COMMISSION A : Electromaganetic Metrology (November 2007 –October 2010)
Edited by Masatoshi Kajita and Yasuhiro Koyama, National Institute of Information
and Communications Technology
A1. Time and Frequency Standards and Time Transfer Technique
In Japan, the researches and developments on Time and Frequency (T&F) Standards andTime Transfer Techniques are mainly carried out in the National Institute of Information andCommunications Technology (NICT) and National Metrology Institute of Japan (NMIJ).
NICT has developed a cesium atomic fountain primary frequency standard NICT-CsF1.
[Circular T, Kumagai et al., 2008a, b]. The typical uncertainty was 1.5×10-15 including theuncertainty of the link. To improve the short-term stability of NICT-CsF1, the authors haveintroduced the cryogenic sapphire oscillator (CSO), which developed in the University ofWestern Australia. The stability improved by a factor of 3. And, to reduce the systematic
uncertainty, the authors have started to develop our second atomic fountain (NICT-CsF2). So
far, the authors have succeeded to observe 0.95 Hz Ramsey signal in NICT-CsF2.
NICT newly developed a Network Time Protocol (NTP) server with high-performance andstarted a public time service from 2007. The number of access was about fifteen million per day
in 2007 and is more than one hundred million per day in 2010. A new protocol for high-speed
network time transfer has been investigated by using this server. NICT also developed a GPS
receiver with network for a remote calibration and time transfer [Machizawa et al. 2008] andreconstructed more convenient system [Iwama et al. 2010]. Then NICT transferred thetechnology of a GPS receiver to a commercial company.
NICT is regularly performing Two Way Satellite Time and Frequency Transfer (TWSTFT)
between Germany (PTB) and Asian T&F institutes (KRISS, TL, NTSC, SPRING, and NMIJ),
and calibrated their station delays for TL, KRISS and NMIJ. Obtained data by TWSTFT and
GPS are reported to BIPM. The TWSTFT data for NICT/PTB link has been adopted for TAI
link since April 2007 in place of GPS data. The number of participants of this Asia-Eu link
sharply increased. At last 6 Asian and 2 European institutes (NICT, KRISS, NMIJ, TL, NTSC,
NIM, PTB and OP) joined. After the link pause for half year due to the satellite malfunction, thelink restarted by switching the satellite on October 2010. Causes of observed diurnal variation
have been studied, especially compared before and after the switch. By the install of a relay
station in Hawaii, the link between NICT and USNO was established by 2-hop connection on
July 2010. The result shows good agreement with GPS PPP.
NICT developed a new TWSTFT modem using Dual Pseudo-random Noise (DPN) signal.
NICT carried out TWSTFT experiments with DPN signal between NICT and TL, as well asconfirmed that short (< 100 sec) and long (< 1 day) term stability of the DPN system were lessthan 50 ps and less than 200 ps respectively. DPN method was also adopted for QZSS narrow
band bent pipe system, and used for time comparison between NICT Koganei and Okinawa
earth stations. NICT developed GPS carrier phase time transfer software “concerto version 4”.
The software can analyze both methods, PPP and single difference observations, and be used forthe evaluation of DPN method. The results of DPN and GPS carrier phase were consistent
within 100 ps per 1 day.
NICT developed an RF distribution system using optical fibers, which has an active
phase-noise cancellation system. The system was evaluated in the JGN2plus optical fiber link
which was an urban optical fiber link in Tokyo [Fujieda et al. 2009]. The transfer stability in the
10-18 level at an averaging time of 1 day was achieved in the 114-km frequency dissemination[Kumagai et al. 2009]. In addition, the transfer length was extended to 204 km by a cascaded
system, which stability was still in the 10-17 level [Fujieda et al. 2010]. For direct comparison of
optical clocks, an optical carrier transfer system has been developed, too. Two 87Sr opticalclocks were compared using a 60-km optical fiber link in the 10-16 frequency resolution. Its shortterm stability in the 10-15 level enabled us the real time detection of the frequency difference of
