Three-dimensional sensing of the magnetic-field vector by a compact planar-type Hall device

Smart society is forthcoming with a rapid development in the automation of electric appliances requiring abundant sensors. One of the key sensors is a three-dimensional magnetometer for detecting the motion of objects, which is usually driven by cooperative multiple sensors on three orthogonal planes. Here, we demonstrate the fundamental operation of a three-dimensional magnetometer based on a simple Fe-Sn heterostructure Hall device in a planar geometry. Polar coordinates of the magnetic-field vector are uniquely determined by the combination of the sizable anomalous Hall effect, the anisotropic magnetoresistance, and the unidirectional magnetoresistance. Thanks to the ferromagnetic topological features in the Fe-Sn heterostructure, the above-mentioned device overcomes the limitation of conventional semiconductor devices and is highly sensitive even at room temperature. The compact planar geometry will be particularly useful in versatile electrical applications requiring a low-cost three-dimensional magnetometer with space- and energy-saving features.

A Compact Fractal-Shaped O-Ring Monopole Antenna for Modern Broadband Wireless Applications

In this letter, the design of a compact planar Fractal-shaped O-ring monopole antenna based on the Sierpinski carpet concept is studied and proposed for modern broadband wireless applications. The planar fractal-shaped O-ring monopole antenna is on the basis of Sierpinski category construction and then modifies the state of the plane inward with a radius of 27mm over the two iterations. The antenna structure is low profile and easy to be fabricated, and it has performed the simulation and measurement with the result VSWR ≤ 2 that can achieve a wide impedance bandwidth 636% from the frequency band 1.57GHz ~ 10GHz. The geometric scale factor of the Sierpinski fractal is according to the same scale element that defines the geometrical self-similarity. In our experiments, the results show that use of fractal-shaped O-ring into monopole antenna structure can effectively improve input impedance matching, and obtain a larger bandwidth and better radiation pattern, while also having predictable multi-band characteristics.

A Compact Planar Dual-Band Multiple-Input and Multiple-Output Antenna with High Isolation for 5G and 4G Applications

In this paper, a compact planar dual-band multiple-input and multiple-output (MIMO) antenna with high isolation is presented to satisfy the increasing requirements of wireless communication. The proposed antenna array consists of two identical radiating elements which are fed through micro-strip lines. A rectangular micro-strip stub with defected ground plane is employed to achieve a high isolation which is less than −15 dB between the two antenna elements. The size of the entire MIMO antenna is 32 × 32 × 1.59 mm3, which is printed on an FR4 substrate. The proposed MIMO antenna is optimized to operate in 2.36–2.59 GHz and 3.17–3.77 GHz bands, which can cover the fifth-generation (5G) n7 (2.5–2.57 GHz) and the fourth-generation (4G) Long Term Evolution (LTE) band 42 (3.4–3.6 GHz). The proposed MIMO antenna is feasible for the 5G and 4G applications.