COMMISSION A: Electromagnetic Metrology(November 2013 – October 2016)
Edited by
Mitsuru Musha (University of Electro-communications) and
Masatoshi Kajita (National Institute of Information and Communications Technology)
A1. Time and Frequency Standards and Time Transfer Technique
The researches and developments on time and frequency standards and time transfer in Japanare mainly carried out in National Metrology Institute of Japan (NMIJ) and National Institute ofInformation Technology (NICT)In NMIJ, the second cesium fountain, NMIJ-F2, for primary frequency standards has beendeveloped. The frequency stability reaches 8.3×10-14τ-1/2 (τ: averaging time) using an
ultra-stable local oscillator and high atom number [Takamizawa et al., 2014]. The local
oscillator is a cryogenic sapphire oscillator using an ultra-low-vibration pulse-tube cryocooler
and cryostat. The high atom number is achieved by high power of the cooling laser beams andoptical pumping to the Zeeman sublevel mF = 0. In addition, the type B uncertainty has been
evaluated to be 7×10-16 without the inclusion of uncertainty by the minor effects [Takamizawa etal., 2015a]. Moreover, NMIJ-F2 was used for absolute frequency measurement of our Sr opticallattice clock as a transfer oscillator [Tanabe et al., 2015]. Besides, external cavity diode lasers
with low frequency drift have been developed for long-term operation of the fountain[Takamizawa et al., 2015b, Takamizawa et al., 2016].
Ultrastable microwave oscillators: Two liquid-helium-cooled cryogenic sapphire-resonator
oscillators (CSOs), have been modified to operate using cryo-refrigerators and low-vibration
cryostats [Ikegami et al., 2016]. The Allan deviation of the first cryo-refrigerator-cooled CSO(cryoCSO) was evaluated to be better than 2×10-15 for averaging times of 1 s to 30 000 s, which
is better than that of the original liquid helium cooled CSO. It is now used with our Cs atomic
fountainfrequency

standard,

NMIJ-F2,

which

has

achievednearlyquantum-projection-noise-limited frequency stability. The Allan deviation of the second
cryoCSO is better than 4×10-15 from 1 s to 6 000 s averaging time.
At present four active hydrogen maser frequency standards and three cesium atomic clocks
with high-performance beam tubes (Agilent 5071A) are operated at NMIJ for time keeping.
Those atomic clocks are kept in individual chambers, whose temperatures are kept to within 0.2
deg C. One of the hydrogen masers is used as a source oscillator for the generation of UTC(NMIJ) to improve the short-term stability. UTC (NMIJ) is created by frequency-steering thehydrogen maser output signal to UTC using a frequency stepper.
In NMIJ, Dual frequency carrier phase GPS receiver is one of the main international time and1frequency transfer tools. NMIJ has the Two Way Satellite Time and Frequency Transfer(TWSTFT) facilities for Asia Pacific link and for Asia-European link.
Frequency Calibration Service at NMIJ; NMIJ has been providing the remote frequency
calibration service using the GPS common-view method and Internet since 2006. The CMCs of
the service are 1.1×10-13 (baseline: 50 km), 1.4×10-13 (baseline: 500 km) and 4.9×10-13 (baseline:
1,600 km) at an averaging time of one day. The number of users is 20 in 2016; it is on the riseyear by year.
NICT and TL have evaluated a software-defined receiver (SDR) comprising a high-resolution
correlator and successive interference cancellation associated with open-loop configuration inorder to improve the stability of operational two-way satellite time and frequency transfer(TWSTFT) [Huang et al, 2016]. According to the result of the measurements TWSTFT receiver
reduces the time deviation from 140 ps to 73 ps at averaging time of 1 h, and occasionallysuppresses diurnals. NICT developed a state-of-art system for the remote frequency comparisonof optical clocks without a flywheel oscillator at the remote end. The system uncertainty andinstability to be at the low 10−15 level using an Sr lattice clock [Fujieda et al., 2016].
Fundamental research of chip scale atomic clock (CSAC) has been performed in Tokyo
Metropolitan University (TMU) and NICT. In TMU, Ramsey spectrum was observed using
pulsed laser, with which high frequency stability is obtained with lower electric power [Yano etal., 2014] [Yano et al., 2015]. In NICT, development of chip scale atomic clock (CSAC) started.
The possibility to improve the frequency stability by using the phase modulation is being
searched.
Broadband VLBI system GALA-V has been developed by NICT [Sekido et al., 2016]. The
GALA-V is aimed to make long distance frequency comparison between small diameter
antennas via broadband VLBI observation. A series of test experiments between NICT and
NMIJ have been conducted in 2016. About one pico second delay precision group delay
measurement has been achieved with small diameter antenna pair. It is getting clear that total
observation error is dominated by atmospheric uncertainty [Kondo et al., 2016].
A2. Laser Stabilization & Frequency Measurement
The researches and developments on laser stabilization and frequency measurement in Japan,
especially, the accuracy improvement of 87Sr lattice clock (1S0-3P0 transition), are mainly carriedout NICT, NMIJ and RIKEN - University of Tokyo group.
At NICT, the uncertainty of the absolute frequency of 87Sr lattice clock has been reduced to
9.3 x 10-16 and its systematic uncertainty has been deuced down to 8.6 x 10-17. The directcomparison with Sr lattice clock in Physicarische Technische Bundesanstalt (PTB, Germany)has been performed, and the difference was measured to be (1.1±1,6)ｘ 10-15 [Hachisu, 2014]2

