Good P ac ice Guide on Making Rec angula
Wa eguide Connec ions a F equencies abo e
100 GHz
Tho s en P obs , Ka s en Kuhlmann, Nick Ridle , James Wa s
July, 2019
This documen and all pa s con ained he ein a e p o ec ed by copy igh
and a e subjec o he C ea i e Commons use license CC BY-ND 4.0
(h ps://c ea i ecommons.o g/licenses/by-nd/4.0/deed.en).
;
Sugges ion o he quo a ion o he e e ences:
P obs , Tho s en ; Kuhlmann, Ka s en ; Ridle , Nick ; Wa s, James.
Good P ac ice Guide on Making Rec angula Wa eguide Connec ions a
F equencies abo e 100 GHz, 2019. Physikalisch-Technische Bundesans al .
DOI: h ps://doi.o g/10.7795/530.20190805
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
Acknowledgemen
The au ho s acknowledge suppo by he Eu opean Me ology P o-
g amme o Inno a ion and Resea ch (EMPIR) P ojec 17SIP08 “New
Wa eguide In e aces o Te ahe z Technologies”. The EMPIR p og am
is co- inanced by he pa icipa ing coun ies and om he Eu opean
Union’s Ho izon 2020 esea ch and inno a ion p og am.
Con en s
1 In oduc ion 1
1.1 O e iew o ec angula wa eguide s anda d documen s . . . 1
1.2 Wa eguide designa ion and compa ibili y . . . . . . . . . . . 3
1.3 Rec angula wa eguide basics . . . . . . . . . . . . . . . . . . 3
2 The IEEE 1785 se ies o s anda ds 5
2.1 IEEE S d 1785.1-2012 . . . . . . . . . . . . . . . . . . . . . . 6
2.2 IEEE S d 1785.2-2016 . . . . . . . . . . . . . . . . . . . . . . 6
2.3 IEEE S d 1785.3-2016 . . . . . . . . . . . . . . . . . . . . . . 7
3 Pe o ming p ecise measu emen s 9
3.1 P epa a ions ........................... 9
3.2 Measu emen se -up . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 Somep ac ical ips........................ 13
3.3.1 Use o a p ecision wa eguide sec ion as a es in e ace 14
3.3.2 Di e en wa eguide ape u es . . . . . . . . . . . . . . 14
3.3.3 Wa eguide o coaxial adap e s . . . . . . . . . . . . . 14
3.4 Example Measu emen s . . . . . . . . . . . . . . . . . . . . . 15
3.4.1 Measu emen s o 75 o 110 GHz:
WR10 / WM-2540 / R 900 / WG 27 . . . . . . . . . . 16
3.4.2 Measu emen s o 220 o 330 GHz:
WR3 / WM-864 / R 2.6k / WG 32 . . . . . . . . . . . 21
4 So wa e 23
4.1
So wa e o Unce ain y Calcula ion o Wa eguide Connec ions
23
Re e ences 24
h ps://doi.o g/10.7795/530.20190805 i
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
Pu pose
A equencies o app oxima ely 100 GHz and abo e, ec angula me allic
wa eguide is o en he p e e ed ansmission medium o making eliable,
p ecision, measu emen s. A p e equisi e o hese ypes o measu emen s is
he use o he co ec ypes o wa eguide in e ace, and, he need o ollow
he co ec ope a ing p ocedu es. This documen is aimed a people in e -
es ed in making ep oducible measu emen s wi h ela i ely low measu emen
unce ain y, in ec angula wa eguide, a hese equencies. I can be con-
side ed as a suppo ing documen o exis ing s anda ds ha a e a ailable
o wa eguide and wa eguide in e aces used a hese equencies (e.g. as
published by IEEE, IEC, MIL, EIA, e c). This documen concen a es on
ec angula wa eguides. Howe e , many aspec s ha a e p esen ed migh
also be applicable o ci cula wa eguides.
h ps://doi.o g/10.7795/530.20190805 ii
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
1 In oduc ion
1.1 O e iew o ec angula wa eguide s anda d documen s
Today he IEC and IEEE a e he wo main in e na ional s anda disa ion
bodies o ec angula wa eguides o use a equencies abo e 100 GHz.
