepa a e injec ed ipples om he AC powe equency o he EUT and o acili a e accu a e li e impedance measu emen s unde ad e se g id o EUT supply ol age condi ions. The in eg a ion o he FFT analysis in o CS101 es ing and he de ails o FFT analysis can be ound in de ail in [9-13]. Al e na i ely, in eg a ed FFT ea u es o oscilloscopes can be used ins ead o he pos -p ocessing o expedi ing he p ocess i i is a ailable on he oscilloscope and a p ope FFT- ac i a ed ins umen d i e exis s on he used CS101 es so wa e. Ano he op ion o li e impedance measu emen s o low-cu en de ices may be he VNA me hod employed in [3- 4]. S ill, he CS101-based me hod p oposes mo e obus measu emen s in he low equency ange o high cu en o high ol age de ices. In his ega d, we mus conside ha he VNA is a sensi i e and expensi e ins umen which gene ally s a s e icien ly ope a ing om 10 kHz, consequen ly i is no op imal o he in ended applica ion. (a) (b) Fig. 2. CS101, (a) calib a ion se up, (b) es se up. Finally, we calcula ed he es ci cui loop impedance de ia ions, by using he se up and equa ion gi en in Fig. 4 and in (5) espec i ely, conside ed as co ec ion ac o s be ween di e en low equency es en i onmen s and compa ed hem wi h loop cu en de ia ions o e i y he p oposed me hod. II. METHOD As any EUT can be modelled as a combina ion o a cons an ol age sou ce and an in e nal impedance (The enin equi alen ), we used his model o analyse he CE101 es and alle ia e he unce ain y a ising om he es ci cui impedance. As common mode (CM) cu en s a e no expec ed in his low equency ange, we limi ed he analysis only o he di e en ial mode (DM), and he ele an ci cui diag am is gi en in Fig. 3 o he di e en ial mode. Fig. 3. DM ci cui model o low equency conduc ed emission. In his con ex , The CE101 es sys em, along wi h he li e impedance measu emen se up u ilising he FFT-enabled CS101 es sys em, is depic ed in Fig. 4. The i s channel o he oscilloscope wi h 1 MΩ inpu impedance is dedica ed o ol age measu emen s whe eas he second channel o he oscilloscope wi h 50 Ω inpu impedance is assigned o cu en measu emen s. Fo cu en measu emen s, we used he 50 Ω inpu o he oscilloscope because he cu en p obe ac o s a e gene ally calib a ed o be used along wi h 50 Ω ma ched ins umen s, such as a measu ing ecei e . Al e na i ely, cu en measu emen s may be accomplished wi h a sepa a e equency-selec i e ins umen . In his measu emen sys em, he o al loop impedance o he CE101 es ci cui , which in ol es he EUT, sou ce and cable impedance alues oge he (see Fig. 4), is a ge ed ins ead o sepa a e EUT o sou ce impedance alues. The loop impedance is de ec ed by he a io o he ol age measu ed ac oss he coupling ans o me o he measu ed loop cu en as p esen ed in (5) o be used in he calcula ion o he co ec ion ac o (K) as gi en in (1), which is expec ed o es ablish a link be ween di e en es en i onmen s. He e, ZCE101_ e e ence_loop is he impedance o he es ci cui selec ed as e e ence, and ZCE101_ es _loop is he loop impedance measu ed in he a ge ed CE101 es se up unde in es iga ion. ZCE101_ e e ence_loop and ZCE101_ es _loop include he impedance o he EUT, powe sou ce, and o he componen s, e.g., LISNs, il e s, and cables. The co ec ion ac o is also known as impedance de ia ion. 