[Hachisu, 2015]. In NICT, a new method to use the Sr lattice clock to calibrate UTC-NICT wasdeveloped. Measurement of three hours every one or two weeks was continued for five months,
and the discrepancy from the SI time scale was maintained to be less than 2 ns [Ido, 2016] .
At NMIJ, the uncertainty of the absolute frequency of the 87Sr lattice clock (1S0-3P0 transition)
has been measured to be 3.7 x 10-15 in 2014 [Akamatsu, 2014]. The uncertainty of the absolute
frequency measurement was mainly limited by that of the comparison with the NMIJ
coordinated universal time (UTC(NMIJ)). To reduce the uncertainty, a Cs atomic fountain clock
was used as a local oscillator to monitor the frequency variation of UTC(NMIJ) during themeasurements in 2015 [Tanabe, 2015]. Consequently, the uncertainty was reduced to 1.2 x 10-15.
The frequency ratio of the clock transitions in Sr and Yb was measured by an optical direct
frequency link between two independent optical lattice clocks of Sr and Yb in 2014. The
fractional uncertainty of the measurement was 1.4 x 10-15 [Akamatsu, 2014a] [Akamatsu,
2014b]. A dual optical lattice clock has been being developing at NMIJ since 2009.
Katori group at the University of Tokyo and RIKEN has been developing optical latticeclocks with strontium (Sr), ytterbium (Yb) and mercury (Hg) atoms. They have also developed
an optical frequency transfer system using a fiber link between the two sites to demonstrate
remote frequency comparison at the level of 10-18 uncertainties.
In 2015, RIKEN group developed two cryogenic Sr optical lattice clocks. Thus far, theaccuracy of Sr optical lattice clocks has been limited by the uncertainty of ambient blackbody
radiation shift. By installing a cryogenic chamber, they have succeeded in reducing theuncertainties of blackbody radiation shifts to 9x10-19 and compared two cryogenic Sr latticeclocks with the uncertainties of 5x10-18 [Ushijima et al., 2015]. RIKEN group has also
developed optical lattice clocks with Hg atoms. Hg atoms have one order of magnitude smaller
sensitivity to the blackbody radiation than Sr and Yb atoms. This allows realizing theuncertainties of 10-18 even in a room-temperature environment. They compared the frequencies
between Hg and Sr optical lattice clocks using a phase-stabilized optical frequency comb anddetermined the frequency ratio with the uncertainties of 8.4x10-17 [Yamanaka et al., 2015].
As a physical property of Yb atoms is similar to that of Sr, Sr optical lattice clocks can sharethe setup with Yb clocks. RIKEN group has modified one of the cryogenic Sr optical latticeclocks to be compatible with Yb optical lattice clocks. They have performed frequency
comparison between Sr and Yb optical lattice clocks and determined the frequency ratio with
4.6x10-17 uncertainties, which is the best accuracy obtained so far between two different atomic
species [Nemitz et al., 2016].
Frequency comparison between two remote Sr optical lattice clocks operated in the
University of Tokyo and RIKEN was performed via a phase-stabilized optical fiber link with
their direct distance of 15 km. The frequency comparison of the remote clocks measures the3relative frequency difference to be 1,653.3(7.5)x10-18, which corresponds to the gravitational red
shift due to the height difference of 1,516(5) cm. The result agrees well with the altitudedifference measured by conventional spirit leveling performed by Geospatial Information
Authority of Japan. The centimeter-level remote clocks’ comparison will become a building
block of future clock network for relativistic geodesy and fundamental science [Takano et al.,2016].
In NICT, a new frequency standard based on the In+ 1S0-3P0 transition frequency is underdevelopment, and the result was close to the measurement obtained by the Erlangen group. The
uncertainty of the order of 10-15 is going to be attained.
The attainable accuracies of vibrational transition frequencies of homonuclear diatomic
molecular ions were theoretically estimated [Kajita et al., 2014]. For the pure vibrationaltransition frequencies of N2+ (with zero nuclear) [Kajita, 2015].
The apparatus for the precise measurement of THz-wave has been developed in NICT
[Nagano et al., 2013] [Ito et.al., 2013].
Hong group at Yokohama National University is developing optical frequency combs andfrequency stabilized lasers.
stability at the 10-12