10 Hz.
NICT achieved pico-second order precision for two-way time and frequency comparison
between the ground clock and the on-board atomic clock on ETS-8 satellite, which waslaunched in December 2006. Both code phase and carrier phase showed consistent result andcapability to monitor the on-board atomic clock. [Takahashi et al. 2008]
NICT developed the time management system, which consists of on-board equipment and theground segment of the Quasi-Zenith Satellite System (QZSS) which is a regional satellite
navigation system in Japan. Its first satellite QZS-1 was successfully launched on September,2010. Various experiments such as precise T&F comparison between the QZS-1 andUTC(NICT) and between two ground stations, on-board atomic clock monitoring, L-band
calibration, are now been carrying out [Hama et al. 2009]
In NMIJ, following researches have been conducted. Primary Frequency Standards; NMIJ
has made the calibration of the International Atomic Time (TAI) 18 times between 2007 and2010 with the Cs atomic fountain frequency standard, NMIJ-F1 with a combined uncertainty of
3.9×10-15 [Circular T, Yanagimachi et al. 2008, Takamizawa et al. 2010]. NMIJ-F1 will be used
as a reference oscillator for the evaluation of the optical lattice clocks in NMIJ, the developmentof our second fountain (NMIJ-F2), as well as used for the TAI contribution. The construction of
NMIJ-F2 has been continued. A truncated atomic beam fountain was proposed and the proof ofthe principle experiments has been started, in order to achieve a low collisional frequency shift,high frequency stability and the uncertainty of the order of 10-16 [Takamizawa et al. 2010].

Ultra-stable microwave oscillator; NMIJ has been maintaining two cryogenic sapphireoscillators (CSOs) for use as a local oscillator of Cs atomic fountains and a reference oscillator
for the evaluation of ultra-stable lasers in optical lattice clocks.
Time Keeping; Four cesium atomic clocks with high-performance beam tubes (Agilent
5071A) and four active hydrogen maser frequency standards are operated for time keeping in
NMIJ. One of the hydrogen maser frequency standards has been used for the generation of
UTC(NMIJ) since March 2006 to improve the short term stability of UTC(NMIJ).
Time and Frequency Transfer; In NMIJ, dual frequency carrier phase GPS receiver is one of
the main international time and frequency transfer tools. In addition, NMIJ has the Two Way
Satellite Time and Frequency Transfer (TWSTFT) facilities for Asia Pacific link and for
Asia-European link.
An optical fiber bidirectional frequency transfer system using Wavelength Division
Multiplexing technology is also studied in NMIJ as one of future precise time and frequency
comparison systems [Amemiya et al. 2006, Amemiya et al. 2010a, Amemiya et al. 2010b].
Frequency Calibration Service; NMIJ and related organizations have been conducting toconstruct remote calibration systems for several metrology areas since 2001. Time andfrequency division of NMIJ has been developing a frequency calibration system using GPS
common-view method and Internet. NMIJ's remote frequency calibration service has been
started since 2006 to the calibration laboratories. NMIJ has also started to develop the user
equipment for the end users of the remote frequency calibration service [Imae et al. 2010]. A
simple and cost effective frequency dissemination method also has been developed in NMIJ. In
this method, optical fiber network service (INS-1500) is used for generating 10 MHz reference
signal. Stability test results showed a good performance with an uncertainty of less than 1×10-12
at an averaging time of one day [Amemiya et al. 2008].
A2. Laser Stabilization and Frequency Measurement
The researches and developments in Japan on the stabilization of lasers and the opticalfrequency measurement are also mainly carried out in the National Institute of Information andCommunications Technology (NICT) and National Metrology Institute of Japan (NMIJ),
together with some very active universities.
NICT is developing a single Ca+ ion trap optical frequency standard. Matsubara et al. havemeasured the absolute frequency of the 4s2S1/2 - 3d2D5/2 forbidden transition, and the frequency
uncertainty is reduced down to 5 Hz [Matsubara et al., 2008 a,-c, 2009 a-b].
