Jean-Fu Kiang

Dual-Band Circularly Polarized Cavity-Backed Annular Slot Antenna for GPS Receiver

A circularly polarized (CP) cavity-backed annular slot antenna for GPS receiver is designed to operate in both the L1 and L2 bands of the Global Positioning System (GPS). The measured impedance bandwidths with VSWR less than 2 are 3.7% (1.19-1.235 GHz) and 1.2% (1.565-1.585 GHz), respectively, the measured 3 dB axial-ratio (AR) bandwidth are 0.9% (1.220-1.231 GHz) and 0.6% (1.572-1.581 GHz), respectively. A cavity is designed to render a unidirectional radiation pattern.

Resonance in cylindrical-rectangular and wraparound microstrip structures

A rigorous analysis of the resonance frequency problem of both the cylindrical-rectangular and the wraparound microstrip structure is presented. The problem is formulated in terms of a set of vector integral equations. Using Galerkins method to solve the integral equations, the complex resonance frequencies are studied with sinusoidal basis functions which incorporate the edge singularity. The complex resonance frequencies are computed using a perturbation approach. Modes suitable for resonator or antenna applications are investigated. The edge singularity of the patch current is shown to have no significant effect on the accuracy of the results. It is shown that the HE/sub 10/ modes of the cylindrical-rectangular and wraparound patches are more appropriate for resonator applications. The HE/sub 01/ and TE/sub 01/ modes of the cylindrical-rectangular and wraparound patches, respectively, are efficient radiating modes. >

Dualband Split Dielectric Resonator Antenna

A dualband dielectric resonator antenna (DRA) is designed by splitting a rectilinear dielectric resonator (DR) and carving notches off the DR. It is observed that notches engraved at different positions affect different modes. Removal of dielectric material from where the electric field is strong incurs a significant increase in resonant frequency. The abrupt change of normal electric field across the discontinuities reduces the -factor and increases the impedance bandwidth. Both the and modes incur broadside radiation patterns on the -plane. The proposed DRA can cover both the worldwide interoperability for microwave access (WiMAX, 3.4-3.7-GHz) and the wireless local area network (WLAN, 5.15-5.35-GHz) bands.

Compact Multi-Band H-Shaped Slot Antenna

A compact triple-band H-shaped slot antenna fed by microstrip coupling is proposed. Four resonant modes are excited, including a monopole mode, a slot mode, and their higher-order modes, to cover GPS (1.575 GHz) and Wi-Fi (2.4-2.485 GHz and 5.15-5.85 GHz), respectively. Sensitivity study of the slot geometry upon the resonant modes have been conducted. The measured gains at these four resonant frequencies are 0.2 dBi, 3.5 dBi, 2.37 dBi, and 3.7 dBi, respectively, and the total efficiencies are -2.5 dB, -1.07 dB, -3.06 dB, and -2.7 dB, respectively. The size of this slot antenna is only 0.24λ0×0.034λ0, where λ0 is the free-space wavelength at 1.575 GHz, hence is suitable to install on notebook PCs and handheld devices.

A 5-GHz CMOS Frequency Synthesizer With an Injection-Locked Frequency Divider and Differential Switched Capacitors

A phase-locked loop (PLL)-based frequency synthesizer at 5 GHz is designed and fabricated in 0.18-mum CMOS technology. The power consumption of the synthesizer is significantly reduced by using an injection-locked frequency divider (ILFD) as the first frequency divider in the PLL feedback loop. The synthesizer chip consumes 18 mW of power, of which only 3.93 mW is consumed by the voltage-controlled oscillator (VCO) and the ILFD at 1.8-V supply voltage. The VCO has the phase noise of - 104 dBc/Hz at 1-MHz offset and an output tuning range of 740 MHz. The chip size is 1.1 mm times 0.95 mm.

Design of Wideband LNAs Using Parallel-to-Series Resonant Matching Network Between Common-Gate and Common-Source Stages

A method is proposed to design wideband low-noise amplifiers (LNAs) made of cascaded common-gate (CG) and common-source (CS) stages with a parallel-to-series resonant interstage matching network. The first CG stage has a dual-band response, and the second CS stage has higher gain between these two bands. By applying the proposed interstage matching technique, conjugate matching is achieved at high and low bands, while the midband loss is compensated by the second stage. The output network of the first stage and the input network of the second stage resonate at the same frequency. Two wideband LNAs are designed based on this method and implemented in 0.18- μm RF-mixed signal CMOS process. The first LNA operates at 3.1-10.3 GHz, having 9.6-12.71 dB of power gain and 2.5-3.9 dB of noise figure (NF) at the power consumption of 13.4 mW. The second LNA operates at 14.3-29.3 GHz, having 8.25 ± 1.65 dB of power gain and 4.3-5.8 dB of NF at the power consumption of 13.9 mW.

Integral equation solution to the guidance and leakage properties of coupled dielectric strip waveguides

The guidance and leakage properties of single and coupled dielectric strip waveguides are analyzed using the dyadic Greens function and integral equation formulation. Galerkins method is used to solve the integral equation for the dispersion relation. The effects of the geometrical and the electrical parameters on the dispersion relation are investigated. A method for predicting the occurrence of leakage is proposed. The properties of the even and the odd leaky modes are also investigated. Results are compared with previous analysis and are shown to be in good agreement. >

Analysis of linear coaxial antennas

Two types of linear coaxial antennas, coaxial-colinear antennas, and slotted coaxial antennas are studied to check the possibility of using them as the base-station antenna in personal communication systems. The slot voltages and input impedance of linear coaxial antennas are obtained by using a transmission-line analysis where the radiation effect is accounted by a shunt and a serial admittance, respectively. The current distribution is obtained by solving an integral equation using the method of moments. The radiation pattern and directivity are then obtained from the current distribution and the reflection coefficient inside the coaxial cable. Factors analyzed include frequency, coaxial filling permittivity and segment number.

Estimation on Location, Velocity, and Acceleration With High Precision for Collision Avoidance

An approach is proposed to estimate the location, velocity, and acceleration of a target vehicle to avoid a possible collision. Radial distance, velocity, and acceleration are extracted from the hybrid linear frequency modulation (LFM)/frequency-shift keying (FSK) echoed signals and then processed using the Kalman filter and the trilateration process. This approach proves to converge fast with good accuracy. Two other approaches, i.e., an extended Kalman filter (EKF) and a two-stage Kalman filter (TSKF), are used as benchmarks for comparison. Several scenarios of vehicle movement are also presented to demonstrate the effectiveness of this approach.

A 30 GHz Active Quasi-Circulator With Current-Reuse Technique in

An active quasi-circulator at 30 GHz is designed and fabricated in TSMC RF mixed signal CMOS technology. The current-reuse technique is integrated with a common-source stage to form the quasi-circulator core while reducing the power consumption at the same time. The transmitter-to-receiver leakage is alleviated by the out-of-phase cancellation of signals from two paths. The isolation and insertion loss between other pairs of ports are improved with buffer stages. All the measured isolations are higher than 12 dB, all the insertion losses are lower than 7.9 dB, and the total power consumption is 15 mW.