They have developed a compact iodine-stabilized laser withlevel using a coin-sized laser module [Kobayashi et al. 2015]. This laser has

been recommended by the International Committee for Weights and Measures (CIPM) as an
optical frequency standard at 531 nm.

The compact laser has been applied to long gauge blockmeasurements [Bitou, 2016].
Sugiyama group at Kyoto University has been developing Yb+ and Ba+ ion clocks. The groupaims at search for a temporal variation of the fine-structure constant. They succeeded insingle-ion spectroscopy of the 2S1/2－2D3/2 transition at 435 nm in 171Yb with a spectral width of
380 Hz [Imai et al., 2016]. They observed resolved motional sidebands in the spectra of the 2S1/2－2D5/2 transition at 1.76 µm in single 138Ba+. They succeeded in laser cooling of single 137Ba+
ions which have a clock transition of a low sensitivity to electric quadrupole field [Fujisaki et al.,2016]. They are developing optical frequency-ratio measurement system using octave-spanning
optical frequency combs based on mode-locked titanium-doped sapphire lasers andytterbium-doped potassium-yttrium-tungstate (Yb:KYW) lasers [Mitaki et al., 2014].
Nakagawa group at University of Electro-communications (UEC) has developed an opticalfrequency synthesizer for the precision spectroscopy of highly excited Rydberg states of Rb
atoms. This synthesizer can generate widely tunable 480 nm laser light with an optical power of
150 mW and an absolute frequency uncertainty of less than 100 kHz using a high repetition rate
(325 MHz) Er fiber-based optical frequency comb and a tunable frequency-doubled diode laser
at 960 nm. We demonstrate the precision two-photon spectroscopy of Rydberg states of 87Rb
atoms by observing electromagnetically induced transparency on a vapor cell, and measure the4absolute transition frequencies of 87Rb to nD and nS Rydberg states with an uncertainty of lessthan 130 kHz [Watanabe, 2016]. The measured transition frequencies of Rydberg excitation of
Rb are useful for the recent applications in quantum information processing, quantum
simulations using Rydberg atoms.
Musha group at UEC has developed the optical frequency comb which is based on Er-doped
fiber mode-lock laser for wideband frequency reference and dual comb spectroscopy, theprecision remote dissemination of the reference signal through the long optical fibers andspace-borne frequency stabilized lasers.

For the Japanese space gravitational wave detector

named DECIGO, we have developed the stable and high-power Yb-doped fiber lasers whose
frequency is stabilized in reference to the saturated absorption of iodine at 515 nm to obtainshort- and long term frequency stability, and the intensity noise is also stabilized to dI/I=2x10-8/√Hz at the observation band of DECIGO around 1 Hz. The compact and robust two breadboard
models are now under development for the future space borne stable lasers [Suemasa, 2016].
A3. Realization of Electrical Unit (DC & LF)
Research works and developments on dc and low frequency electrical standards are
implemented in the electrical standards area of Research Institute for Physical Measurement in
NMIJ, partly in collaboration with several other institutes in the Advanced Industrial Scienceand Technology (AIST).

