Superconductivity - Part 16: Electronic characteristic measurements - Power-dependent surface resistance of superconductors at microwave frequencies

This part of IEC 61788 involves describing the standard measurement method of power-dependent surface resistance of superconductors at microwave frequencies by the sapphire resonator method. The measuring item is the power dependence of Rs at the resonant frequency. The following is the applicable measuring range of surface resistances for this method:
Frequency: f ~ 10 GHz
Input microwave power: Pin < 37 dBm (5 W)
The aim is to report the surface resistance data at the measured frequency and that scaled to 10 GHz using the Rs   f2 relation for comparison.

Supraleitfähigkeit - Teil 16: Messung der elektronischen Eigenschaften - Leistungsabhängiger Oberflächenwiderstand bei Mikrowellenfrequenzen

Supraconductivité - Partie 16: Mesures de caractéristiques électroniques - Résistance de surface des supraconducteurs aux hyperfréquences en fonction de la puissance

La CEI 61788-16:2013 décrit la méthode de mesure normale de la résistance de surface des supraconducteurs aux hyperfréquences en fonction de la puissance par la méthode du résonateur au saphir. La grandeur de mesure est la dépendance en fonction de la puissance de Rs à la fréquence de résonance. Cette méthode est applicable à des fréquences de l'ordre de 10 GHz pour une puissance d'entrée inférieure à 37 dBm (5 W). Il s'agit de consigner dans un rapport les données de résistance de surface à la fréquence mesurée et celles qui sont ramenées à une échelle de 10 GHz. Mot clé: supraconductivité

Superprevodnost - 16. del: Meritve elektronskih karakteristik - Površinska upornost superprevodnikov, odvisna od moči, pri mikrovalovnih frekvencah

Ta del IEC 61788 vključuje opis standardne merilne metode od napajanja odvisne površinske upornosti superprevodnikov pri mikrovalovnih frekvencah po metodi safirskega resonatorja. Predmet meritve je odvisnost napajanja Rs pri resonančni frekvenci. Spodaj je naveden ustrezen merilni obseg površinskih upornosti za to metodo:
Frekvenca: f ~ 10 GHz
Vhodna mikrovalovna moč: Pin < 37 dBm (5 W)
Namen je sporočiti podatke o površinski upornosti pri izmerjeni frekvenci, prilagojeni do 10 GHz, s pomočjo primerjalnega razmerja Rs   f2.

General Information

Status
Published
Publication Date
19-May-2013
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
06-May-2013
Due Date
11-Jul-2013
Completion Date
20-May-2013

Buy Standard

Standard
SIST EN 61788-16:2013
English language
33 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.RYUãLQVNDNYHQFDKSupraleitfähigkeit - Teil 16: Messung der elektronischen Eigenschaften - Leistungsabhängiger Oberflächenwiderstand bei MikrowellenfrequenzenSupraconductivité - Partie 16: Mesures de caractéristiques électroniques - Résistance de surface des supraconducteurs aux hyperfréquences en fonction de la puissanceSuperconductivity - Part 16: Electronic characteristic measurements - Power-dependent surface resistance of superconductors at microwave frequencies29.050Superprevodnost in prevodni materialiSuperconductivity and conducting materials17.220.20Measurement of electrical and magnetic quantitiesICS:Ta slovenski standard je istoveten z:EN 61788-16:2013SIST EN 61788-16:2013en01-julij-2013SIST EN 61788-16:2013SLOVENSKI

STANDARD
SIST EN 61788-16:2013
EUROPEAN STANDARD EN 61788-16 NORME EUROPÉENNE
EUROPÄISCHE NORM April 2013

CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2013 CENELEC -

All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61788-16:2013 E
ICS 17.220.20; 29.050
English version
Superconductivity -
Part 16: Electronic characteristic measurements -

Power-dependent surface resistance of superconductors at microwave frequencies (IEC 61788-16:2013)

Supraconductivité -
Partie 16: Mesures de caractéristiques électroniques -

Résistance de surface des supraconducteurs aux hyperfréquences en fonction de la puissance (CEI 61788-16:2013)

Supraleitfähigkeit -
Teil 16: Messung der elektronischen Eigenschaften -

Leistungsabhängiger Oberflächenwiderstand bei Mikrowellenfrequenzen (IEC 61788-16:2013)

This European Standard was approved by CENELEC on 2013-02-20. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

SIST EN 61788-16:2013
EN 61788-16:2013 - 2 -

Foreword The text of document 90/309/FDIS, future edition 1 of IEC 61788-16, prepared by IEC TC 90, "Superconductivity" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 61788-16:2013.

