Circumference-length dependency of the wireless power transmission (WPT) performance between the circuit-shape leaky waveguide and a $\lambda/2$ wavelength dipole antenna was analyzed by utilizing the FDTD method. The proposed waveguide was composed of a pair of straight waveguides with slot openings and a pair of semicircular waveguides to effectively melt snow with microwave radiation [1] with reducing heavy snow removal workloads [2]. The WPT efficiencies between the waveguide and the $\lambda/2$ dipole antenna located 30-mm above the waveguide with parameterized circumference length were calculated from the S-parameters [3] by the FDTD method.
Multi-band and wideband planar antennas are strongly desired for recent wireless applications. Microstrip antennas (MSAs) are attracted by various wireless applications due to the practical advantages of small size, low profile, light weight, and low-cost manufacturing. The authors have developed multi-ring microstrip antennas (MR-MSAs) as multiband planar antennas [1]. The MR-MSA consists of multiple ring patches arranged concentrically and an L-shaped feeding probe (L-probe) with a double-layered dielectric substrate. The MR-MSA exhibits flexible multiband design capability because the resonant frequencies can be tuned flexibly and because stable unidirectional radiation patterns are obtained. Furthermore, linear and circular polarizations can be also designed individually at the resonant frequencies. However, bandwidths of the MR-MSA become narrow when a thin dielectric substrate is used. In order to solve this problem, the authors have presented single- and dual-band MR-MSAs fed by an L-probe with a thick dielectric substrate for wideband operation [2]. The single-band and wideband ring MSA provides approximately 45% fractional reflection bandwidth of below −10 dB reflection, where a thick double-layered dielectric substrate with a thickness of approximately 0.15 wavelengths at the center frequency is used. On the other hand, a single-layer wideband ring MSA fed by an L-probe have been proposed [3]. A split ring patch and an L-probe are arranged in the same layer of a thick substrate with a thickness of approximately 0.12 wavelengths at the center frequency and approximately 30% fractional reflection bandwidth is obtained.
The Meta-surface inspired Antenna Chip developed by KIT EOE Laboratory (MACKEY) [1] is an antenna designed using the AMC technology. It is an electrically small antenna that is sufficiently robust to metal objects. Circularly polarized MACKEYs with two or four feed points have been reported [2] [3]. In this presentation, a circularly polarized MACKEY with single port named MACKEY C4F1 will be proposed.
Increasing demands on high-performance platforms in the sixth generation (6G) of mobile communications raise research focus on new transducers that can address both the coverage and power issues. One of the key technologies recently adopted to design and implement such promising features is metasurface (MTS). MTSs are two-dimensional low profile artificial materials realized by electrically small meta cells. Providing particular impedance boundary conditions (BC), they have a variety of applications that extensively increased their usage during the last decade. The need for reconfigurability and having a dynamic electromagnetic response resulted in introducing the reconfigurable intelligent surfaces (RISs) as one of the new popular MTSs in recent years [1].
Device-Free Localization (DFL) employs passive radio techniques capable to detect and locate people without imposing them to wear any electronic device. By exploiting the Integrated Sensing and Communication paradigm, DFL networks employ Radio Frequency (RF) nodes to measure the excess attenuation introduced by the subjects (i.e., human bodies) moving inside the monitored area, and to estimate their positions and movements. Physical, statistical, and ElectroMagnetic (EM) models have been proposed in the literature to estimate the body positions according to the RF signals collected by the nodes. These body models usually employ a single-antenna processing for localization purposes. However, the availability of low-cost multi-antenna devices such as those used for WLAN (Wireless Local Area Network) applications and the timely development of array-based body models, allow us to employ array-based processing techniques in DFL networks. By exploiting a suitable array-capable EM body model, this paper proposes an array-based framework to improve people sensing and localization. In particular, some simulations are proposed and discussed to compare the model results in both single- and multi-antenna scenarios. The proposed framework paves the way for a wider use of multi-antenna devices (e.g., those employed in current IEEE 802.11ac/ax/be and forthcoming IEEE 802.11be networks) and novel beamforming algorithms for DFL scenarios.