In the five research groups of the electrical standards area, theApplied Electrical Standards Group and the Quantum Electrical Standards Group covers A3
Field.
The Quantum Electrical Standards group has developed an integrated quantum voltage noise
source (IQVNS) that is fully implemented with superconducting circuit technology for Johnson
noise thermometry (JNT) [Urano et al, 2016]. For precise measurements of Boltzmann’sconstant, the IQVNS chip was designed to produce intrinsically calculable pseudo-white noise
to calibrate JNT systems. On-chip real-time generation of pseudo random codes with simple
circuits achieved pseudo voltage noise with a harmonic tone interval less than 1 Hz, which was
one order of magnitude finer than those of conventional quantum voltage noise sources.
A liquid-helium-free PJVS has been utilized since 2015 for calibrations of Zener voltage
standards with the CMC values, 8.0 nV for 1 V and 45 nV for 10 V, same as those for ourconventional JVS system cooled with liquid helium [Takahashi et al., 2015]. The first directcomparison between our cryocooler-based PJVS system and the BIPM’s new transportable
PJVS system that is cooled with liquid helium has been carried out at NMIJ. The agreement
within 5 × 10–12 at the output DC level of 10 V was confirmed between both the systems [Chenet al., 2015]. We are now attempting to develop an AC voltage calibration system using PJVS[Maruyama et al., 2015a]. Development of Zener voltage standards are also now in progress in5collaboration with ADC Corporation [Maruyama et al., 2015b].

Fig.1 Prototype of a Zener votage standard.
Development of compact and ultra-stable 1 Ω, 10 Ω, 100 Ω and 1 kΩ standard resistors has
been finished [Kaneko et al., 2016a] [Domae et al., 2015a], and 10 kΩ resistors are in progressof evaluation and development. In 2016, we have finalized ~4 years of evaluation of 1 Ω and 10
Ω resistors, and the drift rates of those range of resistors are around 0.05 ppm/year and thetemperature coefficients are around less than 0.1 ppm/˚C. Vibration test has been also carriedout for 100 Ω resistors and showed no effect by the harsh (frequency: 16.7 Hz, amplitude: 4 mm
in 3 axes) condition. It is demonstrated that this excellent performance is suitable for utilizationin national metrology institutes and international comparisonsFig. 2 Resistance histories (drifts) of 1Ω resistors.
Conventional single Hall bar QHR devices have been fabricated and several devices have been
provided for several NMIs [Domae et al., 2015b].
Newly designed 1 MΩ quantum Hall array resistance standard devices also have been
fabricated. This device consists of 88 Hall bars on 8 × 8 mm2 GaAs/AlGaAs chip and its
nominal value has only -0.0342 ppm difference based on RK-90 from the integer value of 106.