𝐾 = 𝑍𝐶𝐸101_𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒_𝑙𝑜𝑜𝑝 𝑍𝐶𝐸101_𝑡𝑒𝑠𝑡_𝑙𝑜𝑜𝑝 (1) Then, he emission le el (ICE101_ e e ence_loop) in he e e ence ci cui can be linked o he emission le el (ICE101_ es _loop) in he a ge ed ci cui by using he measu ed impedance de ia ion as gi en by (2), 𝐼𝐶𝐸101_𝑡𝑒𝑠𝑡_𝑙𝑜𝑜𝑝 = 𝐼𝐶𝐸101_𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒_𝑙𝑜𝑜𝑝 × 𝐾 (2) Al e na i ely, emission esul s ob ained in di e en es en i onmen s may be scaled o a p ede ined load such as 50 Ω by using he measu ed loop impedance alues as gi en in (3) and (4). This can be con enien o ha monize emission esul s ob ained om di e en es en i onmen s and make hem compa able be ween each o he . 𝐼𝑠𝑐𝑎𝑙𝑒𝑑_𝑐𝑢𝑟𝑟𝑒𝑛𝑡 = 𝐼𝐶𝐸101_𝑡𝑒𝑠𝑡_𝑙𝑜𝑜𝑝 × 𝑆 (3) In his case, he scaling ac o 𝑆 can be de ined as ollows; 𝑆 = 𝑍𝐶𝐸101_𝑡𝑒𝑠𝑡_𝑙𝑜𝑜𝑝 50 Ω (4) Fig. 4. CE 101 es sys em along wi h FFT and cu en measu emen enabled CS101 sys em used o impedance measu emen . 𝑍𝑙𝑜𝑜𝑝 =𝑉 𝐼 (5) The cu en p obe in he se up shown in Fig. 4 has wo unc ions. One o hem is o de ec he cu en equi ed o he li e impedance measu emen and he o he is o pe o m cu en measu emen s equi ed o CE101 es ing. A e he loop impedance measu emen , he coupling ans o me is emo ed om he ci cui o CE101 es ing. This is made because he measu ed loop impedance only includes he CE101 es ci cui no he coupling ans o me . The emo al o he coupling ans o me is simply a ained by sho ci cui ing he ou pu o he coupling ans o me jus be o e he CE101 es a e he loop impedance measu emen . A e he loop impedance measu emen , he succeeding s ep is calcula ing co ec ion ac o s. The e i ica ion o co ec ion ac o s is pe o med by means o measu ing loop cu en s, conside ed as CE101 emission esul s, in he same es en i onmen and compa ing loop cu en de ia ions wi h impedance de ia ions. The good consis ency be ween he loop impedance and cu en de ia ions is expec ed o e i y he p oposed me hod. We also de eloped a piece o so wa e by using LabWindows/CVI in o de o pe o m impedance measu emen s based on he CS101 es sys em and ca y ou FFT-based ime domain p ocessing o measu e ol age and cu en alues unde he ad e se AC EUT powe equency. The same so wa e is also able o pe o m CE101 es ing a e he impedance measu emen . III. EXPERIMENTAL STUDY Ini ially, we e i ied he impedance measu emen me hod by using lumped elemen s wi h known impedance as es subjec s, speci ically, 0.5 Ω, 50 Ω, 80 µF, 430 µH. Nex , we employed h ee ypes o EUT o e i y ha he p oposed CE101 measu emen me hod imp o ed wi h he impedance measu emen . One o hem was a signal gene a o RF ou pu o e i y he me hod in nea ly ideal condi ions. Fo he simula ion o sou ce impedance di e si y, we employed an asso men o impedance alues (50 Ω, 80 µF, 430 µH) behind he LISNs, and hey we e di ec ly connec ed o he powe sou ce side o he LISNs (see Fig. 5). The o he EUT was a homemade ha monic e e ence de ice which is designed as a squa e wa e gene a o . As he ha monic e e ence de ice was a s andalone de ice and i does no equi e di ec supply ol age coming om LISNs o ope a e, a a ie y o esis o s (50 Ω as he e e ence, 26.6 Ω, 13.3 Ω and 6.6 Ω) we e di ec ly connec