O he s anda disa ion bodies, such as Uni ed S a es Mili a y (MIL), he
Elec onic Indus ies Alliance (EIA) o he Uni ed Kingdom Minis y o
De ence (MoD), a e also e e enced by some manu ac u e s, al hough some
o hese documen s a e no longe main ained. Table 1 lis s he la es edi ions
o hese documen s.
S anda d Dimension In e ace
Pub-
lica-
ion
yea
max
/ GHz
MIL-DTL-85/3D X X 2012 325
S d1785.1-2012 [1] X X 2012 3300
IEC 60153-2:2016 [2] X X 2016 3300
EIA RS-261-B:1979 X X 1979 325
MIL-DTL-3922/67E
w/Amendmen 1[3] X2014 110
IEEE S d1785.2-2016 [4] X2016 3300
IEC 60154-2:2016 [5] X2016 3300
Table 1. Selec ion o exis ing s anda ds o ec angula wa eguides.
Usually, one s anda d p o ides in o ma ion conce ning he equency bands
and he associa ed wa eguide ape u e sizes, and ano he s anda d desc ibes
he wa eguide in e aces (also e e ed o as langes). In he 5
h
column o
Table 1,
max
indica es he highes equency he s anda d suppo s. In 2012
and 2016 IEEE and IEC published new s anda ds o co e equency bands
up o he e ahe z equency egion [1], [2], [4], [5].
Figu e 1 shows an example o a wa eguide lange used a millime e(mm)-
wa e equencies and abo e. Usually, he wa eguide opening (ape u e) is
cen ed, while he alignmen and connec ion mechanisms (i.e. dowels, holes,
and h eaded holes) a e placed a ound he ape u e.
A mo e comple e o e iew abou exis ing wa eguide sizes and langes can be
ound in [6]–[9].
h ps://doi.o g/10.7795/530.20190805 1 o 25

Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
an i-
cocking
ing
align-
men pin
h eaded
hole
WG ap-
pe u e
p ecision
alignmen
holes
boss
align-
men hole
ab
Fig. 1. Example lange o ec angula wa eguide.
Wa eguide Designa ion
IEEE MoD IEC EIA / GHz
WM- WG R WR
2540 27 900 10 75-110
2032 28 1.2k 8 90-140
1651 29 1.4k 7 110-170
1295 30 1.8k 5 140-220
1092 31 2.2k 4 170-260
864 32 2.6k 3 220-330
710 - 3.2k - 260-400
570 - 4k - 330-500
470 - 5k - 400-600
380 - 6.2k - 500-750
310 - 7.4k - 600-900
250 - 9k - 750-1100
200 - 12k - 900-1400
164 - 14k - 1100-1700
130 - 18k - 1400-2200
106 - 22k - 1700-2600
86 - 26k - 2200-3300
Table 2.
O e iew o ec angula wa eguide designa ions o selec ed equencies[6].
h ps://doi.o g/10.7795/530.20190805 2 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
1.2 Wa eguide designa ion and compa ibili y
Table 2 gi es an o e iew o some common wa eguide designa ions. The
ecommended equency anges speci ied in he di e en s anda ds migh
a y sligh ly, hus ounded alues a e used he e.
Mos s anda dised langes om IEEE and IEC a e mechanically compa ible
wi h olde designs (e.g. om MIL, EIA, MoD, e c.) o he same ype o
lange and compa ible wi h each o he , hough he elec ical pe o mance
migh be signi ican ly deg aded [10]. One excep ion is IEEE 1785.2c, which
is a plug and jack design. Only he plug ype design is compa ible wi h he
o he langes.
In p ac ice, many manu ac u e s o wa eguide componen s o use a equen-
cies abo e 100 GHz ha e chosen o mi iga e his pe o mance deg ada ion by
de ia ing om he s anda d designs. This is ypically achie ed by inc easing
he diame e o he alignmen pins o educing he diame e o he alignmen
holes. Whils hese non-s anda d langes can s ill be ma ed wi h each o he
and wi h s anda dised lange designs, some combina ions o manu ac u e s’
langes will no ma e a all due o he impac o ole ances on he c i ical
dimensions. I i is no known which s anda ds a pai o langes ollows, one
mus make he connec ion e y ca e ully.