NICT is developing also an optical frequency standard based on the Sr 1S0 – 3P0 forbidden
transition in a optical lattice. The frequency uncertainty is of the order of 0.2 Hz [Yamaguchi etal. 2010 a].

Li et al. developed clock lasers with linewidth narrower than 3 Hz [Li et al. 2008 1.-b, 2010a]. Also the new system to transfer the stable laser frequencies to a distant place via opticalfibers [Fujieda et al. 2009, Kumagai et al. 2008 c, 2009].
To measure the laser frequency, NICT has operated two optical frequency combs based on
Ti:Sapphire laser with the uncertainty at 10-17 level [Nagano et al., 2009] and is developing
fiber laser frequency combs. The fiber combs measure their relative frequency stability
and estimate the stability as 5×10-13 and 1×10-15 at averaging time of 1 s and 500 s respectively.
The Allan variance of the ratio between Ca+ - Sr transition frequencies was measured to be
3×10-16 with the measurement time 2000 sec..
Various time and frequency standards related researches have been conducted in NICT andsome Universities, such as on atomic and molecular physics. Kajita has proposed an infrared
frequency standard based on the vibrational transition frequencies of magnetically trapped XH
and XLi molecules, and XH+ molecular ions (X: even isotopes of group II atoms) [Kajita 2008
a,b, 2009 a-e, 2010a-b].
NMIJ is developing an 171Yb optical lattice clock. They have succeeded in the first absolute
frequency measurement of the 1S0 – 3P0 clock transition of 171Yb with an uncertainty of
5.4×10-14 [Kohno et al. 2009]. Progress is under way to reduce the uncertainty by increasing thesignal to noise ratio of the observed spectrum using the atom number normalization scheme.
They have developed a fiber-comb-stabilized light source at 556 nm for magneto-opticaltrapping of ytterbium, which is necessary for obtaining ultracold ytterbium atoms trapped in an
optical lattice [Yasuda et al. 2010]. NMIJ has also started a new project on Yb/Sr dual opticallattice clock project in 2009. They developed a compact light source for 1st stage cooling of Sr
using a periodically poled lithium niobate waveguide [Akamatsu, et. al. 2010] and successfully
magneto-optically trapped both species in the same chamber. NMIJ has developed advanced
optical frequency combs based on erbium-doped fiber laser (fiber comb). Robustness, usability,
and servo bandwidth has been improved. For example, NMIJ have established the national
standard of length in Japan by using a fiber comb. On the other hand, a fiber comb with
mHz-level relative linewidth was realized using an intra-cavity electro-optic modulator[Nakajima et al. 2010]. They utilized the narrow linewidth fiber comb to develop the lightsource for the clock transition of Yb and the 2nd stage cooling of Sr. In the clock laser system,
the highly stabilized fiber comb is able to transfer the linewidth and frequency stability from one
laser frequency to another and it plays a role of an ultra-stable local oscillator for multi wavelengths.
The clock laser at 578 nm for the Yb optical lattice clock has been phase locked to one of the comb
modes. The authors have demonstrated spectroscopy of the clock transition in Yb atoms with the
new clock laser system.

Katori group at University of Tokyo developed lattice clocks using 87Sr and 88Sr [Akatsuka etal. 2008]. Takamoto et al. discussed also the possibility to trap Sr atoms with a blue detuned
laser [Takamoto et al. 2009]. Hachisu et al. started to develop an Hg optical lattice clock[Hachisu et al. 2008].
The frequency transfer between Katori group and NMIJ, that made possible to compare the Srlattice clock and NMIJ-F1 [Hong et. Al. 2009]. In 2010, the direct frequency comparison
between Sr lattice clocks in Katori group and NICT was performed.
A3. Realization of Electrical Units (DC & LF)
Research works and developments on dc and low frequency electrical standards, that is,standards for dc voltage, dc resistance, ac resistance, capacitance, inductance, ac/dc transfer etc.,
are implemented in Electricity and Magnetism division of National Metrology Institute of Japan(NMIJ), partly in collaboration with several other institutes in Advanced Industrial Science andTechnology (AIST).
