Farid Jolani

COMPACT M-SLOT FOLDED PATCH ANTENNA FOR WLAN

This paper presents a very small size microstrip antenna suitable for WLAN application. The main patch antenna consists of an M-shaped slot with shorting wall. With a shorted triangular parasitic patch and a folded patch overall antenna size is reduced. The simulated and measured results show that by selecting a proper shorting wall width, the proposed antenna can provide an impedance bandwidth of 21.17% covering the 4.93–6.09 GHz band. The antenna size is of order 0.1094λo × 0.1094λo × 0.0544λo (6 × 6 × 3 mm3). The proposed antenna has 75% surface size reduction compared to a conventional patch antenna operating at the same centre frequency. The Eand H-plane radiation pattern across the entire operating bandwidth is provided.

A Wideband Omnidirectional Horizontally Polarized Antenna for 4G LTE Applications

An innovative wideband omnidirectional horizontally polarized (HP) antenna is presented for 4G Long Term Evolution (LTE) wireless communication and networking systems. The proposed planar antenna consists of four pairs of flag-shaped radiators, a balun for balance-unbalance transformation, and four parasitical strips for bandwidth enhancement. Such a design enables in-phase and axially symmetric current flowing along the radiators. The measurements show that the proposed HP antenna exhibits a relative bandwidth of 41% with the return loss greater than or equal to 10 dB; it covers the frequency band of 1.76-2.68 GHz, including PCS, UMTS/LTE, Bluetooth, ISM, and WLAN bands. With an omnidirectional radiation pattern in E-plane, the proposed antenna has a peak gain of 3.6-4.2 dBi across the operational band and a radiation efficiency of 83%. The low profile and compact design, along with the omnidirectional radiation pattern, makes it ideal for ceiling or surface-mounted indoor and automobile 4G applications.

A Planar Magnetically Coupled Resonant Wireless Power Transfer System Using Printed Spiral Coils

A fully planar wireless power transfer (WPT) system via strongly coupled magnetic resonances is presented. In it, both the transmitter and the receiver are planarized with the use of coplanar printed spiral coils (PSCs) and a printed loop. An equivalent circuit model of the proposed planar WPT system is derived to facilitate the design, and a flowchart is provided for the optimization of the system with given size constraints. To realize high peak power transfer efficiency, the quality factor of individual loop or resonator, the mutual coupling between resonators, and the frequency splitting phenomenon of the system are analyzed in addition to the effect of the input impedance of the system on the transmission efficiency. Furthermore, parallel current paths are created by applying auxiliary strips to the backside of the substrates and connecting to the prime resonators using vias to decrease the resistance and to increase the quality factor of the PSC resonators, and this in turn further improves the transfer efficiency of the proposed planar WPT system. The measured results show that the proposed WPT system is able to provide a stable wireless power transfer with up to 81.68% efficiency at a distance of 10 cm. The planar structure and the high transfer efficiency make the proposed design a suitable candidate for wireless power transfer of small portable electronic devices.

DESIGN AND OPTIMIZATION OF COMPACT BALANCED ANTIPODAL VIVALDI ANTENNA

In this paper, the conformal finite-difference time-domain (CFDTD) method using PSO optimization is applied to design a compact directive balanced antipodal Vivaldi antenna for ultrawideband (UWB) applications. This paper demonstrates miniaturized antipodal Vivaldi antenna (32 × 35 × 1.6mm3), having low-cross polarization levels and reasonable gain from 3.1 to 10.6 GHz. The antenna peak gain is 5.25 dBi in the specified band. The simulated and experimental results of return loss, far field patterns and gain are presented.

Planar Multiband Antenna for Compact Mobile Transceivers

A compact planar antenna for portable multistandard transceivers is presented. The proposed microstrip-fed antenna includes a symmetrical double G-shaped radiator and slotted ground plane. A return loss of better than 10 dB is achieved at the frequency bands PCS (1850-1990 MHz), WLAN+ Bluetooth (2400-2480 MHz), WiMAX (2500-2690 MHz), WiMAX (3400-3600 MHz), HIPERLAN2 (5150-5350/5470-5725 MHz), and IEEE 802.11a (5150-5350-5725-5825 MHz). Moreover, the return loss is more than 6 dB across the DCS band (1.71-1.88 GHz). The proposed antenna is printed on a single-layered FR4 substrate, and it occupies a small volume of 40 × 30 × 1.6 mm3. The simulated and measured performance of the antenna confirms its multiband operation and omnidirectional radiation pattern.