ed o he ou pu o he de ice as seen in Fig. 6 o c ea e di e en dummy sou ce impedance alues wi h espec o 50 Ω. A e hese p elimina y measu emen s wi h he p edic able de ices, inally, an uncon olled de ice, an Unin e up ible Powe Supply (UPS) as he EUT, was es ed in an ac ual MIL-STD461 CE101 es se up (see Fig. 7). Ne e heless, we did no ollow he me al-su ace able and 2 m laid cable equi emen s o he s anda d in his se up as hese ules a e no ele an in his equency ange. A clean powe supply (Scha ne , NSG 1007-45) p o iding he EUT wi h 220 VAC, 50 Hz, oge he wi h a a ie y o combina ions o wo in-house chambe il e s [6] and a comme cial chambe il e (ETS, Model: N5007), is used behind he LISNs a he powe sou ce side o supply he UPS and c ea e di e en sou ce impedance si ua ions. Di e en sou ce si ua ions we e c ea ed h ough he inclusion and emo al o he chambe il e s. As he chambe il e s be ween he LISNs and he powe supply we e likely o in luence he sou ce impedance, hey we e e y ins umen al in changing he sou ce impedance. The UPS was es ed on 6 di e en scena ios in agg ega e as gi en and depic ed in Table I. As he UPS was p edominan ly emi ing only in he ange o 30 Hz - 2 kHz, i s es and analysis we e s opped a 2 kHz, and we did no p oceed beyond 2 kHz whe eas he signal gene a o RF ou pu and ha monic e e ence de ice we e es ed and analysed in he en i e CE101 equency ange (30 Hz – 10 kHz). In addi ion, o scena io 5 and scena io 6, which include mul iple chambe il e s, we had o con ine he equency ange o a ound 1 kHz because he ha monics s a o become e y low and unusable beyond 1 kHz o analysis and calcula ion due o he inclusion o mo e han one chambe il e . In an a emp o s oke up he ha monics and inc ease he sensi i i y beyond 1 kHz in he use o wo chambe il e s in se ies, we also supplied he UPS wi h 300 VAC ins ead o 220 VAC and epea ed he measu emen o he scena io 6. Las ly, in o de no o clu e he pape wi h oo many g aphs, we gi e he co esponding absolu e impedance and cu en alues, which p oduce he de ia ions shown in he g aphs, only o one case o he UPS, no o all he es cases. Fig. 5. CE 101 es se up ins alled wi h esis o s, capaci o s and induc o s as sou ce impedance simula ion and he signal gene a o RF ou pu as EUT. Fig. 6. CE 101 es se up ins alled wi h he ha monic e e ence de ice as EUT. Fig. 7. CE 101 es se up ins alled wi h he UPS as EUT. TABLE I. UPS MEASUREMENT SCENARIOS A e he ins alla ion o he equi ed se ups, we comple ed he loop impedance measu emen s o each o hem. The equencies, a which he impedance measu emen was pe o med, we e decided h ough a p elimina y and quick emission es jus be o e he impedance measu emen . The p elimina y emission check ga e us peak alues and equencies o he impedance measu emen . In o de no o ge in con lic wi h he EUT emission equencies du ing he impedance measu emen , we sligh ly shi ed each de ec ed EUT emission equency le and igh and eco ded hese e ised equencies o he impedance measu emen . Fo example, i a de ice emi s a 150 Hz, 450 Hz, 850 Hz, 1.15 kHz, 1.55 kHz, 1.95 kHz, impedance measu emen s should be ca ied ou a 120 Hz, 180 Hz, 420 Hz, 480 Hz, 820 Hz, 880 Hz, 1.120 kHz, 1.180 kHz, 1.52 kHz, 1.58 kHz, 1.92 