6

Fig. 3 Picture and Hall and longitudinal resistance curve of 1 MΩ array device.
To establish a relationship between the physical structure of electrical contact boundary andcontact resistance, NMIJ developed a method for evaluating that using a physical simulated
sample created via nanofabrication. Several samples with various diameter of "contact area"
were made and their resistances were measured precisely. After removing influence of thicknessof electrodes, it was demonstrated experimentally that our result is in good agreement with an
expression for constriction resistance.
Towards a realization of the current standard based on the single-electron pumping, weinvestigate the physics of low-temperature electron transport phenomena in various types ofsingle-electron devices, i.e. superconductor-insulator-normal-insulator-superconductor (SINIS)
turnstiles, gate-confined quantum dots, and graphene- or nanotube-based single-electrontransistors [Kaneko et al., 2016b].
On SINIS turnstiles, in our early studies, we had discovered the new phenomenon that is areduction of the single-electron pumping error induced by a weak magnetic field applied to thedevice. However, the origin of this phenomenon had remained poorly understood. To elucidate
the underlying mechanism, we performed detailed measurement and analysis. First, in order toconfirm the reproducibility of this phenomenon, we compare two SINIS devices of the identicalstructure each of which is fabricated with the aid of completely different nano-fabrication
facilities and confirm the reproducibility as well as the universality. We then elucidate themechanism based on a numerical simulation of the quasi-particle state in the lead electrodes.
Aiming at further reducing the pumping error, we extended the research to that based on anotherpumping mechanism. In one instance, we investigated a GaAs-based gate-defined quantum dot
and demonstrated single-parameter pumping. In addition, we developed an air-bridge based
parallel integration of this pump to demonstrate a synchronized parallel pumping that can
7generate a larger current otherwise unattained [Nakamura et al., 2015]. In this study, molecularbeam epitaxy growth of high-quality and gate-stable GaAs hetero-structure wafer is critical forthe further development of the pumping accuracy. So, the improvement of the wafer quality is
our future plan.
In addition to the single electron pumping, we start the experiment of the error counting using
RF-reflectometry. The ac signal around a few hundred MHz signal is applied to the matchingcircuits in the dilution refrigerator. Using homodyne detection, we can succeed to detect the few
tens MHz of impedance change of the device. Also we fabricated the capacitive coupled single
electron device, namely single electron pumping device and single electron counter. Now wehave plan auto correction system using arbitrary wave generator, FPGA and charge detector.
This will make the improvement of the pumping accuracy and give us the intuitive informationof the origin of charge pump errors. Alongside of these experiments, we also developed a new
dilution refrigerator setup for measuring tiny ac current by employing low-noise
superconducting-quantum-interference-device-based

current

amplifierasthefirst-stage

amplifier. The measured current noise floor of this setup was at least one order of magnitudeimproved than that obtained with the setup that employs a semiconductor-based cryogenic
current amplifier at the first-stage. We plan to take advantage of this setup to investigate various
kinds of phenomena including non-equilibrium electron transport in mesoscopic devices andmicro electromechanical systems.
These single-electron devices are planned to be integrated with the quantum metrology
triangle experiment that combine the single-electron device with the quantum Hall resistanceand Josephson voltage standards. Towards this futuristic experiment, we had introduced a dry
dilution refrigerator; the large sample open space offered by this refrigerator allows us to
integrate the whole components required for the triangle experiment including a cryogenic
current comparator into one system. Electric noise filters and high-frequency wiring are now
designed and constructed to complete this setup.
We have been studying for measuring electric characteristics of lithium-ion batteries (LIBs)
and super-capacitors by using an impedance spectroscopy method. Aim of this work is toestablish the precision testing technique of charge-discharge cycle dependence of thecharacteristics which can provide an effective tool to examine the lifetime prediction of theenergy-storage devices. Cycle dependence of impedance was measured for cylindrical
18650-type LIBs by our electrochemical impedance measurement system. We obtained therelation of charge-discharge cycle vs internal resistance components which were estimatedbased on the results of the impedance and on the equivalent circuit models. We are now
engaging the improvement of the measurement system including measurement fixtures which
are suitable for lamination-type batteries.
8

NMIJ has started a calibration service for rechargeable battery's impedance meters.
Calibration range, 1 Ω - 100 Ω at 1 kHz, is a crucial for monitoring the long-term performance
behavior of the batteries under test. Expanded uncertainties were estimated to be 0.13 mΩ/Ω inthe range from 1 Ω to 10 Ω and to be 25 µΩ/Ω in the range from 10 Ω to 100 Ω (k = 2).

Fig. 4 Electrochemical impedance measurement system and fixture for measuring
18650-type batteries.

AC resistor calibration service has been kept in the range of 10 Ω up to 100 kΩ at 1 kHz and
10 kHz. Standard capacitor (dry-nitrogen or used silica dielectric) calibration service has been
kept in the range of 10 pF up to 1000 pF at 1 kHz, 1.592 kHz.
NMIJ has provided ac-dc voltage difference transfer calibration of thermal converters in thevoltage range from 10 mV to 1000 V and in the frequency range from 10 Hz to 1 MHz. We havebeen participating in APMP Comparison for "APMP.EM-K12" of AC/DC current transfer
difference.
Toward a low-frequency AC voltage standard down to 10 Hz, we have extended the voltage
range from 3 V to 10 V root-mean squared amplitude in AC-DC difference measurements of athermal-voltage converter using our AC-Programmable Josephson voltage standard system. The
overall uncertainty was evaluated as 1.1 μV/V (k = 2) for the frequency of 62.5 Hz. The
measurement uncertainty showed a significant improvement compared to the conventional
method based on a theoretical approach in the frequency range below 100 Hz [Amagai et al.,2015a].