NMIJ has been developing a pulse-driven (10 mV, rms) and programmable (3 V, rms)
Josephson arbitrary waveform synthesizers (JAWS) based on the over-damped Josephson
junction arrays (JJAs). NMIJ has adopted pulse-tube-type mechanical cryocoolers and newly
developed wide band chip carriers for this project. The cryocoolers have extremely low
mechanical noise and the chip carriers are equipped with 20 or 32 coaxial inputs/outputs ofwhich the outer conductor are electrically separated to suppress ground loop noise [Kaneko et al.
2010, Urano et al. 2009a, 2009b, Maruyama et al. 2009, Maruyama et al. 2010].
Devices of quantum Hall array resistance standard (QHARS) with a nominal value close to
10 kΩ on the i = 2 plateau have been developed on a GaAs/AlGaAs hetero-substrate. ThisQHARS device consists of just 266 Hall bar elements, and its nominal value has only 0.0342
ppm difference based on RK-90 from the integer value of 104. As a result of comparison
measurement with the conventional Quantized Hall Resistance Standard via a 100-Ω standard
resistor, the difference between the measured value and nominal value is less than theuncertainty level of 1.0×10-8. We plan to fabricate and evaluate several types of QHARS
devices and confirm the reliability of the devices [Oe et al., 2008, 2010a].
Stable standard resistors (1 Ω to 10 kΩ) are now being developed in collaboration with AlphaElectronics. 100-Ω standard resistors of which temperature coefficients are extremely low, lessthan 0.1 ppm/degree, and resistance values are greatly stable, less than 0.1 ppm/year have beensuccessfully manufactured and in market. Resistors with other nominal values are also underdevelopment [Sakamoto, Y et al., 2010].
Capacitance standards from 10 pF to 1000 pF are established at NMIJ based on the QuantizedHall Resistance at dc with an ac/dc calculable resistor and a quadrature bridge [Nakamura et al.,2010]. NMIJ has planned to derive the capacitance values from the AC-QHR in the future. The

new quadrature bridge to link capacitance to the AC-QHR is now being developed [Oe et al.,2010b]. Higher values of capacitance with dissipation factor from 0.01 μF to 10 μF are alsoestablished at NMIJ using a four-terminal-pair (4TP) impedance bridge with a 10:1 voltage ratio
transformer.
NMIJ has developed a capacitance-scaling bridge using a current comparator and an
inductive voltage divider for calibrating 4TP-defined capacitance standards of 100 μF. The
expanded uncertainties of the capacitance and the dissipation factor of 100 μF at 120 Hz are 11
μF/F and 14 μrad, respectively. The bridge was recently modified aiming to calibrate thestandards of 1 mF. Estimations of the uncertainties of 1 mF are now in progress [Sakamoto, N etal., 2010].
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.
Practical thin film multi-junction thermal converters (MJTC) have been also developed incollaboration with NIKKOHM Co. Ltd. Our device has the thermoelectric transfer difference ofbetter than 0.2 μV/V and frequency characteristics of the ac-dc transfer differences wereconsiderably improved in the range between 10 Hz and 1 MHz [Sasaki et al., 2010]. NMIJ has
developed AC voltmeter calibration system by using a planar MJTC in the frequency range
from 40 Hz to 100 kHz and at the voltage of 10 V [Amagai et al., 2010]. NMIJ has planned toextend the frequency range down to 5 Hz and the voltage range down to 1 V. Also, we havebeen developing a planar MJTC for improving low-frequency characteristics below 100 Hz andthe long-term stability. Employing a new thermopile pattern, the stability of the planar MJTC
has been improved.
NMIJ has developed a harmonic voltage and current measurement standard. The standard has
been confirmed that it has the uncertainty level of 40 ppm – 80 ppm up to 50th harmonics bymeans of using AC calibrators as AC reference standards. The feasibility of a power
measurement capability of the standard has also been confirmed that it has uncertainty level of
20 ppm in the comparison of a power meter between Japan Electric Meters Inspection
Corporation (JEMIC) and NMIJ [Yamada et al., 2010].