The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2013-11-20 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2016-02-20

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 61788-16:2013 was approved by CENELEC as a European Standard without any modification. SIST EN 61788-16:2013

- 3 - EN 61788-16:2013
Annex ZA
(normative)

Normative references to international publications with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

NOTE

When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.

Publication Year Title EN/HD Year
IEC 60050 Series International electrotechnical vocabulary
- -
IEC 61788-15 - Superconductivity -

Part 15: Electronic characteristic measurements - Intrinsic surface impedance of superconductor films at microwave frequencies EN 61788-15 -

SIST EN 61788-16:2013
SIST EN 61788-16:2013

IEC 61788-16 Edition 1.0 2013-01 INTERNATIONAL STANDARD NORME INTERNATIONALE Superconductivity –

Part 16: Electronic characteristic measurements – Power-dependent surface resistance of superconductors at microwave frequencies

Supraconductivité –

Partie 16: Mesures de caractéristiques électroniques – Résistance de surface des supraconducteurs aux hyperfréquences en fonction de la puissance

INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE V ICS 17.220.20; 29.050 PRICE CODE CODE PRIX ISBN 978-2-83220-582-2

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé. SIST EN 61788-16:2013 colourinside

– 2 – 61788-16 © IEC:2013

CONTENTS FOREWORD ........................................................................................................................... 4 INTRODUCTION ..................................................................................................................... 6 1 Scope ............................................................................................................................... 7 2 Normative references ....................................................................................................... 7 3 Terms and definitions ....................................................................................................... 7 4 Requirements ................................................................................................................... 8 5 Apparatus ......................................................................................................................... 8 5.1 Measurement system .............................................................................................. 8 5.1.1 Measurement system for the tan δ of the sapphire rod ................................. 8 5.1.2 Measurement system for the power dependence of the surface resistance of superconductors at microwave frequencies ............................. 9 5.2 Measurement apparatus ........................................................................................ 10 5.2.1 Sapphire resonator .................................................................................... 10 5.2.2 Sapphire rod .............................................................................................. 10 5.2.3 Superconductor films ................................................................................. 11 6 Measurement procedure ................................................................................................. 11 6.1 Set-up ................................................................................................................... 11 6.2 Measurement of the tan δ of the sapphire rod ........................................................ 11 6.2.1 General ..................................................................................................... 11 6.2.2 Measurement of the frequency response of the TE021 mode ..................... 11 6.2.3 Measurement of the frequency response of the TE012 mode ..................... 13 6.2.4 Determination of tan δ of the sapphire rod ................................................. 13 6.3 Power dependence measurement .......................................................................... 14 6.3.1 General ..................................................................................................... 14 6.3.2 Calibration of the incident microwave power to the resonator..................... 15 6.3.3 Measurement of the reference level ........................................................... 15 6.3.4 Surface resistance measurement as a function of the incident microwave power ....................................................................................... 15 6.3.5 Determination of the maximum surface magnetic flux density .................... 15 7 Uncertainty of the test method ........................................................................................ 16 7.1 Surface resistance................................................................................................. 16 7.2 Temperature .......................................................................................................... 17 7.3 Specimen and holder support structure ................................................................. 18 7.4 Specimen protection .............................................................................................. 18 8 Test report ...................................................................................................................... 18 8.1 Identification of the test specimen ......................................................................... 18 8.2 Report of power dependence of Rs values............................................................. 18 8.3 Report of test conditions ........................................................................................ 18 Annex A (informative)

Additional information relating to Clauses 1 to 7 ............................... 19 Annex B (informative)