kHz, 1.98 kHz in o de no o collide wi h he EUT emission equencies bu also o be close o hem o mo e accu a e impedance measu emen s and co ec ion ac o s calcula ed in (1). IV. RESULTS The e i ica ion esul s o he impedance measu emen sys em a e p esen ed in Fig. 8. As obse ed in Fig. 8, he impedance measu emen sys em yields accep able ag eemen ha p o es i s us wo hiness. In his simple e i ica ion, as he e e ence alues, we di ec ly used he a ed alues o 0.5 Ω and 50 Ω whe eas we used he a ed alues and he heo e ical impedance equa ions o he capaci o (80 µF) and he induc o (430 µH). (a) (b) (c) (d) Fig. 8. Impedance measu emen e i ica ion wi h (a) he 0.5 Ω esis o , (b) he 50 Ω e mina o , (c) he 80 µF capaci o , (d) he 430 µH induc o . (a) (b) (c) Fig. 9. Impedance and loop cu en de ia ions o he signal gene a o RF ou pu used as EUT be ween he di e en sou ce impedance condi ions (a) 50 Ω e sus 80 µF, (b) 50 Ω e sus 430 µH, (c) 80 µF e sus 430 µF. A e he impedance e i ica ion, he loop cu en and impedance de ia ion esul s o he signal gene a o RF ou pu used as a dummy EUT in di e en sou ce impedance condi ions a e gi en in Fig. 9. As clea ly obse ed in Fig. 9, al hough he impedance esul s a e signi ican ly dis inc in di e en sou ce en i onmen s, he loop cu en de ia ion accep ably ollows he loop impedance de ia ion pe g aph, which e i ies he p oposed me hod in an ideal es en i onmen . In each g aph, he impedance de ia ion signi ies he di e ence in loop impedance magni udes in decibels be ween wo di e en sou ce impedance condi ions while he cu en de ia ion shows he same o he loop cu en lowing in he es ci cui s. Fo example, in Fig. 9 (a), while a de ia ion o 5 dB in loop impedance occu s due o he change o he dummy sou ce impedance condi ion om 50 Ω o 80 µF behind he LISNs, he loop cu en de ia es in a simila manne as he loop impedance. The consis en change in bo h he loop impedance and cu en de ia ions may be ega ded as a good s a o he p oposed me hod. I should be ei e a ed he e ha he impedance de ia ion is in ac he co ec ion ac o be ween he wo cases pe g aph. Fig. 10. Loop impedance and cu en de ia ions wi h espec o 50 Ω o he sou ce impedance condi ions: 6.6 Ω, 13.3 Ω, 26.6 Ω o he ha monic e e ence de ice. In he same ein, he ha monic e e ence de ice esul s a e p esen ed in Fig. 10 in he ange o 30 Hz – 10 kHz. Again, he e is good ag eemen in he impedance and cu en de ia ion esul s wi h espec o 50 Ω. When we change he dummy sou ce impedance om 6.6 Ω o 26.6 Ω wi h i egula s eps and compa e he esul s wi h he 50 Ω esul s, he loop impedance and cu en de ia ion cu es change in ha mony wi h each o he . To exempli y his, when we change he dummy sou ce impedance om 6.6 Ω o 50 Ω, i yields a de ia ion o a ound 14 dB in bo h he impedance and cu en alues, as seen in Fig. 10. The good ag eemen in impedance and cu en de ia ions also exis s in he o he impedance ansi ions om 13.3 Ω and 26.6 Ω o 50 Ω. (a) (b) (c) (d) (e) Fig. 11. Impedance and loop cu en de ia ions wi h espec o he s anda d se up (scena io 1) o he UPS supplied by 220 VAC o he sou ce condi ions: (a) scena io 2, (b) scena io 3, (c) scena io 4, (d) scena io 5, (e) scena io 6. A e he p elimina y esul s ob ained