NMIJ has developed a calibration system for the AC shunt standard of the current range from
1 A to 10 A and the frequency range from 50 Hz to 400 Hz [Kon et al., 2010].
A4. EM field, Power density and antenna Measurement
A dipole antenna is a simple linear antenna, and this result in the accuracy andhigh-selectivity of the field polarization. Since many electromagnetic compatibility/electromagnetic interference (EMC/EMI) measurements below 1 GHz are implemented on a
ground plane, responses of the antenna employed in these measurements should contain theeffect of the coupling with image. However, free space antenna factor (AF) is often used for themeasurements even above the ground plane, and errors are introduced by few decibels
especially at lower frequencies. To overcome this problem and considerable efforts in themeasurements, a prediction method of the height-dependent AF and mismatch effects have been
proposed [Morioka et al. 2010b]. Measurements in an anechoic chamber become common
above 1 GHz. Some EMC test regulations require measurements in this frequency range. Since
the measurement environment is quasi-free space, the free space AF of the antenna should becalibrated. The three-antenna method is applied and the calibration capability has been achieved
to 0.4 dB (k=2) in the frequency range from 1 to 2 GHz [Morioka 2009a].
Although the field generation in an anechoic chamber has an advantage in the frequency band,that in a transverse electromagnetic (TEM) waveguide is still useful in terms of compactness. In
addition to this, generating a strong field in the TEM waveguide requires an amplifier withsignificant lower gain compared with that in an anechoic chamber. Accordingly, it is reasonable
to use a TEM cell at a lower frequency than the higher order mode cutoff frequency of the cell.
For the use of a TEM cell as a standard field generator, the electromagnetic fields of the cellshould be accurately evaluated. A method to measure electromagnetic fields in a TEM cell byusing a passive scatterer has been proposed [Morioka 2009b]. Since the E-field of a TEM cell
varies with respect to the location, probe responses to such a non-uniform E-field have been
investigated [Morioka 2010a].
A continuous antenna factor in a wide frequency range is convenient to be used and such a
broad-band antenna as a log-periodic antenna (from 300 MHz to 1 GHz) and a bi-conicalantenna (from 30 MHz to 300 MHz) were evaluated for a metrology standard. A new method
was proposed for evaluating a free-space antenna factor continuously through a wide frequency
band. The method is based on a technique of a time-domain analysis and a pulse-compression
technology for reducing the influence by the reflected waves from surrounding obstacles. The
method was examined for calculating the free-space antenna factor of a log-periodic antenna
and a bi-conical antenna widely used for EMI measurement [Kurokawa et al. 2009, 2010a].
The developments of calibration techniques for loop antennas were carrying out by AIST.
AIST started to develop the calibration method since 2002. AIST has been providing acalibration service for small loop antennas whose diameters are about 10 cm and 60 cm in thefrequency range from 9 kHz to 30 MHz since 2007. This calibration service was expanded in
March in 2008. The target of the loop antenna’s diameter is 133 mm and the frequency range isfrom 20 Hz to 200 kHz. Basically they calibrate the standard loop antenna by the “3-Antenna
Method” and the customer’s loop antennas by the “Reference Antenna Method”. They alsostudied and proposed another more simple reference calibration method for loop antenna [Ishii
et al. 2009a].

The developments of calibration techniques for short monopole antennas were carrying out
by AIST. They proposed “3-Antenna Method [Ishii et al. 2009b]” and “Reference Antenna
Method [Ishii et al. 2010]” for short monopole antenna. These studies are in progress.
AIST started to develop AC magnetic field strength standard since 2008. They will start thecalibration service at 50 Hz, 55 Hz, and 60 Hz in 2011. The method depends on the “Standard
Field Method” using a Helmholtz-coil. On the other hand, NICT and Aoyama Gakuin
University are also developing the magnetic field sensor calibration system.