9

Fig. 5
With regard to a regular calibration service, we have provided a calibration service of AC
voltmeters using a thermal converter in the frequency range from 4 Hz to 10 Hz, 40 Hz to 100
kHz at the RMS voltage of 10 V, and 1 V.
Toward a waste-heat recovery, we have launched a new project toward Seebeck coefficientmetrology that is the most fundamental physical property in the research field of thermoelectricenergy conversion. To fulfill our purpose, we have developed a new method to determine
absolute Seebeck coefficient using a Thomson-coefficient integration technique, and asuperconductor thermocouple technique [Amagai et al, 2015b]. So far, we have measured theabsolute Seebeck coefficient of Pt using a superconductor thermocouple technique, because thethermoelectric power in the Meissner state is sufficiently small. In our experiment, byemploying a Bi2Sr2Ca2Cu3O10+δ superconductor, the absolute Seebeck coefficients of the Pt
sample have been determined in the temperature range up to 100 K.
Seebeck coefficient of Pt (μV/K)

7.0

YBCO reference
Bi-2223 reference
Pb reference

6.5
6.0

Bi-2223
Tc =102 K

5.5
5.0
4.5
4.0

YBCO
Tc =90 K

75

Fig. 6

10

80

85
90
95
Temperature (K)

100

105

A4. EM Field, Power Density and Antenna Measurement
The Electromagnetic Fields Group in the electrical standards area of NMIJ takes charge ofantenna properties, electric fields and magnetic field standards.
A calibration service for the free-space antenna factor on loop antenna has been kept in thefrequency range of 20 Hz to 30 MHz. The Draft A report of APMP supplementary comparison
APMP.RF-S21.F is made circular among KRISS, NMIA and NMIJ since February 2017.
AC Magnetic field sensor calibration service has been kept in the range of 1 uT up to 150 uT
at 50 Hz and 60 Hz.
Calibration of the dipole antenna factor above a ground plane from 30 MHz to 1 GHz withthe specific conditions (with horizontal polarization and at 2.0 m from the ground surface) isavailable. The free space dipole antenna factor in an anechoic chamber from 1 GHz to 2 GHz isalso available.
The free space antenna factor calibration service for broadband antenna for Biconical antenna(30 MHz to 300 MHz) and Log periodic dipole array antenna (300 MHz to 1000 MHz) arebeing performed using our original three antenna calibration method. Super broadband antenna(30 MHz to 1000 MHz) calibration service has been started from June 2015.
Calibration services for the gains of standard horn antennas are being performed from 1.7
GHz to 2.6 GHz and 18 GHz to 26.5 GHz using an extrapolation method.

An antenna gain

calibration service for ridged guide broadband horn antenna (1 GHz to 6 GHz) is available.
An antenna gain calibration service for millimeter-wave standard gain horn antenna is being
performed form 50 GHz to 75 GHz and 75 GHz to 110 GHz using a time-domain processing
and extrapolation technique.
The calibration system of monostatic Radar Cross Section (RCS) for a trihedral cornerreflector in W-band has been developed. The RCS calibration range is 3 dBsm to 12 dBsm at 75
GHz and 6 dBsm to 15 dBsm at 110 GHz. This RCS range corresponds to the reflector size L
ranging from 75 mm to 125 mm. The expanded uncertainty of RCS was estimated to between
0.90 dB and 1.32 dB. This RCS calibration service has been started from June 2015.

