Tomoteru Kawakami

Attenuation measurement system in the frequency range of 10 to 100 MHz

The attenuation-measurement system of the National Metrology Institute of Japan - the dual-channel intermediate-frequency (IF)-substitution method using an inductive-voltage divider (IVD) as a reference standard - is improved to cover the frequency measurement range of 18-40 GHz. Higher accuracy is obtained by raising the IF to 10 kHz and employing two seven-decade IVDs in cascade arrangement. The use of the frequency doublers at each local port of the mixers allows the low-pass filters to be installed to satisfy the essential isolation between the channels. A 10-kHz voltage-ratio standard has been constructed and used as a reliable technique for uncertainty evaluation and long-term accuracy control of the 10-kHz null-balance receiver. The expanded uncertainties are expected to be 0.002 dB for attenuation up to 40 dB, 0.005 dB for 60 dB, and 0.03 dB for 80 dB

An accurate microwave attenuation measurement system using an inductive voltage divider based on a single-channel IF substitution method

An accurate microwave attenuation measurement system employing an inductive voltage divider (IVD) operating at 10 kHz as a reference standard, and a single-channel intermediate frequency (IF) substitution method to carry out the null balancing technique is proposed. The system is achieved by stabilizing the IF measurement signal using a phase-locked loop (PLL) technique and by introducing an independent IF reference signal for the null balancing process. The measurement accuracy is verified by evaluating the performance of the attenuation measurements compared with a dual-channel IF substitution method at 10 GHz. The tolerance for frequency purity of the signal sources is also evaluated by using a signal which is frequency modulated by Gaussian noise as a model of an unstable signal source. Experimentally, good stability of the system is obtained even with the severe conditions of the signal sources used.

Japan National Standard of Attenuation in the Frequency Range of 10 MHz to 18 GHz

An attenuation measurement system employs an IVD at 1 kHz as a reference standard and dual-channel IF substitution method is developed to renew the Japan national standard of attenuation. The new system has a measurable attenuation range of 100 dB at frequencies from 10 MHz to 12 GHz, and besides 60 dB up to 18 GHz

Attenuation Standard in the Frequency Range of 50–75 GHz

An accurate primary standard has been constructed for RF attenuation measurements in the frequency range of 50-75 GHz. Based on the IF substitution method, it employs an inductive voltage divider (IVD) working at 10 kHz as a reference standard. A highly stable IF signal is obtained for precision measurement using phase-lock technology on the frequency-converted local signal. The IVD component is a sequence of six-decade IVDs that are combined to realize an attenuation of 80 dB. They are particularly and independently fabricated to realize the improved performance in uncertainty at 10 kHz. Each IVD has independent input and output terminals; therefore, it can be individually calibrated and precisely evaluated. Measuring RF signals, including several subharmonics, is generated by a frequency quadrupler. The influence that is associated with the subharmonics is theoretically analyzed. Sources of uncertainties in the system are discussed, and the overall expanded uncertainty is found to be 0.004-0.13 dB corresponding to a measured attenuation range up to 80 dB.

A Simple RF Attenuation Measurement Technique With a Small Mismatch Uncertainty

An accurate radio frequency (RF) and microwave attenuation measurement method is described, where source and load do not have to be matched to the line impedance and where the contribution of a mismatch effect to the uncertainty is reduced to about 0.002 dB. From loss measurements carried out for variable attenuators, as well as for attenuators of fixed attenuation values as devices under test, which are fitted to quarter-wavelength lines in three different configurations, the attenuation is simply obtained and is unrelated to the source and load reflection coefficients of GammaG and GammaL, respectively. Experimental results on a 10-dB step attenuator measurement at frequencies from 1 to 17 GHz show good agreement with measurements where the source and load are impedance matched. The technique is effective even with GammaG and GammaL higher than 0.1.

Attenuation-Measurement Technique With a Small Mismatch Uncertainty Using Phase Characteristics of Multiple Reflected Signals

An accurate radio-frequency and microwave attenuation-measurement technique with a small mismatch uncertainty for continuous-frequency application has been developed by shifting the phase characteristics of the multiple reflected signals. A loss-measurement system in four different phase networks is set for this purpose by introducing two low-reflective lines (airlines) where the phase-shift values are already known. From substitution-loss measurements carried out for variable attenuators as devices under test, the attenuation is simply obtained, which is unrelated to the source and load reflection coefficients of ΓG and ΓL, respectively. Experimental measurements on a 10-dB step attenuator performed with a 40-mm length of airlines at almost continuous frequencies from 12.3 to 14.1 GHz are demonstrated and show a good agreement with measurements where the test ports are impedance-matched.

An automated 1-kHz null-balance receiver for precision RF and microwave attenuation measurements and standards

An automated 1-kHz null-balance receiver for the RF attenuation measurement system based on the dual-channel intermediate frequency substitution method was constructed and examined. A commercial programmable inductive voltage divider (IVD) was applied as its attenuation reference; however, highly accurate voltage ratios were ensured by the developed voltage ratio standard system. It is shown that the uncertainties caused by the imperfect voltage ratio of the IVD were less than 0.001 dB for attenuation measurements up to 60 dB. Comparison on attenuation measurements between the proposed automated receiver and the manual accurate one, were carried out in some microwave frequencies and good agreements were obtained.

Mismatch correction in RF attenuation measurement using precision airlines

The RF attenuation measurement technique with a small mismatch uncertainty [3] is improved to extend the frequency effectiveness. Three additional substitution loss measurements to the variable attenuator in different phases are realized by using precision airlines of arbitrary lengths where the phase shifts are known. As a result, attenuation measurements of arbitrary frequencies could be also obtained simply without source and load matched to the line impedance. Experimental results on a 10-dB and 20-dB at 11 GHz show good agreement with measurements where the source and load are matched.

A Consideration of Linearity in Heterodyne Detection

Linearity of heterodyne detection is important in intermediate frequency(IF) substitution method for radio frequency(RF) attenuation measurement. Basically, the conversion equation V=kappaE_s ^alpha (alpha=1, kappa=constant) is valid in a proper range of E_s where E_s and V are RF input and IF output amplitudes, respectively. This paper discusses the possibility that alphane1