Uncertainty considerations ............................................................... 24 Bibliography .......................................................................................................................... 29

Figure 1 – Measurement system for tan δ of the sapphire rod ................................................. 9 Figure 2 – Measurement system for the microwave power dependence of the surface resistance ............................................................................................................................... 9 SIST EN 61788-16:2013

61788-16 © IEC:2013 – 3 –

Figure 3 – Sapphire resonator (open type) to measure the surface resistance of superconductor films ............................................................................................................. 10 Figure 4 – Reflection scattering parameters (|S11| and |S22|) ............................................... 13 Figure 5 – Term definitions in Table 3 ................................................................................... 17 Figure A.1 – Three types of sapphire rod resonators ............................................................. 19 Figure A.2 – Mode chart for a sapphire resonator (see IEC 61788-15) .................................. 20 Figure A.3 – Loaded quality factor QL measurements using the conventional 3 dB method and the circle fit method ........................................................................................... 21 Figure A.4 – Temperature dependence of tan δ of a sapphire rod measured using the two-resonance mode dielectric resonator method [3] ............................................................ 22 Figure A.5 – Dependence of the surface resistance Rs on the maximum surface magnetic flux density Bs max [3] .......................................................................................................... 23

Table 1 – Typical dimensions of the sapphire rod .................................................................. 11 Table 2 – Specifications of the vector network analyzer ........................................................ 16 Table 3 – Specifications of the sapphire rods ........................................................................ 17 Table B.1 – Output signals from two nominally identical extensometers ................................ 25 Table B.2 – Mean values of two output signals ..................................................................... 25 Table B.3 – Experimental standard deviations of two output signals ...................................... 25 Table B.4 – Standard uncertainties of two output signals ...................................................... 26 Table B.5 – Coefficient of Variations of two output signals .................................................... 26

SIST EN 61788-16:2013
– 4 – 61788-16 © IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
SUPERCONDUCTIVITY –
Part 16: Electronic characteristic measurements –
Power-dependent surface resistance
of superconductors at microwave frequencies

FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61788-16 has been prepared by IEC technical committee 90: Superconductivity. The text of this standard is based on the following documents: FDIS Report on voting 90/309/FDIS 90/318/RVD

Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all the parts in the IEC 61788 series, published under the general title Superconductivity, can be found on the IEC website. SIST EN 61788-16:2013

61788-16 © IEC:2013 – 5 –

The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be

• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer.

SIST EN 61788-16:2013
– 6 – 61788-16 © IEC:2013

INTRODUCTION Since the discovery of high-Tc superconductors (HTS), extensive researches have been performed worldwide for electronic applications and large-scale applications. In the fields of electronics, especially in telecommunications, microwave passive devices such as filters using HTS are being developed and testing is underway on sites [1,2,3,4]1. Superconductor materials for microwave resonators, filters, antennas and delay lines have the advantage of ultra-low loss characteristics. Knowledge of this parameter is vital for the development of new materials on the supplier side and the design of superconductor microwave components on the customer side. The parameters of superconductor materials needed to design microwave components are the surface resistance Rs and the temperature dependence of the Rs. Recent advances in HTS thin films with Rs, several orders of magnitude lower than normal metals has increased the need for a reliable characterization technique to measure this property [5,6]. Among several methods to measure the Rs of superconductor materials at microwave frequencies, the dielectric resonator method [7,8,9] has been useful due to that the method enables to measure the Rs nondestructively and accurately. In particular, the sapphire resonator is an excellent tool for measuring the Rs of HTS materials [10]. In 2002, the International Electrotechnical Commission (IEC) published the dielectric resonator method as a measurement standard [11]. The test method given in this standard enables measurement of the power-dependent surface resistance of superconductors at microwave frequencies. For high power microwave device applications such as those of transmitting devices, not only the temperature dependence of Rs but also the power dependence of Rs is needed to design the microwave components. Based on the measured power dependence, the RF current density dependence of the surface resistance can be evaluated. The simulation software to design the device gives the RF current distribution in the device. The results of the power dependence measurement can be directly compared with the simulation and allow the power handling capability of the device to be evaluated.