Calibration services for the gains of standard horn antennas are being performed from 1 GHz
to 40 GHz at specified 21 frequency points using transfer method. An antenna gain calibration
service for micro-wave standard gain horn antenna (1.7 GHz to 2.6 GHz) has been preparedusing a planer near-field antenna measurement method. An antenna factor calibration service forridged guide broadband horn antenna (1 GHz to 6 GHz) will be started from March 2011.
For expanding the frequency range of antenna gain standard, we have developed a calibration
system for V-band (50 GHz to 75 GHz) millimeter-wave horn antenna using the three antenna
extrapolation method. In the conventional extrapolation method, the multiple reflections
between antennas are removed by the moving average method. To reduce the long measuring
time caused by the moving average, the time-domain gating method was employed forremoving multiple reflections [Ameya et al. 2010 a].
A novel method was proposed in antenna measurements [Hirose et al. 2010]. The method
realizes antenna measurements in full 2-port calibration that requires only open-short-load
calibration at each port without through calibration because of using the unknown thru
algorithm. The residual systematic errors are completely equivalent to the conventional
unknown thru method. No need to do through calibration is especially important in antenna
measurements because we are released from the hard labor to mate cable connectors directly or
to other cable connectors.
In the EMC field, the frequency range of the EMI regulation is expanded from 1 GHz to 6
GHz in EU and Japan in 2010. To improve the EMI anechoic chamber performance above 1
GHz, we have proposed a new anechoic chamber evaluation technique using plane-wave
spectrum for finding the reflection points in EMI anechoic room [Ameya et al. 2010 b]. The
proposed method enables to obtain the intensity and the angle of arrival of reflection waves andfacilitates improving performance of anechoic chambers.
Kurokawa et al. have developed an EMI measurement system using microwave photonic
technologies. It has the function of a kind of directional findings for interferences in, forexample, an anechoic EM chamber [Kurokawa et al. 2010 b]. The system can be used from 30
MHz to 6 GHz.
Capozzoli et al. have developed planar and spherical scanner systems for near- field antennameasurement using photonic sensors that are a few of grams in weight and a few of millimeters
long. The systems are available about below 10 GHz. The authors have launched a collaborative
research with Napoli Federico II University in Italy for the phase-less near-field antennacharacterization using such photonic sensors as above mentioned [Capozzoli et al. 2009, 2010].
A5. Power, Attenuation and Impedance Measurement
In recent years, NMIJ has started to study and develop a new microwave power standard
based on quantum electronics. The new microwave power standard is directly linked withfrequency measurement via atomic Rabi frequency. The Rabi frequency of cesium atoms in a
glass cell inserted in a WR-90 waveguide was measured. Then, the magnetic field strength ofthe microwave was estimated from the measured Rabi frequency in 2008 [Kinoshita et al.,2008a, 2008b, 2008c, 2009a, 2009b, 2009c, 2009d]. The magnetic field strength was converted
into the microwave power using an analysis of the distribution of the electromagnetic field in
the waveguide [Kinoshita et al., 2010a]. It was confirmed that the microwave power measured
from the Rabi frequency is consistent with that measured by a calorimetric method within theiruncertainties [Kinoshita et al., 2010b, 2010c]. Now, the authors are improving the uncertainty
by developing a new glass cell.
In high precision attenuation measurements and standards, the mismatch is often the largest
term contributing to the systematic uncertainty. To minimize this uncertainty a RF attenuation
measurement technique, where the source and load do not have to be matched to the line
impedance, was proposed [Widarta et al, 2008a, 2009a]. The technique based on thecancellation of the multiple reflected signals in the network by performing additional loss
measurement steps to the device under test (DUT), which are fitted to quarter-wavelength (QW)
lines. The QW lines reverse the directions of the vectors of the reflected signals, and then theeffects of the mismatch are approximately canceled. This technique has the ability to measureattenuations of discrete frequencies at which the relative phase shift values of the lines to thefrequencies are 90º. Improvement to the system was done, by introducing two low-reflectivelines (airlines) where the phase shift values are already-known instead of the QW lines, inorder to extend the capability to measure RF attenuation in broad continuous frequencies[Widarta et al, 2010]. A simple IF receiver system dedicated for working standard system ofattenuation has been also developed by employing a calibrated resistive step-attenuator
assembly at 30 MHz as an IF reference standard and a general-purpose receiver as a sensitive
level detector [Widarta, 2008b].