11

17
PO

16

MoM
Proposed Method

RCS (dBsm)

15
14
13

L

12
11
10

75

80

85

90
95
Frequency (GHz)

100

105

110

Fig. 7 RCS calibration results in W-band and an example of a trihedral corner reflector
The E-field transfer probe calibration from 20 MHz to 2 GHz in a G-TEM cell is available.
The correction factor of a probe under calibration is provided when the probe output is 10 V/m.
A TEM cell is employed as the standard E-field generator at low frequencies and the free space
dipole antenna factor is used for the standard field generation in the anechoic chamber above
900 MHz. An optical E-field probe is employed to transfer the standard E-field strength into the
G-TEM cell. [Kurikawa et al., 2016]NMIJ has been studying a terahertz calorimeter for measuring absolute power of a terahertz
beam [Shimada et al., 2015]. We have succeeded in calorimetric measurement of the absolute
power at 1 THz at sub-microwatt levels. The expanded uncertainty was estimated as 2.4% at
0.59 μW. The minimum measurable power level was expanded up to 30 nW.

Fig. 9 Prototype of Twin type THz Caloriemeter
NMIJ has participated in a comparison of transmittance using terahertz time-domain
12spectrometers among three institutes (NMIJ, NICT, RIKEN) to verify equivalence ofmeasurements from different measurement systems. We have discussed to provide practiceguidelines in transmittance measurement [Mizuno et al., 2016].
NMIJ is doing research on new terahertz detectors. We have demonstrated a terahertz pulse
detection using a multilayer topological insulator [Makino et al., 2016].
We have developed a planar and a cylindrical scanner system for near-field antenna
measurement using photonic sensor that is a few of grams in weight and a few of millimeters
long. The systems are available about below 10 GHz.
We have developed an antenna radiation planar measurement system using photonic
technologies. The systems are available about below 120 GHz.
We have developed a radio over fiber (RoF) transceiver usable attached to an RF network
analyzer by microwave photonic technologies. It has a function of optical signal transmission
and two-way conversion of E-O and O-E. Because the RoF transceiver is available being
directly connected to antenna terminals and fed by only optical fibers, it does not affect theantenna characteristics and will become an ideal tool for antenna measurements [Kurokawa etal., 2016a] [Kurokawa et al., 2016b].
NMIJ is now researching and developing material characterization, i.e. dielectric permittivity
measurements, at the microwave frequency. NMIJ has originally developed dielectric
permittivity analysis with uncertainty optimization in the transmission/reflection measurement
method for coaxial and waveguide lines [Kato Y., 2016a]. In the millimeter-wave frequency
range, two types of free space measurement systems have been designed and installed. They are
now being optimized and estimated the measurement uncertainty from 50 GHz to 330 GHz.
Furthermore, NMIJ as a pilot laboratory, switched from NIST, will start the Pilot study for
dielectric permittivity measurement proposed by NIST as a former pilot laboratory in it. NMIJ
is now considering and selecting the transfer material standards in the comparison. We are now
proposing that two shapes of the transfer materials will be measured; plate samples by using the
split-cylinder and/or split-post resonator methods, and block samples by using the waveguide
method [Kato et al., 2016b] [Kato et al., 2016c].
A5. Power Attenuation and Impedance Measurements
The Applied Electronics Standards Group, the Radio-Frequency Group and theElectromagnetic Measurement Group in the elctrical standards area of NMIJ covers the A5
fields.
The NMIJ AC current ratio calibration system is renewed to extend the current range up to
100 amperes (current ratio up to 1000/1) in the frequency range between 45 Hz and 1 kHz[Yamada et al., 2015]. Over 1 kHz, the maximum input current is 50 amperes up to 4 kHz.
13

Temperature influence due to the increase of input current has been investigated and theuncertainty of the entire calibration system is updated. The detail will be prepared as aconference paper.
A new evaluation method for wideband voltage dividers has been proposed and presented at
the CPEM 2016. The method is based on introduction of two phase-locked reference voltage
generators to a voltage divider evaluation system for their input and reference output. The
system constructed allows wide voltage ratio and wideband evaluation for voltage dividers up to
1 MHz. The wide voltage ratio also includes decimal ratios (such as 1.01 V/100 V).
JEMIC has provided the primary active/reactive power/energy standards for the power
frequencies in the voltage range from 50 V to 120 V and in the current range from 2.5 A to 50 A
[Kawagoe et al, 2010].