wi h he signal gene a o RF ou pu and ha monic e e ence sou ce ha may be ega ded as ideal o dummy EUTs, ul ima ely he esul s o he UPS selec ed as an ac ual piece o EUT a e p esen ed in Fig. 11 - 12. In his s ep, he s anda d CE101 es se up (scena io 1) ha only comp ises he EUT and he LISNs was selec ed as he e e ence se up. In his s anda d se up, he LISNs we e di ec ly connec ed o ou clean AC powe sou ce wi hou any chambe il e s. In all he o he condi ions (scena ios 2 - 6), he chambe il e s we e placed be ween he LISNs and he powe supply in o de o change he sou ce impedance and c ea e di e en es condi ions. In Fig. 11 (a), we obse e ha he comme cial chambe il e inse ed be ween he LISNs and he powe supply in scena io 2 does no ma kedly change he sou ce impedance and does no p oduce signi ican impedance de ia ion wi h espec o he s anda d CE101 es se up. Simila ly, he cu en does no change in he wo es condi ions. When we s udy Fig. 11 (b), we see ha inse ing ou in-house il e 1 be ween he LISNs and he powe supply in scena io 3 changes he loop impedance o he CE101 es se up. I also causes he loop cu en o de ia e simila ly. Tha means ha we can calcula e he loop cu en , also called emission le el, in a a ge ed es en i onmen by jus measu ing he loop impedance alues o he e e ence and he a ge ed es en i onmen . In ou case he e, e en i we did no measu e he loop cu en alue in he a ge ed en i onmen (scena io 3), we could es ima e i by using he loop cu en in he e e ence en i onmen (scena io 1) and he impedance de ia ion conside ed as he co ec ion ac o calcula ed in (1). We ob ain ano he good consis ency in Fig. 11 (c). The in-house il e 2 inse ed be ween he LISNs and he powe supply in scena io 4 p oduces a de ia ion qui e equi alen o he de ia ion p oduced by he in-house il e 1. (a) (b) Fig. 12. (a) Impedance and loop cu en de ia ions wi h espec o he s anda d se up (scena io 1) o he UPS supplied by 300 VAC o he sou ce impedance condi ion: scena io 6, (b) absolu e impedance and loop cu en alues which a e used o de ia ion calcula ion. When we place he comme cial and in-house il e s in se ies be ween he LISNs and he powe supply in scena io 5, i p oduces an impedance de ia ion isually alike o scena ios 3 and 4 bu wi h a highe de ia ion a highe equencies. As clea ly seen in Fig. 11 (d), e en a 1.3 kHz, he impedance de ia ion in scena io 5 eaches -6 dB bu we we e no able o eco d he ha monic cu en s beyond 1.3 kHz as hey become e y low and useless wi h he inse ion o he wo chambe il e s in se ies. In Fig. 11 (e), a simila g aph is ob ained when he in-house il e 1 and in-house il e 2 a e placed in se ies be ween he LISNs and he powe supply in scena io 6. Also, he e we had o limi he equency ange o 1.1 kHz as he magni udes o he ha monics sagged signi ican ly beyond 1.1 kHz. Finally, he esul s o he UPS supplied by 300 VAC ins ead o 220 VAC in an a emp o s eng hen he ha monics a e shown in Fig. 12 (a) along wi h he absolu e impedance and cu en alues in Fig. 12 (b) jus o in o ma ion. When we inc ease he supply ol age om 220 VAC o 300 VAC, he s eng h o he ha monics seems o inc ease bu he s abili y o he ha monics seems o wo sen. As a esul , as seen in Fig. 12 (a), when he