Mos wa eguide in e aces ollow a simila connec ion s a egy. The e is
basically one lange design o se e al equency bands, and he alignmen
is ealised ia holes and dowels wi h a ce ain p ecision. Howe e , he e
a e some excep ions, e.g. lange ype G (IEC 60154-2:2016 [5]). In IEEE
1785.2-2016, he e a e ac ually h ee di e en langes designs, and he align-
men mechanisms a e somewha di e en when compa ed o each o he , o
o lange designs gi en in o he s anda ds. This will be desc ibed in de ail in
Sec ion 2.2.
A mo e comple e o e iew o lange compa ibili y can also be ound in [6],
[9].
1.3 Rec angula wa eguide basics
In his sec ion, some equa ions a e gi en ela ing o he p opaga ion cha ac-
e is ics o hese wa eguides. This kind o in o ma ion is usually p o ided by
wa eguide manu ac u e s.
The cu -o equency c o he ec angula wa eguide [1] is
c=c
√ ·
1
2·a(1)
whe e
c
: is speed o elec omagne ic wa es in acuum, de ined as 299 792
458 m/s
 : is ela i e pe mi i i y
h ps://doi.o g/10.7795/530.20190805 3 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
a: is wa eguide b oad wall dimension
The a enua ion cons an αcan be app oxima ed [1] wi h
α= 0.023273 · ρ
ρ0·
1
b√a·
c2
+2·b
a
q
c· 
c2
−1
dB/cm (2)
whe e
ρ: is esis i i y o he wa eguide conduc o
ρ0: is e e ence esis i i y = 17.241 nΩ·m
a: is wa eguide b oad wall dimension in mm
b: is wa eguide na ow wall dimension in mm
c: is cu -o equency in GHz
: is equency a which a enua ion cons an is calcula ed in GHz
Equa ion (2) does no hold o hinly pla ed su aces (e.g. whe e he pla ing
hickness is less han wo imes he skindep h) and also neglec s any e ec s
due he su ace oughness o he wa eguide o o he de ec (e.g. c acks o
gaps in he in e nal co ne s o he wa eguide). The skindep h [11] is
δ= ρ
π µ = 2ρ
ωµ =1ρ
RS
(3)
whe e
µ: is pe mi i i y
RS: is su ace esis ance
G ea ca e should be aken in using his equa ion o wa eguides whe e
he wa eguide c oss sec ion is no o med om a single conduc o (e.g.
wa eguides o med om a machined channel and a la co e ). Impe ec
conduc ion a he joins o hese pa s can gi e ise o signi ican ly g ea e
a enua ion.
The in o ma ion gi en in his sec ion is only accu a e o single mode ope -
a ion and o he i s
T
ans e se
E
lec ic mode TE
10
. This means, ha he
elec ic ield is ans e se o he di ec ion o p opaga ion, while he magne ic
ield has componen s in he di ec ion o p opaga ion. Field illus a ions can
be ound e.g. in [11].
The ield o ien a ion o he TE
10
mode is also he eason o he naming o
he wo e e ence planes E-plane and H-plane in ec angula wa eguides (see
Figu e 2).
The e ms E-plane and H-plane a e also used in an enna measu emen s
and o o he mic owa e de ices o indica e he o ien a ion o he pola isa-
ion o o he elec omagne ic adio wa es.
h ps://doi.o g/10.7795/530.20190805 4 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
E-plane
H-plane
a
b
;
Fig. 2. Re e ence planes in ec angula wa eguides.
2 The IEEE 1785 se ies o s anda ds
A a ound he beginning o his cen u y, he e was a signi ican inc ease in
use o he millime e-wa e pa o he spec um o comme cial applica ions
in elec onics, ma e ials science and communica ions. In esponse o his
inc ease in usage, comme cial es equipmen g adually became a ailable.
Companies such as OML [12] o RPG [13] s a ed de eloping accesso ies
o ec o ne wo k analyse s ha enabled he ope a ing equency o be
ex ended abo e 110 GHz [14]. These measu emen capabili ies we e ex ended
subsequen ly o a leas 500 GHz [15]. O he companies, such as VDI [16],
con inued his end, de eloping sys ems ha ope a ed o beyond 1 THz [17].