NMIJ participated as a linking laboratory in the APMP comparison of attenuation at 60 MHz
and 5 GHz (APMP.EM.RF-K19.CL) [Gao et al, 2010].
Calibration service for RF attenuation in the frequency range of 50 – 75 GHz (V-band) wasstarted to meet the demands for accurate and traceable measurement in the industry. A new
primary attenuation standard for the V-band was developed [Iida et. al. 2010]. Based on the IF
substitution method, it employs an inductive voltage divider (IVD) working at 10 kHz as areference standard. A highly stable IF signal is obtained for precision measurement using
phase-lock technology on the frequency-converted local signal.
For the noise standard, an original cryogenic standard noise source with WR90 waveguideflange was constructed in the frequency range of 8-12 GHz [Iide et. al. 2008, 2009a]. The noise
temperature and uncertainty of the noise source were evaluated by a sliding short method using
a total-power radiometer. In order to expand the frequency range of the standard noise source,
NMIJ was also developed a cryogenic 7-mm coaxial noise source and its evaluation method[Iida et. al. 2009b]. The noise temperature of the coaxial noise source was calibrated by using an
auxiliary transmission line. The contribution of the noise generated from the transmission lines
was estimated by the available power ratio of the transmission line and the radiometermeasurements in particular conditions.
NMIJ has started the joint research project with National Physical Laboratory, UK. In thecollaborative work, it is clear that the dimensional calibration capabilities of coaxial air line, i.e.
3.5 mm line size and 1.85 mm line size, were good agreement between both laboratories[Horibe et al., 2007, 2008c, 2010a]. Then NMIJ and NPL had been developed the verification
method of phase measurements in the vector network analyzers (VNA) [Horibe et al., 2009a]. In
addition, NMIJ and NPL developed a new concept of VNA calibration standards, i.e. ‘Air
Open’ standards [Horibe, et. al., 2010e]. The NMIJ showed the calibration and measurement
capabilities for air line dimensions of 1.0 mm line size [Horibe et al., 2008a, 2009a]. The
evaluation infrastructure for the connector interface to estimate electrical characteristics of airline, then NMIJ shows a characteristic depends on the connector dimensions, i.e. male pin andfemale socket, [Horibe, 2008b]. The calibration services of the complex voltage reflection
coefficients, in the frequency range of 9 kHz to 18 GHz, have been started for PC7 connector in2010 [Horibe et al., 2009e, 2010b]. These calibration cervices are based on use of theoriginally-designed standard terminations in the range of 9 kHz to 10 MHz, then, the long
length air lines as the impedance standards are calibrated using a dimensional measurement andelectrical loss measurement [Horibe et al., 2010b]. In 2009, the development of the scatteringparameter standard for the rectangular waveguide in the frequency range of 50 GHz to 330 GHz,
have been started [Horibe et al., 2010c, 2010d. Subsequently, in 2010, the originally-designed
waveguide flanges and calibration standard were developed and evaluated.
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Gao Qiulai, Liang Weijun, Joo-Gwang Lee, Anton Widarta, Michael W K Chow, Thomas Wu5,
Stephen Grady, Mariesa Prozesky, Erik Dressler, Kamlesh Patel, P S Negi, Chairat
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Hachisu H., K. Miyagishi, S. G. Porsev, A. Derevianko, V. D. Ovsiannikov, V. G. Pal'chikov, M.
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Hirose M. and K. Komiyama, “A novel full 2-port calibration method for antenna measurement
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Hong F.-L., M. Musha, M. Takamoto, H. Inaba, S. Yanagimachi, A. Takamizawa, K. Watabe, T.

