Lingxiao Jiao

The art of power dividing: A review for state-of-the-art planar power dividers

In this paper, massive state-of-the-art planar power dividers are presented and discussed. The innovations of these superiorly-performanced power dividers lie in the performance breakthrough, physical configurations and function integrations. Eventually, based on the trend presented, the future of the power dividers is predicted. This paper might have inspiration significance to illuminate the way for the development of power dividers.

Graphene-based Yagi-Uda antenna with reconfigurable radiation patterns

This paper presents a radiation pattern reconfigurable Yagi-Uda antenna based on graphene operating at terahertz frequencies. The antenna can be reconfigured to change the main beam pattern into two or four different radiation directions. The proposed antenna consists of a driven dipole radiation conductor, parasitic strips and embedded graphene. The hybrid graphene-metal implementation enables the antenna to have dynamic surface conductivity, which can be tuned by changing the chemical potentials. Therefore, the main beam direction, the resonance frequency, and the front-to-back ratio of the proposed antenna can be controlled by tuning the chemical potentials of the graphene embedded in different positions. The proposed two-beam reconfigurable Yagi-Uda antenna can achieve excellent unidirectional symmetrical radiation pattern with the front-to-back ratio of 11.9 dB and the10-dB impedance bandwidth of 15%. The different radiation directivity of the two-beam reconfigurable antenna can be achieved by controlling the chemical potentials of the graphene embedded in the parasitic stubs. The achievable peak gain of the proposed two-beam reconfigurable antenna is about 7.8 dB. Furthermore, we propose a four-beam reconfigurable Yagi-Uda antenna, which has stable reflection-coefficient performance although four main beams in reconfigurable cases point to four totally different directions. The corresponding peak gain, front-to-back ratio, and 10-dB impedance bandwidth of the four-beam reconfigurable antenna are about 6.4 dB, 12 dB, and 10%, respectively. Therefore, this novel design method of reconfigurable antennas is extremely promising for beam-scanning in terahertz and mid-infrared plasmonic devices and systems.

Comments on “Novel Dual-Band Matching Network for Effective Design of Concurrent Dual-Band Power Amplifiers”

A novel dual-band matching network for concurrent dual-band power amplifiers has been proposed and discussed by Fu in January 2014. The first stage matching network effectively accomplished real-to-complex impedance transformation by utilizing a transmission line, a short-circuited stub and an open-circuited stub. However, the obtainment of the values of the electrical parameters are realized by tuning and observing Smith Chart, no analytical design methodology given. In this comment, rigorous design equations of the real-to-complex matching network are extracted, and two numerical instances are demonstrated for verification. Additionally, an error about the input impedance in original paper is corrected.

Dual-Band Dual-Mode Substrate Integrated Waveguide Filters with Independently Reconfigurable TE101 Resonant Mode.

A novel perturbation approach using additional metalized via-holes for implementation of the dual-band or wide-band dual-mode substrate integrated waveguide (SIW) filters is proposed in this paper. The independent perturbation on the first resonant mode TE101 can be constructed by applying the proposed perturbation approach, whereas the second resonant mode TE102 is not affected. Thus, new kinds of dual-band or wide-band dual-mode SIW filters with a fixed or an independently reconfigurable low-frequency band have been directly achieved. In order to experimentally verify the proposed design method, four two-cavity dual-band SIW filters, which have different numbers of perturbation via-holes in each cavity, and a two-cavity dual-band SIW filter, which includes four via-holes and eight reconfigurable states in each cavity, are designed and experimentally assessed. The measured results indicate that the available frequency-ratio range from 1 to 1.3 can be realized by using four two-cavity dual-band SIW filters. The center frequency of the first band can be tuned from 4.61 GHz to 5.24 GHz, whereas the center frequency of the second one is fixed at around 6.18 GHz for the two-cavity dual-band SIW filter with four reconfigurable states via-holes. All the simulated and measured results show an acceptable agreement with the predicted data.

Dual-band coupled-line bandpass filter with independently tunable bandwidths

This paper reports a novel dual-band coupled-line bandpass filter. Comprising a quadruple-mode coupled-line resonator, this proposed filter could filter signals on two frequency bands. After introducing two varactors, one of the four resonances could be continuously altered by changing the capacitance of the varactors, thus the two frequency bandwidths could be independently tunned. In this paper, the detailed explanation for its operation is given, and the agreement between the expected and practical performance sufficiently confirms the robustness and effectiveness of this proposed filter.

A Novel Balanced-to-Unbalanced Complex Impedance-Transforming In-Phase Power Divider

In this paper, a simple and compact planar balanced-to-unbalanced in-phase power divider with arbitrary terminated impedances is proposed based on the coupled-line structure and a single grounded resistor. By using the even-/odd-mode analysis and the traditional transmission-line theory, the complete design procedure and analytical equations are obtained to achieve good performances for differential-mode transmission, common-mode suppression, phase difference, arbitrary terminated impedances, and isolation. For demonstration, two different prototypes with 50-to-

A novel three-dimensional dual-band balun with frequency-independent phase difference and complete ground

50~\Omega

Novel Dual-Band Coupled-Line Quadrature Couplers with Unequal Power Division

matching and complex impedance transformation are designed, fabricated, and measured. Good agreement can be observed between simulated and measured results.

An Impedance-Transforming Coupled-Line Wilkinson Power Divider with Port Isolations and Extensions

A novel three-dimensional (3D) dual-band balun employing the double-sided parallel-strip line (DSPSL) with inherent impedance-transforming capability and complete ground is presented in this paper. The proposed balun is mainly composed of two mutually perpendicular printed circuit boards (PCBs), one of which is a horizontal feeding plane with a slender slot and the other of which is a mounted board vertical to the former. An unbalanced input port and two balanced output ports are totally located at the feeding plane. Utilising the configuration of DSPSL, two different dual-band impedance transformers of two sections are placed in the top and bottom layers of the vertical mounted board respectively. Thus, the transformers are applicable to transform impedances at two frequencies simultaneously. Furthermore, the 180° phase difference is frequency-independent, which facilitates the broadband operation. For verification, two numerical examples with different frequency ratios are designed and simulated, one of which is fabricated on a Rogers 4350B board. Both the simulated and measured results exhibit excellent performance and agree well with each other. In essence, this 3D balun is comprised of a single-layer planar circuit configuration. Consequently, owing to easy integration and low cost, it will be widely applied in the balanced radio frequency components.

Homodyne Digitally Assisted and Spurious-Free Mixerless Direct Carrier Modulator With High Carrier Leakage Suppression

ABSTRACT A dual-band coupled-line 90° unequal coupler is proposed in this paper. It is simply composed of three pairs of coupled lines and four port extensions. Analytical design methodology and detailed design guidance are given, which significantly simplifies the design procedure. Due to the utilization of coupled lines, the proposed coupler possesses tight circuit configuration, and since the degree of freedom is increased for the even- and odd-mode characteristic impedances, the coupled lines enable the dual-band operation. Meanwhile, the coupler can operate with unequal power division. Furthermore, the employment of port extensions eliminates the additional insertion loss caused by additional port lines. Eventually, two prototypes of the proposed coupler are designed and fabricated. The good agreement between the expected and measured results confirms the design methodology in this work to be correct and effective.