Du ing he i s decade o his cen u y, he e was a ealisa ion ha knowledge
and s anda disa ion o wa eguide a hese equencies was a he limi ed
[18]. Schemes we e subsequen ly p oposed o ex end wa eguide sizes o co e
hese millime e and submillime e-wa e equencies [19]–[21]. Howe e ,
none o hese p oposed wa eguide sizes had been s anda dised o comple ely
accep ed by he end-use communi y. This led o he ini ia ion o an IEEE
s anda disa ion ac i i y, s a ed in 2008, o p o ide s anda dised wa eguide
sizes o use a hese equencies. A he same ime, i was widely ecognised
ha he elec ical and mechanical pe o mance o exis ing wa eguide langes
was inadequa e o use a hese equencies. The IEEE s anda disa ion
ac i i y aimed o add ess his issue as well.
The IEEE S anda ds Associa ion se up and launched he Wo king G oup
P1785. Beginning in 2008, h ee s anda ds co e ing (i) he wa eguide
sizes, (ii) wa eguide in e ace, and (iii) ypical unce ain y speci ica ions
o measu emen s a hese equencies we e de eloped. This esul ed in he
publica ion o he ollowing h ee s anda ds:
(i)
1785.1-2012: “IEEE S anda d o Rec angula Me allic Wa eguides
and Thei In e aces o F equencies o 110 GHz and Abo e—Pa 1:
F equency Bands and Wa eguide Dimensions”
(ii)
1785.2-2016: “IEEE S anda d o Rec angula Me allic Wa eguides
and Thei In e aces o F equencies o 110 GHz and Abo e—Pa 2:
h ps://doi.o g/10.7795/530.20190805 5 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
RCVR
A IN
RCVR
R1 IN
RCVR
R2 IN
RCVR
B IN
P1 P2P3 P4
1
2
4
2
5
66 7
8 8
10
7 6 6
9 9
10
RF IN
MEAS
OUT
MEAS
OUT
REF
OUT
REF
OUT
RF INLO IN
LO IN
3
Fig. 5.
Al e na i e schema ic measu emen se -up wi h 4-po VNA and equency
ex ende s.
1: 4-po VNA
2: Adap e 2.4 mm jack →3.5 mm jack
3: 1.85 mm e mina ion
4: Adap e NMD2.4 mm plug →NMD3.5 mm jack
5: Powe Spli e 3.5 mm jack
6: Cable 2.4 mm plug →2.92 mm plug
7: Cable 2.92 mm plug →2.92 mm plug
8: Cable 3.5 mm plug →3.5 mm plug
9: F equency Ex ende
10 : Adap e WM-2540 →WM-2540
how all componen s and cables we e a anged and whe he he wa eguide
connec ions we e done in ho izon al o e ical manne .
I only 1-po measu emen s a e equi ed, i migh be ad an ageous o use
a e ical se -up. Thus, g a i y e ec s should no in oduce any sys ema ic
in luence on he wa eguide connec ions. A e ical se -up can be achie ed
by using a wa eguide bend o by e ically posi ioning he ex ende head.
Fo he la e , a cus omized ix u e migh be equi ed. Fo bo h ho izon al
and e ical a angemen s, one should aim o ha e a mechanically s able
se -up: no unnecessa y mo emen s o ib a ions. Schema ic d awings o
wo di e en se -ups a e gi en in Figu e 7.
Depending on he manu ac u e , he in e nal VNA se ings e.g. AGC (au-
oma ic gain con ol) can in luence he o e all measu emen unce ain y.
The e o e, one should check hese se ing be o ehand. This is e en mo e
impo an i he VNA i mwa e is no used o he calib a ion. I he uncal-
ib a ed ( aw) da a is measu ed, e.g. o use wi h cus om calib a ion ou ines,
he ope a o should check he ollowing:
1. Recei e se ings (AGC, …)
2. Possible p e-calib a ions
h ps://doi.o g/10.7795/530.20190805 12 o 25

Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
MEAS IN REF IN REF IN MEAS IN
P1 P2
1
RFM M
RRRF
LOLO
10 MHz
REF
OUT
LAN 1
LAN
REF
IN
OUT
3
2
3
5
4
5
4
3 3
6 6
7 7
8
8
910
11 12
Fig. 6.
Schema ic measu emen se -up wi h 2-po VNA, syn hesize and equency
ex ende s.