The test method given in this standard can be also applied to other superconductor bulk plates including low-Tc material. This standard is intended to give an appropriate and agreeable technical base for the time being to those engineers working in the fields of electronics and superconductivity technology. The test method covered in this standard is based on the VAMAS (Versailles Project on Advanced Materials and Standards) pre-standardization work on the thin film properties of superconductors.

___________ 1
Numbers in square brackets refer to the Bibliography. SIST EN 61788-16:2013
61788-16 © IEC:2013 – 7 –
SUPERCONDUCTIVITY –
Part 16: Electronic characteristic measurements –
Power-dependent surface resistance
of superconductors at microwave frequencies

1 Scope This part of IEC 61788 involves describing the standard measurement method of power-dependent surface resistance of superconductors at microwave frequencies by the sapphire resonator method. The measuring item is the power dependence of Rs at the resonant frequency.

The following is the applicable measuring range of surface resistances for this method: Frequency: f ~ 10 GHz Input microwave power: Pin < 37 dBm (5 W) The aim is to report the surface resistance data at the measured frequency and that scaled to 10 GHz using the Rs ∝ f2 relation for comparison. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050 (all parts), International Electrotechnical Vocabulary (available at: ) IEC 61788-15, Superconductivity – Part 15: Electronic characteristic measurements – Intrinsic surface impedance of superconductor films at microwave frequencies 3 Terms and definitions For the purposes of this document, the definitions given in IEC 60050-815, one of which is repeated here for convenience, apply. 3.1

surface impedance impedance of a material for a high frequency electromagnetic wave which is constrained to the surface of the material in the case of metals and superconductors Note 1 to entry: The surface impedance governs the thermal losses of superconducting RF cavities. Note 2 to entry: In general, surface impedance Zs for conductors including superconductors is defined as the ratio of the electric field Et to the magnetic field Ht, tangential to a conductor surface: Zs = Et /Ht = Rs + jXs, where Rs is the surface resistance and Xs is the surface reactance. SIST EN 61788-16:2013

– 8 – 61788-16 © IEC:2013

4 Requirements The surface resistance Rs of a superconductor film shall be measured by applying a microwave signal to a sapphire resonator with the superconductor film specimen and then measuring the insertion attenuation of the resonator at each frequency. The frequency shall be swept around the resonant frequency as the center and the insertion attenuation - frequency characteristics shall be recorded to obtain the Q-value, which corresponds to the loss.

The target relative combined standard uncertainty of this method is the coefficient of variation (standard deviation divided by the average of the surface resistance determinations), which is less than 20 % for a measurement temperature range from 30 K to 80 K. It is the responsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Hazards exist in such measurement. The use of a cryogenic system is essential to cool the superconductors and allow transition into the superconducting state. Direct contact of skin with cold apparatus components can cause immediate freezing, as can direct contact with a spilled cryogen. The use of an RF-generator is also essential to measure the high-frequency properties of materials. If its power is excessive, direct contact to human bodies could cause immediate burns. 5 Apparatus

5.1 Measurement system 5.1.1 Measurement system for the tan δ of the sapphire rod Figure 1 shows a schematic diagram of the system required for the tan δ measurement. The system consists of a network analyzer system for transmission measurements, a measurement apparatus in which a sapphire resonator with superconductor films is fixed, and a thermometer for monitoring the measuring temperature.

The incident power generated from a suitable microwave source such as a synthesized sweeper is applied to the sapphire resonator fixed in the measurement apparatus. The transmission characteristics are shown on the display of the network analyzer. The measurement apparatus is fixed in a temperature-controlled cryocooler. To measure the tan δ of the sapphire rod, a vector network analyzer is recommended, since its measurement accuracy is superior to a scalar network analyzer due to its wide dynamic range.