supply ol age is inc eased o 300 VAC, accep able ha monics s a s o occu up o 2 kHz bu wi h highe luc ua ion. This inal esul shows he e ec i eness o he p oposed me hod as he wo cu es a e easonably ollowing each o he in Fig. 12 (a) up o 2 kHz despi e he ema kable luc ua ion in he ha monic le els. V. CONCLUSIONS AND FUTURE WORK The expe imen al esul s suppo he e ec i eness o he p oposed me hod, ha is, low equency emission es ing can be signi ican ly imp o ed h oughou li e impedance measu emen s. When he loop impedance and cu en alues a e known o a ce ain es si e, he measu ed emission le els, namely he loop cu en , can be es ima ed o o he si es/condi ions as long as he loop impedance is also known a ha a ge ed si e. Al e na i ely, emission esul s ob ained in di e en es en i onmen s may be scaled o a de ined impedance alue, such as 50 Ω, o ha monise emission esul s ob ained om di e en es en i onmen s and make hem compa able. E en a s anda d limi co esponding o he de ined impedance can be de e mined o s anda disa ion and sou ce impedance-independen es esul s. The p omising esul s encoun e ed p o ide con idence in he p oposed app oach; howe e , he me hodology emains a he ea ly s ages. The esea ch mus be u he eplica ed and ex ended since he expe imen s conduc ed so a only co e ed h ee EUT ypes. We will expand he scope o mo e EUT ypes and a emp o gene alise his p ocedu e. Addi ionally, we will ecommend ha emission es esul s in he low equency ange, e.g. CE101 es esul s, should be accompanied by and epo ed oge he wi h g id o powe sou ce impedance alues seen by he EUT and aken a he ime o he es . This would allow acking, explaining and co ec ing disc epancies in emission es esul s be ween es labo a o ies. The impedance measu emen o he g id o powe sou ce seen by he EUT can be easily pe o med by means o he CS101 es sys em, as in oduced in his pape . Al hough we always ocused on he o e all loop impedance in his esea ch, only he sou ce side impedance o e en only he EUT impedance, i eques ed, can be measu ed by jus mo ing he ol age p obe om he ou pu o he coupling ans o me o he LISN ou pu s o he EUT inpu . We expec his me hod will g ow in ma u i y and e en ually could be s anda dised. Mo eo e , he knowledge and expe ience acqui ed in his esea ch may also be ex ended o comme cial ha monic measu emen s ca ied ou as pe IEC 61000-3-2 [14] o IEC 61000-3-12 [15] in u u e applica ions. ACKNOWLEDGMENT This esea ch is pe o med in he scope o he p ojec “21NRM06 EMC-STD Me ology o eme ging elec omagne ic compa ibili y s anda ds”. The p ojec (21NRM06 EMC-STD) has ecei ed unding om he Eu opean Pa ne ship on Me ology, co- inanced by he Eu opean Union’s Ho izon Eu ope Resea ch and Inno a ion P og amme and by he Pa icipa ing S a es. REFERENCES [1] “Requi emen s o he Con ol o Elec omagne ic In e e ence Cha ac e is ics o Subsys ems And Equipmen ”, Depa men o De ence USA, MIL-STD-461G, 2015. [2] A. Ka aali, E. Akpina , O. O. Gu sahbaz and B. Ozbey, "The E ec s o Shielded Room Powe Line Fil e s on CE101, CE102 and CS101 Tes Resul s," 2022 In e na ional Symposium on Elec omagne ic Compa ibili y – EMC Eu ope, Go henbu g, Sweden, 2022, pp. 691- 696, doi: 10.1109/EMCEu