Jui-Hung Chou

All Polarization Receiving Rectenna With Harmonic Rejection Property for Wireless Power Transmission

In this paper, a high conversion efficiency rectenna for wireless power transmission at 2.45 GHz is proposed. The rectenna is fabricated on a low-cost FR-4 substrate. The proposed design contains a dual circularly polarized patch antenna in which a high-order harmonic rejection property is embedded, and a pair of rectifying circuits without harmonic rejection filters. The dimension for the proposed rectenna design is 100×100×3.8 mm3. The proposed rectenna collects waves in all polarization senses simultaneously with a suitable air gap width, chosen to maximize antenna gain, and provide high isolation between the rectifying circuits. The rectifying circuits are fed by the wave power of orthogonally polarized waves. The conversion efficiency is improved by blocking the second and the third harmonic noise from reemission without suffering loss from filters: the second harmonic noise is rejected with a T-shape slot, while the third is rejected by a U-shape resonator. The measured conversion efficiency of the proposed rectenna reaches 82.3% when the inputs of the rectifying circuits are fed at 22 dBm, surpassing the majority of existing rectenna designs in the current literature. The functionality of reception at all polarizations is also verified, distinguishing our design from other proposals.

A Compact Loop-Slot Mode Combination Antenna for Ultra-Thin Tablet Computer With Metallic Bottom Cover

A novel compact dual-band loop-slot combination antenna for use in wireless local area network (WLAN) applications is proposed. The radiation mechanism is based on two resonant structure types, metal loop and slotline, combined into a single antenna to achieve WLAN 2.4 (2.4 ~ 2.484 GHz) and 5 GHz (5.15 ~ 5.85 GHz) operation. The proposed antenna is implemented in an ultra-thin tablet computer of dimensions 241×183×6.5 mm3, with a fully metallic cover on the bottom. The size of the proposed antenna is only 21×7.5×4.5 mm3 with a metal bottom cover below and an LCD panel nearby. The reflection coefficient measured from the antenna demonstrates that the operation bandwidth is 140 and 1300 MHz using a -10-dB definition in WLAN 2.4 and 5-GHz bands, respectively. In addition, good radiation performance is also achieved.

Novel UHF RFID Loop Antenna with Interdigital Coupled Section on Metallic Objects

A small-size printed loop antenna operated at its half guided wavelength (λg /2) mode as the fundamental resonant mode for achieving operation in Taiwan RFID UHF band is presented. The proposed antenna consists of a half guided wavelength loop antenna, inter-digital coupling section and a small U-shaped strip inductance structure. The proposed antenna has a simple structure of comprising shorting via of length about 118 mm to cover the Taiwan RFID UHF bands. Further, the antenna has a simple planar structure and occupies a small area of 30 × 40 mm2 on the system circuit board of the metallic object. This proposed antenna with good matched impedance, compact size, and measured maximum reading range in free-space is about 7.2 m, which can be suitable for RFID applications. Details of the proposed loop are discussed in this paper.

A Novel Miniaturized Dual-Layered LTE Printed Antenna for Handheld Devices

In this letter, a novel miniaturized multilayer internally printed antenna combined with two FR4 materials for triple Long Term Evolution (LTE) band operation is proposed. The proposed antenna is designed using a capacitive feed structure and an orthogonal meander line at the top edge of a subsection of the complete structure with dimensions of only 14 × 15 × 3.2 mm3. This covers triple-band operation (LTE700, LTE2300, and LTE2500). The complete dimensions of the mobile device are 50 × 100 mm2. The reflection coefficient is measured and used to demonstrate that the operation bandwidth is 42 MHz in LTE700 operation by a 3:1 VSWR. It is also suited to two full-band operations (LTE2300 and LTE2500) by using the definition of the -10-dB reflection coefficient in two higher modes of operation.

A Compact Dual-Band Printed Antenna Design for LTE Operation in Handheld Device Applications

A novel internal printed antenna suitable for triple long-term evolution (LTE) bands for handheld devices is presented. The operating bandwidths of the design are LTE700 (698~800 MHz), LTE2300 (2300~2400 MHz), and LTE2500 (2500~2690 MHz). Through the use of a C-shape broadside coupled feed structure, full operation in the lower band is achieved. The antenna itself uses two unequal path lengths to produce a low frequency band with two resonant modes. The required bandwidth is then adjusted using a couple feed, and finally placed over a ground plane via another C-type coupling element in order to enhance the two low-frequency matches. In the definition of the −6 dB reflection coefficient, the bandwidth of two basic modes in the low frequency band is 0.689~0.8 GHz. We adopt the definition of the −10 dB reflection coefficient for the high frequency mode, and its working frequency bands are shown to be 2.3~2.72 GHz. The antenna size is only 40 × 12 × 0.8 mm3 with a ground plane of 98 × 40 mm2.

Miniaturized DTV broadband slot antenna for handheld devices

In this paper, a novel broadband miniaturized antenna is presented. The proposed antenna can provide a wide operating bandwidth for DTV signal reception in the UHF band in mobile handheld devices. This antenna was utilizing eight quarter-wavelength slots with a compact size of 65×8.5 mm2. In proposed antenna, the L-shape 50-ohm microstrip line coupling fed was used to achieve broadband impedance matching. The antenna is able to realize an onmidirectional radiation characteristic across the entire operating band.

Near-field coupled antenna pair with transmission efficiency enhancement for WPT

In this paper, a near-field coupled transmitting-receiving antenna pair is proposed to achieve the maximum transmission efficiency. The antenna structure developed can achieve up to 77 % transmission efficiency in near-field coupling region. Additionally, through the rectifier circuit design, the front-end antenna pair will convert the radio frequency energy received into DC output. The maximum conversion efficiency of the proposed receiving rectenna is about 80% at the incident power level of 24 dBm and the load impedance of 1 kΩ. The output DC voltage of the rectenna is 13.12 V as the maximum conversion efficiency occurred.

Novel concepts in the design of near-field antenna for short-distance wireless power transmission with high transfer efficiency

This paper summarizes two novel concepts of antenna design for the applications of wireless power transmission at short distance. The design considers the near-field radiation characteristics of antenna to enhance the energy transfer efficiency. In particular, the first one considers the energy reaction when the transmitting (TX) and receiving (RX) antennas are very close to each other, where the mutual coupling may affect the S parameters of TX and RX antennas. On the other hand, the second one assumes the RX antenna is located in the radiation region of TX antenna, where the energy experiences energy divergence along propagation. The energy is thus focused by using an array of antennas phased to produce a focus region.

Stepped guard trace with the fewest shorting-vias to eliminate the ringing noise of coupled microstrip lines

This work presents a simple application for a guard trace that can be used to eliminate ringing noise. In the past, other researchers have proposed solutions using a guard trace with shorting-vias to reduce crosstalk. Since numerous shorting-vias degrade the signal integrity (SI) and reduce the flexibility of the circuit routing, we propose a stepped guard trace to minimize resonances between shorting-vias on the guard trace and to eliminate noise. The experimental results indicate that the proposed method, involving a stepped guard trace, elicits better performance than other methods.