1: 2-po VNA
2: Signal gene a o
3: Cable 2.4 mm plug →2,92 mm plug
4: Cable 2,92 mm plug →2,92 mm plug
5: Adap e 2.4 mm jack →3.5 mm jack
6: F equency Ex ende
7: Adap e R900 →R900
8: Cable 3.5 mm plug →3.5 mm plug
9: Powe Spli e 3.5 mm jack
10 : Adap e 3.5 mm plug →3.5 mm plug
11 : BNC Cable
12 : E he ne Cable
3. Co ec eco ding o swi ch e ms
3.3 Some p ac ical ips
Much o he in o ma ion gi en in [23] (chap e 8: Bes measu emen p ac ice
and p ac ical ad ice) can also be applied o wa eguide measu emen s abo e
100 GHz. This sec ion ocuses on good measu emen p ac ice o ypical
wa eguide applica ions.
h ps://doi.o g/10.7795/530.20190805 13 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
(a) Typical ho izon al se -up. (b) Typical e ical se -up.
Fig. 7. Ex ende head posi ions: (a) ho izon al, and (b) e ical.
3.3.1 Use o a p ecision wa eguide sec ion as a es in e ace
O e ime and wi h use, he wa eguide in e aces o VNA equency ex ende s
can become damaged o wo n, and his impac s di ec ly on measu emen
epea abili y. I is good p ac ice o i sho p ecision wa eguide s aigh
sec ions o he equency ex ende es po s since hese can easily be emo ed
o inspec ion and calib a ion wi hou in alida ing manu ac u e s’ wa an ies.
This p ocedu e is well known om coaxial measu emen s. The addi ional
coaxial adap e is o en called a ”connec o sa e ” o ”in e ace sa e ”.
3.3.2 Di e en wa eguide ape u es
I he same lange is used, i is possible o connec wa eguides wi h di e en
ape u e sizes. This may e en be in ended in some applica ions, like e.g.
o he VDI powe me e PM5 [16]. The PM5 is equipped wi h a WR-10
wa eguide, bu i is possible o measu e powe le els a equencies much
highe han 110 GHz (e en up o 3 THz).
Abo e a ce ain equency howe e , mo e han one wa eguide mode can
p opaga e in he la ge ape u e, and i becomes di icul o p edic how
much ene gy o he ac ual signal is dis ibu ed o which mode. This may
e en change o each new lange connec ion (di e en exci a ion condi ions),
and he epea abili y o such measu emen s should be checked e y ca e ully.
In gene al, i is ecommended o use WG ape u es o he same size o o
in oduce a WG ape . This should minimise coupling in o unwan ed modes,
bu does no comple ely elimina e i .
3.3.3 Wa eguide o coaxial adap e s
Fo ’no mal’ coaxial o wa eguide de ices i should no ma e , a which
o ien a ion hey a e connec ed o he es po s. This is di e en o coaxial
o wa eguide adap e s. The TEM ( ans e se elec omagne ic) mode o
he coaxial line is symme ical o he inne conduc o , he TE ( ans e se
elec ic) mode o he wa eguide is no . I he ansmission coe icien o a
h ps://doi.o g/10.7795/530.20190805 14 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
wa eguide o coaxial adap e is measu ed, he phase will change by 180 °, i
he wa eguide connec ion o he es po is o a ed by 180 °. The e lec ion
coe icien emains unchanged. This e ec poses usually no p oblem, because
in da a shee s o such adap e s o en only he magni ude o he inse ions
loss is gi en. I , howe e , a calib a ion ce i ica e (o simila documen )
includes all complex S-Pa ame e s o a coaxial o wa eguide adap e , he
wa eguide lange o ien a ion du ing measu emen mus also be s a ed in such
a documen .
3.4 Example Measu emen s
In his sec ion, some WG measu emen s a e p esen ed and discussed. The
ocus lies on he epea abili y o lange connec ions and he d i in luences
o he measu emen equipmen . The langes ha a e used a e:
•
UG-387, i.e. he ype o lange ha mos measu emen de ices a e
equipped wi h.
• IEEE 1785.2a, p ecision lange o equencies up o THz.
The o iginal UG-387 lange design does no ha e any inne p ecision alignmen
holes. Bu , o achie e be e epea abili y, some manu ac u e s added added
inne alignmen holes be o e IEEE o IEC published he new s anda ds. The
dimension and ole ance o hese holes and associa ed dowels a e o en no
he same, be ween di e en manu ac u e s, hus an ope a o mus be e y
ca e ul abou connec ing langes ha look simila , a i s glance, o a oid
damage due o hese dimensional di e ences.