ope51680.2022.9901139. [3] S. Çaki , O. Sen, M. Çina and M. Çe in as, "Al e na i e conduc ed emission measu emen s o indus y," 2014 In e na ional Symposium on Elec omagne ic Compa ibili y, Go henbu g, Sweden, 2014, pp. 1037-1042, doi: 10.1109/EMCEu ope.2014.6931055. [4] O. Sen, S. Cakı , M. Cına , M. Pous, F. Sil a and M. Ce in as, "Al e na i e conduc ed emission measu emen s on mains wi hou LISNs," in IEEE Elec omagne ic Compa ibili y Magazine, ol. 4, no. 4, pp. 58-65, Fou h Qua e 2015, doi: 10.1109/MEMC.2015.7407180. [5] S. Caki , M. Oz u k, O. Sen, B. Tek as, S. Acak and M. Ce in as, "MIL STD 46IF CS101 es ing and powe equency cancela ion," 2016 Asia-Paci ic In e na ional Symposium on Elec omagne ic Compa ibili y (APEMC), Shenzhen, China, 2016, pp. 855-857, doi: 10.1109/APEMC.2016.7522889. [6] S. Caki , O. Sen, M. Oz u k, M. Celep and T. Aca e , "In es iga ion o undesi ed ipple ol age ac oss powe sou ce side and solu ions in mili a y low- equency immuni y es s," in IEEE Elec omagne ic Compa ibili y Magazine, ol. 8, no. 3, pp. 65-73, 3 d Qua e 2019, doi: 10.1109/MEMC.2019.8878239. [7] S. Caki , O. Sen, M. Oz u k and M. Celep, "In luence o Injec ion Poin Selec ion on Mili a y Low F equency Immuni y Tes Resul s," 2019 ESA Wo kshop on Ae ospace EMC (Ae ospace EMC), Budapes , Hunga y, 2019, pp. 1-5, doi: 10.23919/Ae oEMC.2019.8788952. [8] P. T. Jensen and P. Da a i, "Powe Con e e Impedance and Emission Cha ac e iza ion Below 150 kHz," 2021 IEEE In e na ional Join EMC/SI/PI and EMC Eu ope Symposium, Raleigh, NC, USA, 2021, pp. 255-260, doi: 10.1109/EMC/SI/PI/EMCEu ope52599.2021.9559177. [9] S. Caki , M. Oz ü k, B. Tek as, O. Şen, S. Acak and M. Pous, "FFT- based ime domain solu ion o powe equency issue o CS101 es ing o mili a y and ae ospace equipmen ," 2018 IEEE In e na ional Symposium on Elec omagne ic Compa ibili y and 2018 IEEE Asia- Paci ic Symposium on Elec omagne ic Compa ibili y (EMC/APEMC), Sun ec Ci y, Singapo e, 2018, pp. 177-182, doi: 10.1109/ISEMC.2018.8393762. [10] S. Caki , O. Sen and M. Oz u k, "In es iga ion o Ripple Vol age Ac oss Capaci o in Mili a y CS101Tes by Using FFT -Based Time Domain Solu ion," 2018 IEEE Symposium on Elec omagne ic Compa ibili y, Signal In eg i y and Powe In eg i y (EMC, SI & PI), Long Beach, CA, USA, 2018, pp. 82-87, doi: 10.1109/EMCSI.2018.8495307. [11] “Time Domain EMC Emissions Measu emen Sys em”, Final Repo , AY4489, May 2004. Online:h ps://www.o com.o g.uk/__da a/asse s/pd _ ile/0019/40348/ imedomainemc.pd [12] Ba le , M, “Smoo hing Pe iodog ams om Time Se ies wi h Con inuous Spec a”, Na u e (London), Vol. 161, pages 686-687, 1948. [13] P. Welch, "The use o as Fou ie ans o m o he es ima ion o powe spec a: A me hod based on ime a e aging o e sho , modi ied pe iodog ams," in IEEE T ansac ions on Audio and Elec oacous ics, ol. 15, no. 2, pp. 70-73, June 1967, doi: 10.1109/TAU.1967.1161901. [14] IEC 61000-3-2:2014 Elec omagne ic compa ibili y (EMC) Limi s. Limi s o ha monic cu en emissions (equipmen inpu cu en ≤16 A pe phase). [15] IEC 61000-3-12:2011 Elec omagne ic Compa ibili y (EMC) - Limi s Fo Ha monic Cu en s P oduced By Equipmen Connec ed To Public Low-Vol age Sys ems Wi h Inpu Cu en >16 A And ≤ 75 A Pe Phase