An analysis of microstrip line structures in which either the strip or the ground plane or both are made of a high Tc superconductor is presented. The effect of implementation of a superconductor to the strip and the ground plane is explained with the calculation of a conductor loss of the structure by the Phenomenological Loss Equivalence Method (PEM). The theoretical values are compared with the experimental results from a ring resonator which is made of a gold ground plane and a high Tc superconductor, YBa2Cu3O(7-x), strip

Bhasin, K. B.

Chorey, E. M.

Itoh, T.

Kong, K.-S.

Lee, H.-Y.

English

NASA Technical Reports Server

NASA Technical Memorandum 103182
Analysis of Microstrip Lines With
Alternative Implementation of
Conductors and Superconductors
K.-S. Kong, H.-Y. Lee, and T. Itoh
The University of Texas at Austin
Austin, Texas
E.M. Chorey
Sverdrup Technology, Inc.
Lewis Research Center Group
Brook Park, Ohio
K.B. Bhasin
Lewis Research Center
Cleveland, Ohio
Prepared for the
1990 Asia-Pacific Microwave Conference
sponsored by the Institute of Electronics, Information
and Communications Engineers
Tokyo, Japan, September 18-21, 1990
( , A-I,-_ IU , ) Y _ i ..... j-, l
L _ C L
NoU-279A_J
n_13_
https://ntrs.nasa.gov/search.jsp?R=19900018650 2020-03-19T21:04:58+00:00Z
W
ANALYSIS OF MICROSTRIP LINES WITH ALTERNATIVE
IMPLEMENTATIONS OF CONDUCTORS AND SUPERCONDUCTORS
K.-S. Kong*, H.-Y. Lee*, C JVl. Choreyt, and K2L Bhasin_
*Department of Electrical and Computer Engineering tSverdrup Technology, Inc., LeRC Group
The University of Texas at Austin, Austin, TX 78712 Brook Park, OH 44142
USA. USA.
eNASA Lewis Research Center
Cleveland, OH 44135
USA.
Abstract
This paper presents analysis of microstrip line structures in which either the strip or
the ground plane or both are made of a high Tc superconductor. The effect of
implementation of a superconductor to the strip and the ground plane is explained with the
calculation of a conductor loss of the structure by the Phenomenological Loss Equivalence
Method(PEM). The theoretical values are compared with the experimental results from a
ring resonator which is made of a gold ground plane and a high Tc superconductor,
YBa2Cu307-x, strip.
Introduction
In this paper, we calculate and compare Q
values of the microstrip line structures in which either
the strip or the ground plane or both are a high Tc
superconductor. The motivation for this study is to
provide the theoretical basis for the effective application
of a superconductor to the microstrip line as well as
other planar transmission lines. The analytical method
in this paper is based on the Phenomenological Loss
Equivalence Method (PEM) [1,2] and the introduction
of the superposition principle of the internal impedances
from the strip and the ground plane of the microstrip
line. By using this method, we calculate the Q value of
the ring resonator which has a superconducting strip
and a normal conducting ground and compare the
results with the experimental data.
Analysis of Various Superconducting
Microstrip Line Structure
We analyze the various superconducting
microstrip line structures that have alternative
implementations of a superconductor and a normal
conductor into the strip or the ground plane as shown in
Fig.l. There are field penetrations even inside of the
superconductor. These field penetrations contribute to
the internal impedance and cause the conductor loss in
the microstrip line structure as shown in Fig.2. The
internal impedances from strip conductor and the
ground plane are seperately calculated by PEM. Then,
the total internal impedance is obtained by using me
superposition of internal impedances. The internal
impedance of each case is obtained by considering the
cases where either strip or the ground plane is perfect.
When the ground plane is assumed to be perfect, the
field penetration occurs only in the strip conductor. In
this ease, the geometric factor, say G1, of the
microstrip line is obtained from the magnetic field
penetration inside of the strip conductor. The
equivalent strip [1,2] is obtained from G1. The internal
impedance of mierostrip line under the assumption of a
perfect ground plane can be obtained as Zil =
G 1"Zs l'coth(Zs 1"¢_I .A.G 1) where Zs 1, o 1 and A are
the surface impedance, the conductivity of the material
and the cross section"(w-t) of the strip, respecive.ly.
Next, we consider the case where the field penetranon
occurs only in the ground plane. In this ease, the
geometric factor, G2, is obtained from the field
penetration in the ground plane. The intemai impedance
from the ground plane is obtained as Zi2. = G2.Zs2.coth
(Zs2.o2-A'G2) where Zs2 and ¢_2 are surface
