Orthogonal Magnetic Components Research Articles

Electrically Small, Low-Q, Wide Beam-Width, Circularly Polarized, Hybrid Magnetic Dipole Antenna for RFID Application

A novel electrically small, wide beamwidth circularly polarized (CP) antenna using two orthogonal smaller hybrid magnetic dipoles (HMDs) for radio frequency identification (RFID) reader application is presented, which achieves a quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> -factor) approaching the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Chu-limit</i> . First, a HMD is implemented by the combination of two single-slit magnetic dipoles (S-MDs) and one dual-slit magnetic dipole (D-MD), which is carefully analyzed by equivalent circuit models and field distribution. Then, by implementing two orthogonal HMDs with slightly size difference and a 45° angle tilted coupling feeding line, two orthogonal magnetic components with equal magnitude and 90° phase difference are obtained, which lead to a CP radiation. Finally, an electrically small CP magnetic dipole antenna with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.12\,\,\lambda _{0} \times 0.12\,\,\lambda _{0} \times 0.04\,\,\lambda _{0} (ka&lt; 0.55)$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at its center frequency) is fabricated and measured. The measurement shows that a −10 dB impedance bandwidth of 3.17% (cover 902–928 MHz UHF band well), a half power beamwidth (HPBW) of 104°, and a peak radiation gain of 4.57 dBic are achieved. Generally, it features a small size, wide beamwidth, simple design, and good radiation performance, exhibiting good application potential usage in internet of things (IoTs) systems.

Measurements of the orthogonal magnetic components of the pulse component of infralow and very low electromagnetic fields at svalbard

A complex of equipment for recording three components Hx, Hy, and Hz of the pulse component of an electromagnetic field in the range of infralow-very low frequencies, which is incorporated in the geophysical observatory of the Polar Geophysical Institute (Barentzburg, Spitsbergen archipelago), is described. The complex operates under the control of the Linux operational system and is integrated in the local observatory computer network, thus providing both the remote access to data and the GPS time synchronization. The use of buffer transformers in both the signal circuit and the circuit for connection to the collective observatory supply line made it possible to improve the electromagnetic compatibility of this complex with the main instruments of the observatory. The technique for conducting the absolute calibration of the equipment is described.

Separation of the integrals of partially resolved doublets based on chemical shift evolution using non-selective RF pulses

New pulse schemes are presented for separation of integrals of partially resolved doublets using non-selective RF pulses. The separation is based on the evolution under the influence of chemical shift leading to two orthogonal magnetization components. The selection of one of these orthogonal signals is then achieved by retaining it in the transverse plane while converting the other into unobservable longitudinal magnetization. Alternatively, the desired signal is converted into longitudinal magnetization while the other signal is dephased using gradients. Subsequently, the longitudinal magnetization is converted to detectable signal. Experimental results are demonstrated, separately, using 1H and 13C NMR.

Asymmetry of magneto-optical Kerr effect loops of Co nano-columns grown by oblique incident angle deposition

Magneto-optical Kerr effect (MOKE) in the longitudinal mode was used to measure the in-plane magnetic anisotropy of about 300nm thick Co nano-column films that were grown by e-beam evaporation at different oblique incident angles (0–85°) on native SiO2 substrates at room temperature. The symmetry of MOKE loops measured at azimuthal angles that are 180° apart is obviously broken for Co nano-column films grown at high deposition angles >70°. The plot of coercivity Hc of loops versus azimuthal angle shows that Hc values for azimuthal angles between −90° and 90° are much larger than the values for azimuthal angles between 90° and 270°. The asymmetry of coercivity is due to MOKE measurement that combines both longitudinal and polar Kerr effects. This combination is caused by the oblique magnetic anisotropy associated with the tilted Co nano-columns. A method is introduced to separate the longitudinal and polar Kerr effects. The longitudinal Kerr effect is obtained by adding hysteresis loops measured at azimuthal angles 180° apart while the polar Kerr effect is obtained by subtracting these two loops. By comparing these two orthogonal magnetization components represented by longitudinal and polar Kerr effects, we show that magnetization rotation exists in the magnetic reversal process even at azimuthal angle φ=0° that is the closest in-plane direction to the easy axis. After separating these two Kerr effects, the two-fold symmetry of coervicity associated with tilted nano-columns measured by longitudinal Kerr effect is restored.

Simultaneous in-plane Kerr effects in Fe/GaAs (110) thin films

For many materials that can be magnetized, part of the magnetization process may be attributed to a rotation of the magnetization vector. In this context, a combination of the longitudinal and transverse magneto-optical Kerr effects are used to detect two orthogonal magnetization components in single-crystal Fe/GaAs (110) thin films. Hysteresis curves obtained by this magneto-optical technique are presented for fields along the in-plane [001], [11̄0], and [11̄1] crystal directions. For those curves that show signs of rotation, these data are simulated using a coherent rotation mechanism for the magnetization process and Fresnel reflection coefficients for the two Kerr effects. From the experimental data, it is found that the [11̄1] curves have shapes that are indicative of a rotational process. On the other hand, both the [001] and [11̄0] have magnetization curves that do not follow a simple rotation. From the coherent rotation model, there is qualitative agreement between the modeled and experimental data for the [11̄1].

Automatic AF demagnetiser for igneous rock specimens

A fully automatic 'magnetic cleaning' device suitable for demagnetisation of igneous rock specimens is described. The apparatus consists principally of a two-part solenoid energised through an autotransformer, a two-axis tumbler which is divisible into two parts, and an astatic magnetometer giving the three orthogonal magnetic components of the partially demagnetised rock samples.