COMPACT ULTRA-WIDEBAND PHASE SHIFTER

Design of a compact planar phase shifter is described that possesses ultra-wideband (UWB) performance. The proposed device is composed of 50› input/output microstrip-lines which are connected to a low-impedance rectangular microstrip patch, and located at close proximity to each other. The common ground-plane incorporates a

PSO/FDTD Optimization Technique for Designing UWB In-Phase Power Divider for Linear Array Antenna Application

This letter presents the design of a compact planar in-phase power divider with ultrawideband (UWB) performance. The device consists of three T-shaped microstrip lines arranged in parallel to each other on one side of the dielectric substrate that are electromagnetically coupled with an H-shaped slot etched on its ground plane. Particle swarm optimization (PSO) and the finite-difference time domain (FDTD) are combined to achieve the optimal power divider design for a given specification. The measured results show the transition of the signal between the T-shaped microstrip line and the ground-plane slot divides power equally, with relatively low insertion loss, good return loss, high stability of phase, and high isolation between the two output ports across the UWB frequency band defined between 3.1-10.6 GHz. The power divider is compact in size, occupying an area of 15 × 32 mm2. These features make it suitable for linear array antennas.

Efficient Modeling of Open Structures Using Nonuniform Leapfrog ADI-FDTD

The perfectly matched layer (PML) using the split-field formulation has been implemented in a recently developed leapfrog alternating-direction-implicit finite-difference time-domain method (leapfrog ADI-FDTD) for efficient modeling of open structures. To further enhance computational efficiency and modeling accuracy, a nonuniform numerical grid is incorporated in the proposed formulations. Numerical simulations of a 2-D TE wave in an open region and an electromagnetic band-gap Y-power splitter are performed to verify the implementation with the PML. The results show that with the proposed method, CPU time savings can be up to 50% of that of a conventional ADI-FDTD.

A planar magnetically-coupled resonant wireless power transfer using array of resonators for efficiency enhancement

A novel magnetically-coupled resonant wireless power transfer (MCR-WPT) system using an array of printed spiral resonators is presented. By replacing the single transmitting resonator in a conventional MCR-WPT with an array of smaller resonators, the transfer efficiency of the planar WPT system in both the over-coupled and under-coupled regions are significantly enhanced. Furthermore, with a proper design of the driving loop, the proposed WPT is able to provide consistent transfer efficiency even when the receiver is axially misaligned with the transmitter. Two WPT systems of the size of 10×21 mm2 and 21×21 mm2 for the transmitter, and 10×10 mm2 for the receiver are proposed. The results are compared with the conventional planar WPT of the same size. The measurement results show that with the proposed design, the transfer efficiency of the planar WPT system can be increased from 5% to 66% in the over-coupled region and from 0.75% to 40.67% in misalignment region.

A novel broadband omnidirectional dual polarized MIMO antenna for 4G LTE applications

A low-profile broadband omnidirectional multiple-input and multiple-output (MIMO) antenna with dual polarization is presented, which provides polarization diversity for the 4G Long Term Evolution (LTE) communication systems, networks, and base stations. It consists of two orthogonally polarized radiating elements with separate feeds. The horizontally-polarized element is comprised of four pairs of flag-shaped dipoles, four parasitical strips, and a balun with tapered striplines for balance-unbalance transition. It has a fractional bandwidth of 55% covering from 1.7 GHz to 3.0 GHz with return loss greater than 10 dB and an overall size of 43×43×1.6 mm3. The vertically polarized element consists of a discone antenna, a round sleeve, and a top-loading ring shorted to the ground-plane for bandwidth enhancement. It has a fractional bandwidth of 137% covering from 671 MHz to 3580 MHz, and an overall volume of 170×170×56 mm3. The measurement results show both antenna elements exhibit smooth gain over the operational bandwidth. In addition, the geometrical shape and compactness of the proposed design, along with the omnidirectional radiation patterns, makes it ideal for ceiling or surface-mounted 4G LTE applications.