Characteristic analysis of a wideband balun transformer having a delay line element for phase compensation

The balanced‐unbalanced transformer (balun) is extensively used in radio communication and measuring instruments. In recent years, with the development of television and portable telephones, wideband transformers tend to be miniaturized. In this paper, the wideband transformer is analyzed in terms of distributed coupled‐line theory. A main result of the analysis is that the balance and unbalance transmission characteristics of the balun are markedly improved in the high‐frequency range by using a delay line element for compensation. If the connection point S_w between the coil winding and delay line is off the ground, the balance transmission band is about doubled in the low‐frequency range. If the point S_wis grounded and if the impedance ratio m² is small, a higher degree of unbalance attenuation can be obtained. Better balance transmission characteristics can be obtained when the matching factor K approaches half the optimum. In addition, we show that an in‐phase or anti‐phase transformer can be made on the basis of our isolation wideband transformer. The equivalent circuits of in‐phase and anti‐phase wideband n:1 transformers are obtained from our theoretical analysis and these can be formed by the same transformer. The transmission characteristics of in‐phase and anti‐phase wideband transformers are analyzed and improved characteristics are obtained in the high‐frequency range. The theoretical and experimental values agree well over the wide frequency range of 100 KHz to 1000 MHz. ©1998 Scripta Technica, Electr Eng Jpn, 126(2): 1–14, 1999     

Depletion of Monolayer Liquid Lubricant Films Induced by Laser Heating in Thermally Assisted Magnetic Recording

The white layer (WL) generally refers to an untempered martensite layer generated by severe sliding conditions, such as cutting, drilling, grinding, milling, and electron-discharge machining. Numerous tribologists have investigated the effect of the WL on wear behavior, but this phenomenon is not yet clearly understood because no attempt has been made to correlate the wear mechanism of the WL with its wear behavior. It is necessary to investigate the effects of the WL on wear comprehensively. Therefore, elasto-plastic properties, wear resistance, and wear mechanism of WL were studied with nanoindentation and wear tests. The results of this study show that the elastic moduli, yield strength, and hardness of the WL increased by approximately 170, 390, and 180%, respectively. Thus, it was found that the WL had distinct properties with respect to the substrate of AISI 52100 steel. It is possible that the increased surface hardness is an advantage in terms of wear resistance. However, the advantage diminishes, and the WL is subject to wear when delamination dominates the wear mechanism.     

Low‐cost laser disdrometer with the capability of hydrometeor imaging

Precision of microwave precipitation remote sensing is ensured by studying different hydrometeor classes (raindrops, snowflakes, graupel, and so on), shapes, and drop size distribution (DSD). Recently, DSD estimates and hydrometeor classification algorithms using polarimetric radars were proposed. These algorithm developments require a validation tool providing in situ hydrometeor measurement. We are working toward the development of a low‐cost, light‐weight, and disposable ballooning hydrometeor imaging probe with DSD measurement capabilities. This paper describes the performance of a new line‐scanning laser hydrometeor imaging probe (called PROBE) and validates the DSD using a commercially available impact‐type disdrometer. PROBE captures raindrop images with 0.125 mm horizontal resolution and more than six slices at the 33‐kHz slice rate, providing a reasonable raindrop diameter. DSD validation shows that PROBE acquires adequate DSD shapes during every 2‐min interval. These results demonstrate PROBE's performance in hydrometeor imaging and DSD measurement capabilities in a rainfall. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Control of head smear generation by diamond-like carbon films using an external electric field

Microsystem Technologies - The formation of head smears in heat-assisted magnetic recording is a significant problem that must be addressed to ensure the reliability of the head-disk interface. In...