소형 안테나 ( Small Antennas )

Background and History. Resonator and Filter Topologies. Baw Device Basics. Design and Fabrication of BAW Devices. FBAR Resonators and Filters. Comparison with SAW Devices. Films Deposition for BAW Devices. Characterization of BAW Devices. Monolithic Integration. System-in-Package (SiP) Integration. Index.

RF bulk acoustic wave filters for communications

We report the first experimental generation of high-order Mathieu beams and confirm their propagation invariance over a limited range. In our experiment we use a computer-generated phase hologram. The peculiar behaviour of the vortices in Mathieu beams gives rise to questions about their orbital-angular-momentum content, which we calculate by performing a decomposition in terms of Bessel beams.

Holographic generation and orbital angular momentum of high-order Mathieu beams : Special issue on atoms and angular momentum of light

Recently, orbital angular momentum (OAM) based vorticose communication has attracted much attention because of its potential to significantly increase the spectrum efficiency (SE) of wireless communications. However, the multiple radio frequency (RF) chains used for multiple OAM modes lead to an unexpected cost for wireless vorticose communications. In this paper, we first propose the mode modulation (MM) based OAM system to allow multiple OAM modes sharing a common RF chain. The proposed MM cannot only reduce the hardware cost, but also boost the SE by introducing the mode as an additional dimension for data transmission. Moreover, without the channel state information (CSI) feedback, we develop an equal-probability mode modulation (EMM) scheme to maximize the SE of MM-based OAM systems with the limited RF chains. In addition, with the CSI feedback, we develop a Huffman coding based adaptive mode modulation (AMM) scheme, which can adaptively choose the OAM modes to further increase the SEs of OAM-based wireless communications. We also develop the joint power and probability allocation policy for the AMM scheme to achieve the maximum SEs for OAM-based vorticose communications. Numerical results demonstrate that the MM can offer a new mode dimension for vorticose communications and the AMM scheme can achieve larger SE than the EMM scheme.

Mode Modulation for Wireless Communications With a Twist

Electromagnetic (EM) waves with helical wavefront carry orbital angular momentum (OAM), which is associated with the azimuthal phase of the complex electric field. OAM is a new degree of freedom in EM waves and is promising for channel multiplexing in communication system. Although the OAM-carrying EM wave attracts more and more attention, the method of OAM generation at microwave frequencies still faces challenges, such as efficiency and simulation time. In this work, by using the circuit theory and equivalence principle, we build two simplified models, one for a single scatter and one for the whole metasurface to predict their EM responses. Both of the models significantly simplify the design procedure and reduce the simulation time. In this paper, we propose an ultrathin complementary metasurface that converts a left-handed (right-handed) circularly polarized plane wave without OAM to a right-handed (left-handed) circularly polarized wave with OAM of arbitrary orders and a high transmission efficiency can be achieved.

Ultrathin Complementary Metasurface for Orbital Angular Momentum Generation at Microwave Frequencies

Mental activity classification (MAC) based on electroencephalogram (EEG) is used in the brain–computer interface (BCI) and neurofeedback applications. For this purpose, machine learning and deep learning (DL) techniques are utilized in the previous studies. However, in real time, there is a need to deploy these techniques on Internet of Things (IoT)-enabled mobile devices for portability. Toward this aspect, we propose DL-based MAC using a depthwise separable convolutional neural network with a custom attention unit (DSCNN-CAU) and IoT implementation using a smartphone for portable BCI applications. The performance assessment on EEG signals from two public and two self-acquired databases demonstrates that the overall accuracies of 99.25%, 95.00%, and 91.50%, 89.25% are obtained, respectively. Evaluation results on smartphone depict that most of the real-time recorded EEG signals in self-acquired databases are classified correctly. Further comparative analysis demonstrates that the proposed model and the IoT implementation outperform the existing techniques in terms of accuracy, robustness against artifacts, latency, and battery current dissipation. A total current of 21 mAh is dissipated in EEG signal recording, processing, and event-based transmission to the server, and low latency of 71 ms is achieved in MAC. Further analysis of cross-database performance enables the selection of the $F_{P1}$ channel for real-time MAC in IoT-based scenarios.

