Satoru Arakawa

Visualization of Poynting Vectors by Using Electro-Optic Probes for Electromagnetic Fields

We visualized electromagnetic-energy flows by using newly developed electro-optic probes, which cause little interference with the surrounding electromagnetic fields. Amplitudes and phases of all electric- and magnetic-field components were measured near a coupled line and a patch antenna by the probes. The time-varying Poynting vectors near the objects were evaluated with the data and were visualized. The energy flows that are caused by crosstalk of the coupled line and that are radiated from the antenna are presented. This is the first visualization of Poynting vectors that are evaluated with only experimental data in near-field regions.

Optical magnetic field probe with a loop antenna element doubly loaded with electrooptic crystals

We propose a new type of optical probe designed to detect magnetic near-fields with high accuracy up to the gigahertz range. Its probe head consists of a loop antenna element doubly loaded with electrooptic crystals. Using optical technology, it realizes hybrid operation of a conventional double-loaded loop probe and requires no metallic cables or electrical hybrid junction. We examined probe characteristics for magnetic field detection up to 10 GHz. We confirmed that the probe can measure magnetic fields near a microstrip line with high accuracy in the gigahertz range and can suppress influence of electric fields.

High speed system for measuring electromagnetic field distribution

An optically scanning electromagnetic field probe system consisting of an electro-optic or magneto-optic crystal and a galvano scanner is proposed for high-speed electromagnetic field distribution measurements. We used this technique to measure electromagnetic field distributions near printed circuit boards or ICs to address electromagnetic compatibility problems or in designing electronic devices. With our scanning system, we can measure the electric field intensities of about 40,000 points with an area of 40 x 40 mm in about 3 minutes (4 ms per point) up to 2.7 GHz. We measured the electric near-field distribution above a five-split transmission line using a cadmium telluride (CdTe) electro-optic crystal. The measurement results showed that the spatial resolution of the system was less than 400 μm in the case of a common current with a crystal thickness of 1 mm. The electric near-field distribution above a microstrip line filter was measured using LiNbΟ 3 electro-optic crystal. Changes in the distribution according to the frequency were observed. The experimental results obtained using this system were compared with simulation results obtained using a finite-difference time-domain method. The overall results indicated that the measurement system is capable of accurately measuring electric near-fields. We also discuss the invasiveness of the measurement system, due to the electro-optic crystals, in terms of both the experimental and simulated results.

Optical magnetic field probe working up to 15 GHz using CdTe electrooptic Crystals

This paper presents a new type of optical magnetic field probe designed to detect magnetic near-fields with high accuracy up to 15 GHz. The probe head consists of a loop antenna element and CdTe electrooptic crystals. The probe using CdTe has a resonant frequency higher than that of a previous probe using LiNbO/sub 3/ because CdTe has a dielectric constant lower than that of LiNbO/sub 3/. Through an optical technique, a probe doubly loaded with CdTe can work as a conventional double-loaded loop probe without metallic cables or an electrical hybrid junction. We examined probe characteristics up to 20 GHz. We confirmed that the probe could measure magnetic fields near a microstrip line with high accuracy in the gigahertz range.

EO probe for simultaneous electric and magnetic near-field measurements using LiNbO/sub 3/ with inverted domain

This paper presents a new type of optical probe for simultaneous measurements of electric and magnetic near fields with high accuracy up to the gigahertz range. Its probe head consists of a loop antenna element that is doubly loaded with LiNbO3 electrooptic crystals. Using optical technology, it can work as a conventional double-loaded loop probe without metallic cables and electrical hybrid junction. We examined probe characteristics for electromagnetic field detection up to 20 GHz. We confirmed that the probe can measure electric and magnetic fields simultaneously with a high accuracy in the gigahertz range

Invasiveness of an Optical Magnetic Field Probe

Electromagnetic field probes inevitably disturb the original distribution of the field when they are positioned close to a device. This disturbance in turn affects measurement accuracy and device operation. We developed an optical magnetic field probe, comprising a loop antenna element and an electro-optic crystal, for highly accurate magnetic near-field measurement in the GHz frequency range. We analyzed the invasiveness of the optical magnetic field probe quantitatively both experimentally and using finite difference time domain simulation. We found that eliminating the metal cable reduced the disturbance of the surrounding field that was to be measured. In addition, we investigated the magnetic field detection characteristics of the probe and its influence on the operation of a microstrip line. The optical magnetic field probe was less invasive and provided more accurate measurement.