The standard individually measures voltage U and current I with two

precise voltmeters and a shunt resistor, and phase θ with a precise digital phase meter. Afterthese measurements, the active and reactive powers are calculated by UIcosθ and UIsinθ,
respectively. The representative expanded uncertainties under conditions of 100 V and 5 A are
22 µW/VA (power factor 1) and 10 µW/VA (power factor 0). In 2016, we calibrated 10 power
meters and 70 energy meters.
JEMIC has been participating in APMP Key Comparison for "APMP.EM-K5.1" of AC powerand energy.
The calibration system for WR-15 power meter was renewed. A frequency multiplier was
substituted for a conventional backward-wave oscillator (BWO). NMIJ are developing a new
calorimeter for a higher frequency range up to 330 GHz.
NMIJ has successfully established an RF attenuation standard system in the frequency rangeof 33 GHz to 50 GHz (Q-band), and started the jcss calibration service from June 2015 [Widarta
et al., 2014]. The system is built by using the simple intermediate frequency (IF) receivertechnique using a resistive step attenuators operated at 30 MHz, as an IF attenuation reference
standard and a general-purpose receiver, as a level detector. By increasing the IF to 30 MHz, thenoise effects caused by higher RF signals, such as the Q-band, can be kept small. This condition
also allows us to use a general-purpose receiver as a sensitive level detector that facilitates theautomation and long-term maintaining to the system. Traceability of the system then is ensured
by performing periodic calibration to the IF attenuator reference standard at 30 MHz using the
NMIJ attenuation standard system based on the voltage ratio of the IVD at 1 kHz.
Establishment of an attenuation reference primary standard in the frequency range of 110
GHz to 170 GHz has been also started [Widarta, 2016]. A millimeter wave VNA system, which
consists of an intermediate frequency VNA and a set of millimeter wave S-parameter test
extenders, is used as a measurement system. The traceability is ensured by the calibration to theintermediate frequency ports of the VNA using the calibrated step attenuator at 10.3 MHz.
14NMIJ took an initiative to organize a CIPM Key Comparison of attenuation at 18 GHz, 26.5
GHz and 40 GHz using a step attenuator. This comparison has been registered in the KCDB
under the identifier CCEM.RF-K26, with 15 laboratories (countries) declared to participate.
Measurements of the first round loop can be said successful, although there were some delays inthe delivery of the traveling standards between the participants. Currently, is in the second roundloop and expected to be completed around June 2017.
A bilateral comparison of millimeter-wave attenuation in V band (50 GHz to 75 GHz) was
performed between NMIJ and NMC [Iida et al., 2016a]. Good agreement of the measurement
results between both laboratories was verified in the attenuation range up to 60 dB.
The terahertz waveguide flange, NMIJ developed, was standardized in the IEC 60154-2
standard. It provides precise connection and connection reproducibility [Horibe, 2016a][Horibe ,2016b] [Horibe et al., 2016c] [Horibe et al., 2016d].
NMIJ is researching the material characterization at millimeter-wave frequency, precision
on-wafer measurement techniques, printed electronics at millimeter-wave and non-linear
load/source-pull measurement for GaN active devices [Horibe et al, 2016e] [Kishikawa et al.,2016a] [Kishikawa et al., 2016b] [Sakamaki et al., 2016a] [Sakamaki et al., 2016b].
Furthermore, electromagnetic sensing techniques are also researching for the agriculture
products and food [Kon et al., 2016a] [Kon et al., 2016b].
Furthermore, NMIJ as a pilot laboratory is managing the CCEM key comparison(CCEM.RF-K5c.CL: S-parameter for PC3.5 in the range from 50 MHz to 33 GHz),, the APMP
supplemental

comparison(APMP.EM.RF-S5.CL:

Dimensionally-derived

characteristic

impedance for PC7, PC2.4 and PC1.85) and will start the pilot study for material
characterization.
NMIJ has demonstrated terahertz attenuator calibration using the calorimeter. We have shown
measurement capability up to 12 dB with an expanded uncertainty of 0.19 - 0.84 dB (k = 2) at 1
THz [Iida et al., 2016b].

15

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18

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