DSCNN-CAU: Deep-Learning-Based Mental Activity Classification for IoT Implementation Toward Portable BCI

Radio Frequency (RF) Microelectromechanical system (MEMS) switches are becoming more and more popular in the electronics industry. The main concern in using RF MEMS switch is its high actuation voltage. Thus the main focus in this paper is to obtain low actuation voltage. This paper presents the simulation and analysis of RF MEMS cantilever beam and Fixed – Fixed beam switches. RF MEMS switches simulated in this paper use electrostatic actuation method. Simulations were done using finite element modeling. Different designs and parameters such as gap between electrodes, beam thickness, beam length, and relative permittivity values of medium between electrodes were chosen for analyzing the deflection of beams for various actuation voltages. Perforations of different dimensions were made on both type of beams and the resulted deflections were studied. The simulation results show that the Cantilever and Fixed – Fixed beams follow approximately similar deflection pattern with Cantilever beam deflecting more for applied actuation voltage in all the studies.

Simulation and Analysis of Actuation Voltage of Electrostatically Actuated RF MEMS Cantilever and Fixed – Fixed Switches with Variable Beam Parameters

In this paper a dual band butterfly shaped planar antenna is proposed. The structure consist of two trapezoid located symmetrically to the y axis. An inductive stub is used for impedance matching. The measured antenna resonates at 2.9GHz and 5.32 GHz with impedance bandwidth of 63.6 MHz, 188.7MHz respectively. The measured gain of the proposed antenna is 2.5dBi at 2.9 GHz and 5.5dBi at 5.32GHz.

Dual Band Butterfly Planar Antenna for WLAN Applications

In this paper, An electronically tuned circular patch antenna with good radiation pattern is proposed and studies. patch antenna has been designed with predicted obtainable tuning range. Electronic tunablity is achieved by connecting Varactor diodes thus altering the capacitance of the patch and hence resonant frequency. Although this antenna has a low bandwidth, electronic tuning allow a large band to covered with maintaining the same narrow band operational characteristics. RT-Duroid 5880 substrate (∊ г = 2.3) with thickness of 0.8 mm used in this design. Proposed antenna performance is evaluated by compairing results.

Study of electronically tunable circular patch antenna

The present work focusses on the design and simulation of a thin film bulk acoustic resonator (TFBAR) and a polyimide based TFBAR (PI-TFBAR) and compares the radio frequency (RF) bandpass filter response designed from these resonators. The Polyimide layer in the PI-TFBAR acts as an acoustic wave reflector along with providing mechanical strength to the device. The designed third order bandpass filter has a ladder topology. The insertion loss of the TFBAR filter is 1.69 dB and the return loss is 39.60 dB whereas the insertion loss and return loss are 1.71 and 23.7 dB respectively for the PI-TFBAR filter. The bandwidth of the TFBAR filter is 68.0 MHz and for PI-TFBAR it is 25 MHz. The proposed filter designs, with further optimization, may have application in the 2.6 GHz band, which has been identified by the International Telecommunication Union as a global band for International Mobile Telecommunications and is one of the core bands of LTE-Advanced technology.

Madhur Deo Upadhayay

Papers

DSCNN-CAU: Deep-Learning-Based Mental Activity Classification for IoT Implementation Toward Portable BCI

Simulation and Analysis of Actuation Voltage of Electrostatically Actuated RF MEMS Cantilever and Fixed – Fixed Switches with Variable Beam Parameters

Dual Band Butterfly Planar Antenna for WLAN Applications

Study of electronically tunable circular patch antenna

A comparative study on the design and simulation of TFBAR and polyimide-TFBAR based RF bandpass filters