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Horibe M. and N. Ridler, “Using time-domain measurements to improve assessments ofprecision coaxial air lines as standards of impedance at microwave frequencies”, 70th ARFTG
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Horibe M., M. Shida, and K. Komiyama [2008a], “A CALIBRATION FOR PRECISION
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conference digests, pp.478-479, 2008/06
Horibe M., M. Shida, and K. Komiyama [2008b], “Quantitative Understanding of the Mated
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Horibe M. and N. Ridler [2008c], “A BILATERAL COMPARISON OF MEASUREMENT OF
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Horibe M., M. Shida, and K. Komiyama [2008d], “Time-domain and mechanical assessmentsof 1.0 mm coaxial air lines”, ARFTG 72nd Microwave Measurement Symposium Proceedings,
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Horibe M. and N. Ridler [2009a], “Comparison between Two National Metrology Institutes ofDiameters and Characteristic Impedance of Coaxial Air Lines”, IEEE Trans. Instrum. Meas,
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Horibe M. [2009c], “Metrological Traceability in Vector Network Analyzer Measurements”,
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Horibe M. and N. Ridler [2009d], “Verifying Transmission Phase Measurements at Millimeter
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Horibe M., M. Shida, and K. Komiyama [2009e], “VNA Traceability Tool”, Special
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Horibe M. and N. Ridler [2010a], Bilateral Comparison of 1.85 mm Coaxial Air Line
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Horibe M., M. Shida, and K. Komiyama [2010c], “Traceability of S-parameter Measurement of
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AP-RASC'10 digests, 2010/09
Horibe M., M. Shida, and R. Kishikawa [2010d], “Complete Characterization of Rectangular
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Horibe M., N. Ridler, M. Salter, and C. Eio [2010e], “Characterization and Verification of
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on precision electromagnetic measurements digest, pp. 700-701, 2008
Iida H., Y. Shimada and K. Komiyama [2009a], “Noise Temperature and Uncertainty
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Iida H., Y. Shimada and K. Komiyama [2009b], “Evaluation of a cryogenic coaxial noise sourcebased on the calibration method by single auxiliary transmission line,” 2010 Conference on
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Iida H., A. Widarta, T. Kawakami and K. Komiyama, “Attenuation Standard in the Frequency
Range of 50-75 GHz”, IEEE Trans. Instrum. Meas (submitted), 2010
Imae M., Y. Fujii, Y. Mitamoto1, T. Suzuyama, T. Kawakami, H. Yoshida, H. Hurukawa, and
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Ishii M., and Y. Shimada [2009a], “Reference Calibration Methods for Small Circular Loop
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Ishii M. and Y. Shimada [2009b], “A Near field 3-Antenna Method for Short Monopole
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Ishii M. and Y. Shimada, “A Reference Antenna Method for Non-resonant Electrically Short
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Iwama T., A. Machizawa and H. Saito, “Time and Frequency Dissemination-System with
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Kajita M., M. Abe and Y. Moriwaki [2010a], “Proposed detection of the variance in mp/me via
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Kaneko N., M. Maruyama, and C. Urano, “Current Status of Josephson Arbitrary Waveform
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Kawakami, T., A. Widarta, H. Iida and K. Komiyama, “Voltage ratio system constructed for RF
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Kinoshita M., K. Shimaoka and K. Komiyama [2008a], “Rabi frequency measurement for
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Kinoshita M., K. Shimaoka, K. Komiyama [2010a], “Absolute measurement of microwave
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Kinoshita M., K. Shimaoka, and K. Komiyama [2010b], “Uncertainty of Atomic Microwave
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Kon S., T. Yamada, and T. Tadokoro, “Verification and Uncertainty Evaluation of an AC ShuntCalibration System at Power Frequencies”, Conference digest CPEM2010, pp.343-344, June
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S1/2-32

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40

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Nakamura Y. and A. Domae, “National electrical standards supporting international competitionof Japanese manufacturing industries Synthesiology”, Vol.3, No.3, p.213-222, 2010
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Sasaki H., H. Yammori, T. Yamada, H. Fujiki, A. Shoji, I. Budovsky and K. Shimizume,“Evaluation of Low-Frequency Characteristic of a Thermal Converter Using Programmable
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