impedance and conductivity of the ground, respectively.
Then, the total internal impedance is obtained by adding
Zil and Zi2. We calculate the propagation constant of
the microstip line suaacture by adding this internal
impedance to the external impedance and by using the
transmission line model. Since our method is based on
the PEM, this can be applied to any field penetration
depth compared with the conductor thickness as
demonstrated in reference [ 1, 2].
Comparison Between Microstip Lines with
Various Superconductor Implementation
The conductor losses of each microstrip line in
Fig. 1 are calculated by applying the method explained
above. Then, we calculate Q values of each strip line
by additional consideration of substrate loss [3]. This
will give us insight to the effects of an application of
superconductor on microsnip line. The dimensions of
the su'ucture are shown in Fig.3 (a). For the calculation,
we use the measured conductivity values of the
YBa2Cu307-x film obtained from the power
transmitted through the film and a two fluid model [4].
The calculated Q values of each structure at 35 GHz ate
shown and compared in Fig.3. In this calculation, the
value of 5.8 x 10-4 is used for loss tangent. Since the
current is more concentrated on the strip, the
implementation of a superconductor in the strip gives
more influence on the loss as expected. The extent of
an effect of the implementation of a superconductor in
the microsu'ip line can be different for different
geometric sm_ctures of the microstrip line.
Next, we compare our calculated results with
the experimental results from the ring resonator
structure shown in Fig.4. This ring resonator has the
resonant frequency of 35.0 GHz The detailsof the
fabricationof thisstructureand the measurements are
presented elsewhere [5]. The stripof this ring
resonatorisa thinfilmof YBa2Cu307-x depositedon
LaA1203 by a laserablatedtechnique. The ground
planeconsistsof Ti/ Au. A thinTi layerisemployed to
make thedepositionof thegold on thesubsu'ateand its
effecton the structureisnegligiblebecause itis thin
compared with a gold layer. Fig.5 shows the
experimentalQ valuesand thecalculatedQ valueswith
the variationof loss tangent of the substrate.The
calculatedvaluesof Q arc higherthantheexperimental
results.There are severalfactorsfor thisdiscrepancy
between the experimentaland theoreticalresults.The
ring resonatorwas builtwith a YBa2Cu307-x film
differentfrom thefilmon which theconductivityvalues
were measured. The YBa2Cu307-x film used in the
ringresonaltorhas lowerTc and lower qualitythanthe
one used in the conductivitymeasurement. Also,itis
more affectedby the surfaceroughness because itis
patterned.Another factorcan be theedge currenteffect
on the superconductingringresonator.Also,sincethe
conductor loss from the gold and superconductor
decreases at the low temperature region, the substrate
loss becomes more dominent. However, the
information on the loss tangent of the subsn'ate is not
available at low temperature region. As we can observe
in Fig.5, the Q values depend on the value of loss
tangent of the substrate used in the calculation. The
accuratecharacteristicsof the substrateshould be done
inordertomake itmeaningfultocompare thetheoretical
and experimentalresults.
Conclusion
In thispaper,we presenteda theoreticalnalysis
of thesuperconductingmicrostriplineswiththevarious
implementations of a superconductor and a normal
conductor intothe stripor the ground plane of the
microstrip line. By using the method presented, we
calculated the Q values of a ring resonator with the thin
YBa2Cu307.x stripand the gold ground plane. This
theoreticalresultsare compared and discussedwith
experimentalresultsof a ringresonatorwith the thin
YBa2Cu307-x snipand thegold ground plane.Itwas
found thatthesubsu'atelossbecomes very critical at the
superconductingmicrosnipline.
Acknowledgement
The authors at the Universityof Texas were
supported by the cooperative agreement NCC-3154
from NASA and the Texas Advanced Technology
Program. The PEM method was originallydeveloped
under support by grant N00014-g9-J-1006 at The
Universityof Texas atAustin from the U.S. Officeof
Naval Research.
References
IllH.-Y. Lee and T. Itoh,"Phenomenological loss
equivalencemethod forplanarquasi-TEM
transmissionlinewitha thinnormal conductoror
superconductor,"IEEE Trans.Microwave Theory
Tech.,Vol. MTT-37, Number 12,December
1989.
[2] H.-Y. Lee, K.-S.Kong, T. hoh, " Conductor
losscalculationof superconductingmicrosnip
fineusinga phenomenologicallossequivalence
method," 19thEuropean Microwave
Conference,London, England,September
1989.
[3] IC C. Gupta, R. Garg, and I.I.Bahl, "
