Eiji Hankui

Time-domain magnetic field waveform measurement near printed circuit boards

This paper describes a time domain magnetic field measurement process for measuring magnetic fields near printed circuit boards (PCBs) with a loop probe. In carrying out these measurements, the loop probe needs to be calibrated in the frequency domain. In this process, a microstrip line with a teflon substrate serving as the standard magnetic field source is employed as a means of calibrating the probe. The standard magnetic field intensities of the line are calculated by using an approximate equation obtained from Amperes law to simplify the calibration. The sensor-factor of the probe obtained from this method agrees with that obtained through the use of a standard G-TEM cell in 2 dB at frequencies below 1 GHz. The waveforms of magnetic fields near a PCB having a four-layer construction are measured using a 10 mm diameter loop probe as the calibrated magnetic field sensor. The generation of magnetic field waveforms causing the radiated emission from the PCB is found to depend on the circuit operating conditions. Our results clarify the fact that the time domain magnetic field measurement process is an effective tool for analyzing the sources of emission radiated from PCBs and for investigating the radiation mechanism.

Compact and Multiband Electromagnetic Bandgap Structures With Adjustable Bandgaps Derived From Branched Open-Circuit Lines

Branched open-circuit lines are introduced for artificial negative-permittivity media, which is a type of metamaterial, to simultaneously achieve compact unit cells and adjustable bandgaps to cover multiband frequencies. Our electromagnetic bandgap (EBG) structures, the unit cells of which are under

Compact antenna using split-ring resonator integrated with bent dipole-like metal pattern

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Band-Selectively Tunable Electromagnetic Bandgap Structures With Open-Circuit Lines and Variable Capacitors

of the wavelength in a substrate, were designed to display characteristic effects, including bandgap-separation control and enhancement of the bandgap width. We analytically and experimentally investigated these effects. The compactness is derived from the length-dependent resonances of the open-circuit line instead of inductance-capacitance resonances, and the adjustable bandgaps originate from the introduction of the branched shape, which destroys the periodic capactive-inductive-impedance alternation of not-branched open-circuit lines. The proposed EBG structures are highly promising for frequency-selective devices, such as for electromagnetic noise suppression in power distribution networks.

LTE throughput evaluation of MIMO antenna handset in the presence of user's body

We propose a novel compact antenna using a split-ring resonator (SRR), a common metamaterial structure. By integrating an SRR with a bent dipole-like metal pattern, miniaturization and performance enhancement are achieved. From simulated results, we confirm wide bandwidth and high efficiency close to the theoretical limit. We also designed and evaluated the proposed antenna with a reflector and extended feed line for applications requiring directed radiation.

Printed circuit board design support system, printed circuit board design method and storage medium storing control program for same

We discuss the band-selective tuning of specific bandgaps (BGs) in an electromagnetic BG (EBG) structure. Two variable capacitors (VCs) attached to an open-circuit line (an element of the EBG structure) are selectively excited by voltage standing waves in the open-circuit line, and they can selectively tune the first and second BGs. With the change in a VC by 4.8 pF, the first BG moves from 0.55 to 0.39 GHz with almost no shift of the second one, while the second BG is tuned from 1.61 to 1.29 GHz with a 1.8-pF change in the other VC. This tuning technique can be potentially applied to other microwave devices using resonant phenomena such as antennas and filters.

Compact cellular phone

This paper evaluates LTE throughput of MIMO antenna handset by a system level simulator. Especially, MIMO antenna configuration impact on throughput performance is investigated when a user holds the handset with either left or right hand. By analyzing throughput on some antenna configurations, we find that throughput mainly depends on received channel power changing by users hand effect. Therefore, MIMO antenna elements should be separated each other as far as possible, and avoid being covered by users hand simultaneously. Moreover, we confirm that correlation and power imbalance impact on throughput cannot also be ignored in designing MIMO antenna.