To cha ac e ise a lange in e ms o epea abili y, one can do an analysis o
epea ed connec ions o s able de ices unde es (DUT), e.g. a ma ched
load o a sho [23]. Bu i is also possible o es ima e he epea abili y based
on he ole ance o he alignmen mechanisms o he lange.
The maximum misalignmen o he UG-387 lange is app oxima ely 150 µm
in bo h he H- and E-plane, and he maximum angula misalignmen is 1.2 °.
Fo he IEEE 1785.2a lange, he maximum misalignmen is 25 µm in he H-
plane, 20 µm in he E-plane, and he maximum angula misalignmen is 0.4 °.
Wi h his in o ma ion and mode n simula ion ools, he wo s case e u n
loss can be calcula ed [4], [27]. Table 4 shows hese wo s case e u n loss
UG-387 IEEE.2a
WR 10 / WM-2540 ≈-30 dB -60 dB
WR 03 / WM-864 ≈-12 dB -39 dB
WM-570 ≈-8 dB -32 dB
Table 4.
Theo e ical lange pe o mance o selec ed WG dimensions o UG-387
(no modi ied, wi hou inne p ecision holes) and IEEE S d. 1785.2:2016.
h ps://doi.o g/10.7795/530.20190805 15 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
alues o s anda dised lange connec ions. This able shows ha he UG-387
lange is no eally sui able o use a equencies abo e app oxima ely 110
GHz. The epea abili y should usually be be e han he wo s case e u n
loss. In he ollowing, i is shown, ha his is no always he case.
3.4.1 Measu emen s o 75 o 110 GHz:
WR10 / WM-2540 / R 900 / WG 27
The equency band 75-110 GHz is he lowes band suppo ed by he IEEE
s anda d, bu he UG-387 lange is usually p ecise enough o ge a easonable
good epea abili y and ep oducible measu emen esul s o hese equencies
and is he e o e s ill widely used.
In Figu e 8 he epea abili y is shown o a ma ched DUT o a ho izon al
and a e ical measu emen se -up ( o educe g a i y o se s) and wi h and
wi hou addi ional inne alignmen dowels used.
75 80 85 90 95 100 105 110
0
2
4
·10−4
F equency / GHz
Repea abili y
wi h dowel ( e ical) no dowel ( e ical)
wi h dowel (ho ion al) no dowel (ho ion al)
Fig. 8.
Repea abili y e alua ion wi h ou measu emen s o e ical and ho izon al
posi ion wi h and wi hou alignmen dowels.
The epea abili y was calcula ed as desc ibe in [23]. I is ob ained om
epea ed measu emen s o a s able DUT and calcula ing he maximum
di e ences, aking bo h he eal and imagina y componen s in o accoun .
This is a e y conse a i e app oach and ou lie sensi i e, bu i acknowledges
he ac ha he epea abili y can s ongly a y om one lange pai o
ano he . As can be seen, he di e en cases yield e y simila epea abili y
esul s and a e always be e han 0.0316, (≈-30 dB, see Table 4).
Fo a connec ion wi h he UG-387 lange ou sc ews mus be igh ened.
Because in some se -ups one o mo e sc ews migh be di icul o each (o
due o ime easons) some ope a o s do no use all ou sc ews. This is likely
o ha e a signi ican in luence no only on he epea abili y, bu also on he
measu ed alue, as is shown in Figu e 9.
One should always use all ou sc ews and also a sui able o que o igh en
he sc ews. The la e can be a di icul ask, because he o que is no
s anda dised, and manu ac u e s speci y di e en alues [24], [28]. The
h ps://doi.o g/10.7795/530.20190805 16 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
75 80 85 90 95 100 105 110
0.98
0.99
1
F equency / GHz
|S11|
loose sc ews; ixed sc ews
Fig. 9. Calib a ed e u n loss measu emen s o a lush sho -ci cui .
o que needed o p oduce a p ecise and ep oducible wa eguide connec ion
is a leas dependen on:
•
base ma e ial o he langes (e.g. coppe , be yllium coppe , b ass,
aluminium, e c.),
• hickness o he lange (i.e. he lange could be o med using a block)
• quali y o he h eaded holes and sc ews (di e en ic ion loss),
•
su ace ma e ial (o en se e al me al laye s, e.g. nickel, gold, sil e ,
e c.),
• su ace la ness,
• su ace oughness.