Microsnip linesand sloflines",Artech House,
Inc.,(1979).
[41
[5]
NASA TechnicalMemorandum, "Millimeter
Wave TransmissionStudies of YBa2Cu307-x
Thin Films in the26.5 to40.0GHz Frequency
Range", tobe publishedinProceedingofThird
Annual Superconductorapplication,1990.
K.B. Bhasin, C.M. Chorey, I.D.Warner,
K.-S. Kong, H.-Y. Lee and T. Itoh,
"Performance and Modeling ofSuperconducting
Ring ResonatorsatMillimeter-Wave
Frequencies",IEEE MTT-S Int.Microwave
Symposium, pp 269-272, May 1990.
/-SUPERCONDUCTOR (STRIP)
/ (YBa2Cu307_ x)
(SUBSTRATE)
GOLD (GROUND PLANE) J
(a) SUPERCONDUCTING STRIP, NORMAL CONDUCTING GROUND.
FGOLD (STRIP)
r_'//////./////////////A
SUPERCONDUCTOR (GROUND) J
(b) SUPERCONDUCTING GROUND, NORMAL CONDUCTING STRIP.
r SUPERCONDUCTOR (STRIP)
-LaAI203
(SUBSTRAIE)
SUPERCONDUCTOR (GROUND) J
(c) SUPERCONDUCTING STRIP, SUPERCONDUCTING GROUND.
FIGURE I. - SUPERCONDUCTING MICROSTRIP LINES.
FIELD PENETRATION
Ri 1 Lil
FIELD PENETRATION -/
Ri2 ki2
FIGURE 2. - FIELD PENETRATION IN THE STRIP AND THE
GROUND PLANE.
b-3° .m-H L__
STRIP-- __ 0.5 pm 2.54 _m
l
1,0 pm
GROUND -/
(a) MICROSTRIP LINE.
[] CASE I: STRIP, GOLD:
GROUND, SUPERCONDUCTOR.
CASE 2: STRIP, SUPERCONDUCTOR;
GROUND, GOLD.
0 CASE 3: STRIP, SUPERCONDUCTOR:
GROUND, SUPERCONDUCTOR.
2000 --
1600 i
1200
Q
800
400 --
I I I I I I
20 30 40 50 60 70 80
TEMPERATURE, K
(b) Q-VALUES OF SUPERCONDUCTING MICROSTRIP LINES.
FIGURE 3. - DIMENSIONS AND Q-VALUES OF SUPERCONDUCTING
STRIP LINES.
LaAI.
RI: 918 _m
R2:1061 _m
W : 143 _m
6 : 36 _m
'
6 6
<a) TOP VIEW OF THE RING RESONATOR.
tl: 0.5 pm
ts: 254 IJm
tt: 0.1 pm
tg: 1.0 _m
YBa2Cu307-x 7
|g--_ Au J
tt: (TITANIUM LAYER)
(b) SIDE VIEW OF THE RING RESONATOR.
FIGORE q. - SUPERCONDUCTING RING RESONATOR.
tt
2qoo r--
/Q [] EXPERIMENT
2000 _--- %,, <> I: tan 6 = 5.8E-4
| L_ 0 2: tan 6 = 8.3E-5
1600 _---_ 1,2: THEORETICAL
1200
8OO
qoo
o I I I I T-_P I
20 30 40 50 60 70 80 90
TEMPERATURE,K
FIGURE S, - EXPERIMENTAL AND THEORETICAL VALUES
OF Q IN SUPERCONDUCTING RING RESONATOR,
4
National Aeronautics and
Space Administration
1. Report No.
NASA TM-103182
4. Title and Subtitle
Analysis of Microstrip Lines With Alternative
Implementations of Conductors and Superconductors
7. Author(s)
K.-S. Kong, H.-Y. Lee, T. Itoh,
C.M. Chorey, and K.B. Bhasin
9. Performing Organization Name and Address
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191
12. Sponsoring Agency Name and Address
National Aeronautics and Space Administration
Washington, D.C. 20546-0001
Report Documentation Page
2, Government Accession No. 3. Recipient's Catalog No.
5. Report Date
6. Performing Organization Code
8. Performing Organization Report No.
E-5562
10. Work Unit No.
506-44-20
11. Contract or Grant No.
13. Type of Report and Period Covered
Technical Memorandum
14. Sponsoring Agency Code
15. Supplementary Notes
Prepared for the 1990 Asia-Pacific Microwave Conference sponsored by the Institute of Electronics, Information and Commercialization
Engineers, Tokyo, Japan, September 18-21, 1990. K.-S. Kong, H.-Y. Lee, and T. ltoh, Dept. of Electrical and Computer
Engineering, The University of Texas at Austin, Austin, Texas 78712. C.M. Chorey, Sverdrup Technology, Inc., Lewis Research
Center Group, 2001 Aerospace Parkway, Brook Park, Ohio 44142. K.B. Bhasin, NASA Lewis Research Center.
16. Abstract
This paper presents analysis of microstrip line structures in which either the strip or the ground plane or both are
made of a high Tc superconductor. The effect of implementation of a superconductor to the strip and the ground
plane is explained with the calculation of a conductor loss of the structure by the Phenomenological Loss
Equivalence Method (PEM). The theoretical values are compared with the experimental results from a ring
resonator which is made of a gold ground plane and a high Tc superconductor, YBa2Cu307_ x, strip.
17. Key Words (Suggested by Author(s))
High temperature superconductors
Ring resonator
Microstrip lines
18. Distribution Statement
Unclassified- Unlimited
Subject Category 33
19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of pages
Unclassified Unclassified 6
i
NASA FORM 1626 OCT 86
*For sale by the National Technical Information Service, Springfield, Virginia 22161
22. Price*
A02


National Aeronautics and
Space Administration
Lewis Research Center
Cleveland, Ohio 44135
Office! Business
Penalty for Private Use $300
FOURTH CLASS MAIL
ADDRESS CORRECTION REQUESTED
I!Iil
Postage and Fees Pa_d
Nalronal Aeronautics and
Space AdmlnJstr ahon
N A.C;A 451
!
i
J
t


Analysis of Microstrip Lines with Alternative Implementation of Conductors and Superconductors

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server