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The following topics are dealt with: low distortion power amplifier technology; wide band planar filters; microwave applications; CAD and numerical techniques; low profile and small antennas; microwave filters; high power GaN HEMT; tunable and metamaterial filters and resonators; terahertz and microwave applications; mobile antennas; microwave medical and biological applications; planar antennas;...
This paper presents an experimental investigation on the wideband intermodulation distortion compensation characteristics of a 3.5-GHz feed-forward power amplifier for mobile base stations. The fabricated 3.5-GHz band 140-W class feed-forward power amplifier employing gallium nitride high electron mobility transistors (GaN HEMTs) achieves the intermodulation distortion compensation bandwidth of 160...
This paper presents a rigorous way to quantify the role played by higher baseband impedances in determining baseband electrical memory effects observed in power transistors under two-carrier excitation. These effects typically appear not only as asymmetrical distortion terms in the frequency domain, but also more reliably as a recognizeable hysteresis or looping in the dynamic transfer characteristics...
The Envelope Elimination and Restoration (EER) technique has attracted significant attention recently because of its high efficiency under back-off operation. Memoryless Digital Predistortor (DPD) is indispensable for an EER power amplifier (PA) because of the EER PA's strong nonlinearity due to the dynamic power supply voltage. However, performance of the memoryless DPD is significantly degraded...
This paper is concerned with offline digital predistortion (DPD) for linearization of radio frequency (RF) high power amplifiers (PAs). We propose an adaptive scheme for selecting basis functions for both direct and indirect learning digital predistortion architectures. The adaptive scheme has the advantage of reducing the complexity and, at the same time, increasing the convergence rate and stability...
For wideband communication systems, memory effects in power amplifiers (PAs) always become significant, which commonly make intermodulation-distortions (IMDs) response asymmetric in a two-tone test. The Volterra series is a general method to analyze and model the nonlinear PAs with the memory effects, while the complexity in the large number parameters to be calculated is a major limitation. In this...
In this paper, a micostrip parallel-coupled dual-mode ring resonator is analyzed based on its equivalent transmission line circuit and the even- and odd-mode method. Closed-form formulas relating the transmission zeros and 3dB fractional bandwidth of the resonator to the circuit parameters are derived, and are verified effective by using a circuit simulator and an electromagnetic simulator. A bandpass...
In this study, a wideband diplexer is proposed and the associated design concepts are also briefly discussed. First, two broadside-coupled bandpass filters are employed in the design phase so as to broaden the passband bandwidths of proposed diplexer. Next by adopting the stepped-impedance resonators in the design of the bandpass filter (BPF A) for the low-band channel, one may shift its spurious...
The design procedure of a wideband band-pass filter (BPF) which consists of an inter-digital finger resonator and parallel coupled lines is proposed in this paper. The design of the bandwidth was described by using the even and odd mode characteristic impedances in the resonator structure. The parallel coupled line was also analyzed in the same manner. The parameters of those elements in combination...
A novel ultra wideband (UWB) bandpass filter (BPF) with dual notch bands using the coupled stepped impedance resonator (SIR) is presented. The filter consists of a square-etched multi-mode resonator (MMR) and two coupled SIRs to provide dual notch bands at 5.2 and 5.8 GHz over the standard UWB frequency range. The |S21|-magnitude and the frequency positions of the notch bands can be determined by...
In this paper, a compact ultra-wideband (UWB) bandpass filter (BPF) with a controllable notched band is proposed and implemented for the application in UWB wireless communication system. Stepped-impedance stub loaded resonator (SISLR), which can generate three resonant modes over the UWB passband with two transmission zeros at both lower and upper stopband, is developed in the filter design with aperture-backed...
A major obstacle of wireless energy harvesting is to convert relatively low power wireless RF energy into sufficiently high DC voltage for practical use. This paper explores and studies a topology where several voltage doublers are connected in series to boost up the DC output voltage from the wireless energy harvesting circuits. A prototype has been designed and fabricated to test the feasibility...
Battery exchange cost or the battery itself of sensor terminals is a serious problem to construct a wireless sensor network. The objective of the present study is to develop a ZigBee sensor network powered by external microwave in order to realize a battery-less or wirelessly-charged wireless sensor network. Our designed microwave power receiving system consists of a power receiving antenna, a rectification...
Metamaterials are a new ordered composites that exhibit exceptional electromagnetic properties. In particular, artificial dielectric materials and transmission lines with both negative permittivity and permeability have attracted widespread interest in recent years. In this paper, to focus microwave energy, metamaterial and left hand transmission lines are applied. The specific phenomenon of metamaterial...
It is an essential problem to unbind lignin, which is one of the components of woody biomass, efficiently when we produce bioethanol from woody biomass. We study on a pretreatment system by microwave irradiation to solve this problem. It is important to understand the permittivity characteristics of liquid compounds, which consist of woody biomass, water, solvents and acid, to design an efficient...
In order to lower the car's weight, fuel consumption, this paper proposes an intra-car communications system in which the wire harness is replaced with the radio hoses. The proposed intra-car communications system uses a radio hose, a metalized flexible rubber hose that works as an oversized waveguide. The proposed system will provide much higher reliability than conventional wireless communications...
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