Fo a high quali y pai o langes (i.e. wi h la su ace and low su ace
oughness, e c.) a e y small o que is o en su icien o achie e a good
epea abili y o wa eguide connec ions. Bu , o equal impo ance as he
o que is he weigh o a DUT o ho izon al se -ups o he alignmen o a
second ex ende head o ho izon al se -ups (needed o 2-po measu emen s).
Bo h migh educe he e ec i e o que on he in e ace i sel e y much and
gi e he w ong imp ession, e.g. ha a high o que mus always be used.
In Figu e 10 he epea abili y is shown o wo o que alues (0.06 N
·
m and
0.58 N
·
m) as well as o he o que achie ed by an expe ienced ope a o . The
la e is es ima ed o be app oxima ely 0.3 N
·
m ( e i ied wi h a calib a ed
o que me e ).
Figu e 10 shows ha he epea abili y achie ed by he expe ienced ope a o
can be be e han ha achie ed using he speci ied o que alues. I also
shows ha mo e (o less) o que does no au oma ically mean a be e
connec ion. This is one eason why alues o o que o making wa eguide
connec ions a e no cu en ly speci ied in he s anda ds. Fo example, du ing
connec ion, an expe ienced ope a o can conside o he aspec s ha migh
impac he quali y o he connec ion – e.g. he weigh o he componen being
connec ed when igh ening he lange sc ews. Howe e , i is s ill usually
ecommended o use o que d i e s o achie e ep oducible esul s.
h ps://doi.o g/10.7795/530.20190805 17 o 25

Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
75 80 85 90 95 100 105 110
0.5
1
1.5
2
·10−2
F equency / GHz
Repea abili y
0.06 N·m; exp. ope a o ; 0.58 N·m
Fig. 10. Repea abili y measu emen s [23] o an o se -sho o di e en o ques.
When pe o ming epea abili y es s, one should no blindly do he s a is ical
analysis bu also in es iga e he single measu emen s o iden i y any possible
ou lie s caused by poo connec ions. Figu e 11 shows he di e ence o he
single e lec ion coe icien measu emen s
Γn
o he mean alue
Γall,mean
o
all epea abili y measu emen s o wo expe imen s wi h he same DUT
(sho -ci cui ). In Figu e 11(a), wo ou lie s (measu emen 3 and 4) can
be iden i ied. These should no be aken in o accoun o he epea abili y
calcula ion. I he numbe o emaining measu emen s is oo ew (a leas 4
o mo e should be used), one should epea he expe imen comple ely. In
Figu e 11(b), he epea ed expe imen (pe o med wi h mo e ca e) wi hou
ou lie s is shown.
All epea abili y measu emen s migh also be dis o ed due o:
• Noise,
• D i ,
• Cable mo emen s.
Depending on he measu emen scena io, 1-po measu emen s usually don’
equi e cable mo emen , he la e one can o en be a oided comple ely.
E en i no a comple e unce ain y budge is equi ed, he p ocedu e o ge
his a e gi en in [22], [23], one should s ill do some simple es s o quan i y
hese e ec s. Fo example o ge an idea how la ge he ins umen d i is,
one can do a se ies o measu emen s (e.g. one e e y 60 sec.) o a s able DUT
(wi hou econnec ing). In Figu e 12 he d i esul o such a measu emen
is shown o he linea e lec ion coe icien o a lush sho -ci cui .
The alues a e ob ained by simply calcula ing he di e ence o he i s
measu emen . The d i o 4 measu emen s (co esponds o 4 minu es)
a he beginning and a he end o a expe imen is nea ly iden ical and
app oxima ely 1
·10−3
. The d i o 15 measu emen s (co esponds o 15
minu es) is somewha la ge and o he same o de o magni ude as he
expec ed epea abili y.
In Figu e 13 he cable s abili y is shown a e pe o ming he es p o-
h ps://doi.o g/10.7795/530.20190805 18 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
75 80 85 90 95 100 105 110
0
0.5
1
1.5
2·10−3
F equency / GHz
||Γn|−|Γall,mean||
1; 2; 3; 4
(a)
Di e ence be ween e lec ion coe icien magni udes and hei mean alue, wi h ou lie s.