SIST EN 61788-16:2013
61788-16 © IEC:2013 – 9 –

Cryocooler Thermal sensor Measurement apparatus Vector network analyzer Thermometer Synthesized sweeper S-parameter test set System interface IEC

003/13

Figure 1 – Measurement system for tan δ of the sapphire rod 5.1.2 Measurement system for the power dependence of the surface resistance of superconductors at microwave frequencies Figure 2 shows the measurement system for the power dependence of the surface resistance of superconductors using a sapphire resonator. A travelling wave tube (TWT) power amplifier with a maximum output power of around 40 dBm is inserted at the input into the resonator. The maximum input power into the resonator is around 37 dBm in this measurement system shown in Figure 2. The typical maximum input power of a network analyzer is in the order of 0 dBm, so a measurement circuit shall be designed to avoid direct exposure of high powered microwaves to the network analyzer, and also by using a circulator and an attenuator, significant reflection from the sapphire resonator should not affect the TWT amplifier.

Synthesized sweeper Power sweep TWT amplifier Circulator Coupler Attenuator Power meter Cryostat Resonator Coupler Circulator Vector network analyzer IEC

004/13

Figure 2 – Measurement system for the microwave power dependence of the surface resistance SIST EN 61788-16:2013

– 10 – 61788-16 © IEC:2013

Incident microwave power to the resonator is calibrated using a power meter before the measurement (dotted line in Figure 2). The incident power of the microwave is swept by changing the input power of the TWT amplifier. 5.2 Measurement apparatus 5.2.1 Sapphire resonator Figure 3 shows a schematic diagram of a typical sapphire resonator (open type resonator) used to measure Rs of superconductor films and tan δ of the sapphire rod [9]. In the sapphire resonator, a sapphire rod was sandwiched between two superconducting films. The upper superconductor film is pressed down by a spring, which is made of phosphor bronze. The use of a plate type spring is recommended to improve measurement accuracy. This type of spring reduces the friction between the spring and the rest of the apparatus, and facilitates the movement of superconductor films during the thermal expansion of the sapphire rod. Two semi-rigid cables for measuring transmission characteristics of the resonator shall be attached on both sides of the resonator in axially symmetrical positions (φ = 0 and π, where φ is the rotational angle around the central axis of the sapphire rod). A semi-rigid cable with an outer diameter of 3,50 mm is recommended. Each of the two semi-rigid cables shall have a small loop at the end. The plane of the loop shall be set parallel to that of the superconductor films in order to suppress the unwanted TMmn0 modes. The coupling loops shall be carefully checked for cracks in the spot weld joint that may have developed upon repeated thermal cycling. These cables can move right and left to adjust the insertion attenuation (IA). In this adjustment, coupling of unwanted modes to the interested resonance mode shall be suppressed. Unwanted coupling to the other modes reduces the high Q value of the TE mode resonator. To suppress the unwanted coupling, special attention shall be paid to designing high Q resonators. Two other types of resonators usable along with the open type shown in Figure 3 are explained in A.1. A reference line made of a semi-rigid cable shall be used to measure the full transmission power level, i.e. the reference level. The cable length equals to the sum of the two cables of the measurement apparatus. To minimize the measurement error, two superconductor films shall be set in parallel. To ensure that the two superconductor films remain in tight contact with the ends of the sapphire rod, without any air gap, the surface of the two films and both ends of the rod shall be cleaned carefully.

Superconductor films Sapphire rod Spring Copper base Loop antenna IEC
005/13

Figure 3 – Sapphire resonator (open type) to measure the surface resistance of superconductor films 5.2.2 Sapphire rod A high-quality sapphire rod with low tan δ is required to achieve the requisite measurement accuracy on Rs. A recommended sapphire rod is expected to have a tan δ less than 10–6 at 77 K. To minimize the measurement error in Rs of the superconductor films, both ends of the sapphire rods shall be polished parallel to each other and perpendicular to the axis. Specifications of the sapphire rods are described in 7.1. SIST EN 61788-16:2013

61788-16 © IEC:2013 – 11 –

The diameter and height of the sapphire rod shall be carefully designed to ensure the TE011, TE021 and TE012 modes do not couple to other TM, HE and EH modes, since coupling between TE mode and other modes causes the unloaded Q to deteriorate. The design guideline for the sapphire rod is described in A.2. Table 1 shows typical dimensions of the sapphire rod for a TE011–mode resonant frequency of about 10 GH

...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.