75 80 85 90 95 100 105 110
0
0.5
1
1.5
2·10−3
F equency / GHz
||Γn|−|Γall,mean||
1; 2; 3; 4
(b)
Di e ences be ween e lec ion coe icien magni udes and hei mean alue, wi hou
ou lie s.
Fig. 11.
Re lec ion measu emen s o a s able DUT no malised o he mean o n=4
measu emen s: (a) po 1 and (b) po 2.
75 80 85 90 95 100 105 110
0.5
1
1.5
2
·10−3
F equency / GHz
S abili y
d i n=4; d i n=15; d i end n=4
Fig. 12.
S abili y e alua ion (d i ) wi h n=15 measu emen s, one measu emen
each minu e.
cedu e gi en in [23]. This consis s o epea ed mo emen s and e lec ion
measu emen s o a cable (he e se e al cables including equency ex ende )
e mina ed wi h a ma ched load and a sho -ci cui and calcula ing he
maximum di e ences, aking bo h magni ude and phase in o accoun .
h ps://doi.o g/10.7795/530.20190805 19 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
75 80 85 90 95 100 105 110
1
1.5
2
2.5
·10−2
F equency / GHz
T ansmission s abili y / dB
10 cm mo emen ; 25 cm mo emen
(a) T ansmission s abili y in dB (cg-12)
75 80 85 90 95 100 105 110
0.1
0.15
0.2
F equency / GHz
T ansmission s abili y / °
10 cm mo emen ; 25 cm mo emen
(b) T ansmission s abili y in deg (cg-12)
75 80 85 90 95 100 105 110
−90
−85
−80
−75
F equency / GHz
Re lec ion s abili y / dB
10 cm mo emen ; 25 cm mo emen
(c) Re lec ion s abili y in dB (cg-12)
Fig. 13. Cable s abili y [23] o 10 cm and 25 cm cable mo emen s.
In his case, he esul s a e in he o de o magni ude one would expec a
hese equencies and don’ change much o cable mo emen s o 10 cm o
20 cm. This indica es, ha all cables connec ed o he ex ende s a e qui e
s able. I he esul s a e no as good as expec ed, one should es all cables
sepa a ely. Usually his in ol es coaxial measu emen s up o only 20 GHz
o less and ollowing he same p ocedu e.
h ps://doi.o g/10.7795/530.20190805 20 o 25
Rec angula Wa eguide Connec ions a F equencies abo e 100 GHz
3.4.2 Measu emen s o 220 o 330 GHz:
WR3 / WM-864 / R 2.6k / WG 32
The wa eguide band 220 GHz o 330 GHz is suppo ed by he langes desc ibed
in IEEE S d. 1785.2-2016 and he UG-387 lange. Al hough he UG-387
lange can be used a hese equencies, i is no ecommended, unless a
modi ied e sion inco po a ing imp o ed alignmen ea u es is used. The
IEEE S d. 1785.2-2016 lange designs p o ide be e elec ical pe o mance
a hese equencies.
220 230 240 250 260 270 280 290 300 310 320
0
5
10
·10−3
F equency / GHz
S abili y
d i n=4; d i n=15 d i end n=4
Fig. 14. S abili y e alua ion (d i ) wi h n lush sho -ci cui measu emen s.
In Figu e 14 he s abili y based on epea ed measu emen s on a ixed imescale
(one e e y 60 sec.) o a s able DUT (wi hou econnec ing) is e alua ed.
Compa ed o he measu emen s up o 110 GHz, see Figu e 12, he sys em
d i is la ge . In 4 minu es i is app oxima ely
2·10−3
and o 15 minu es i
eaches
10·10−3
a he highes equency. The main eason o his is he lowe
s abili y o he equency ex ende s, hus any epea abili y measu emen s
a e s ongly supe imposed by he ins umen d i .
220 230 240 250 260 270 280 290 300 310 320
0
5
10
·10−3
F equency / GHz
Repea abili y
UG-387 mod. IEEE 1785.2a
Fig. 15. Repea abili y measu emen s [23] o a s able DUT o di e en langes.
In Figu e 15 epea abili y measu emen s a e shown o di e en lange
con igu a ions: s anda d lange o he equency ex ende (modi ied UG-
h ps://doi.o g/10.7795/530.20190805 21 o 25