A Generalized Dual-Frequency Transformer for Two Arbitrary Complex Frequency-Dependent Impedances

The purpose of this letter is to propose a dual-frequency transformer for two arbitrary complex frequency- dependent impedances (ACF-DIs) and present a generalized T-junction power divider (T-JPD) operating at dual-band with arbitrary power-dividing ratios based on the proposed transformer. By the rigorous analysis of transmission line theory, the closed-form design equations for this generalized transformer are obtained. Using the analytical design method, a kind of generalized T-JPD can be designed to operate at two different frequencies with different power-dividing ratios. Furthermore, numerical examples are simulated and a microstrip T-JPD operating at 1 and 2.4 GHz with different power-dividing ratios (1.5 and 2 dB, respectively) is fabricated. Good agreements between the simulated and measured results can be observed.      

双波段射频功率放大器理论与设计

提出了一种新型的双频阻抗变换器结构,该阻抗变换器采用T 型与装型结构相结合的方式,经理论推导和仿真优化,设计的双频阻抗变换器可实现任意两个频率上的任意两个不同复数阻抗到实数阻抗的变换。采用双频偏置电路,实现了在两个工作频率下的扼流,最终设计了一款可同时应用于TD-LTE 和GSM 网络的双波段射频功率放大器。相比于其它的多模多频带功率放大器,该双频阻抗变换器理论推导过程简单,容易实现,并可实现68%以上的功率附加效率,同时具有高输出增益和高平坦度的特点,整体电路结构简单。     

A Multi-Band Transformer for Two Arbitrary Complex Frequency-Dependent Impedances

A multi-frequencies transformer for two arbitrary complex frequency-dependent impedances is presented. Design equations of the proposed transformer are derived, and particle swarm algorithm can be used to solve the resulting nonlinear equations. Some numerical examples for two-, three-, and four-section transmission line transformer were presented to verify the validity of the proposed design.     

Synthesis of lumped dual-frequency impedance transformers for complex loads using inverters

Novel lumped dual-frequency impedance transformers (DFITs) for arbitrary frequency dependent complex loads (FDCLs) are synthesized using the concepts of capacitive and inductive inverters. Such a dual-frequency impedance transformer is constructed with one Pi-shaped lumped inverter and two shunt susceptance blocks at two sides, and get simplified after susceptance merging. The shunt susceptance blocks have specified susceptance values at two frequencies and are realized with lumped circuits of certain topologies. Design formulas of the DFITs are derived and are validated by two examples. Compared with a former technique, this method uses less lumped elements and provides one design freedom, so largest matching bandwidths can be achieved by comparing a series of possible designs.     

Stepped transformers on TEM-transmission lines

The paper presents comparative analysis of the properties of impedance stepped transformers both with monotonous and nonmonotonous step-to-step impedance variation. A miniature stepped transformer of a new structure based on a cascade of an even number of uniform transmission line sections has been synthesized. Section lengths are considerably shorter than a quarter of the central wavelength, and the section impedances alternate. The proposed transformers are the simplest to implement among the available analogs. As an example, the results of the solution of the Chebyshev approximation problem for the four- and six-section transformers of different specifications are given     

Design of impedance transformers by the method of least squares

The method of least squares is applied to the theory of small reflections of transmission lines to develop numerical algorithms for the design of stepline and tapered line impedance transformers to match two impedances over a frequency band. The transformer characteristic impedance function is expanded by polynomials, pulse functions, approximate operators, and piecewise linear functions to construct an error function for the input reflection coefficient which, after minimization, gives the line impedance and length. The computer programs could be used to design a transformer under the specified conditions and then to optimize the design under the constraints of a problem     

宽带Wilkinson 功分器综合公式的缺陷与改进

首先介绍了3 种宽带Wilkinson 功分器的综合方法,重点阐述了最为常用的Cohn 的设计方法,并指出 随着功分器节数的不断增加,在利用Cohn 的设计公式计算隔离电阻阻值时会产生负数的问题。为此,通过引入一 个调整参数改进Cohn 的设计公式,实现了节数更多情况下隔离电阻阻值的准确计算。在计算功分器各级传输线特 性阻抗的过程中,提出了一种基于MATLAB 程序的多项式化简方法,实现了任意带宽的切比雪夫阻抗变换器参数的 快速计算。此外,还给出了一个8 级到15 级的功分器设计参数表格,作为对Cohn 给出的设计表格的扩展。最后,利 用改进后的设计公式,设计了一个1 ~15GHz 的宽带Wilkinson 功分器。仿真和测试结果证明了这种方法的有效性。     

A finline PSK modulator for W-band

A 90° phase switch in finline technique has been developed for application in a W-band homodyne network analyzer. It is realized on a 0.127 mm fibre reinforced teflon substrate in a standard WR 10-waveguide. It employs two low capacitance beam-lead PIN diodes mounted in series to the finline. The waveguides are connected via Dolph-Chebyshev tapers. The analysis of this circuit shows that the diode junction capacitance imposes certain constraints for the wave impedances which must be realized. They can only be met with overlapping antipodal finlines. There are several analytical solutions with different lengths and wave impedances of the transmission line sections. The choice has been taken with respect to bandwidth in the limits imposed by the range of wave impedances which can be realized. Between 90 and 105 GHz, the phase error of the realized modulator is below ±2.5°, and the amplitude imbalance is less than 0.5 dB.     

Impedance and Polarization-Ratio Transformations by a Graphical Method Using the Isometric Circles

The isometric circles for the direct and inverse linear fractional transformations can be used for transformations of impedances and polarization ratios. In the Ioxodromic case an inversion is performed in the isometric circle of the direct transformation, followed by a reflection in the symmetry line of the two circles, and a rotation around the origin of the isometric circle of the inverse transformation. In the nonloxodromic case only the first two operations have to be applied. Three illustrative examples are given: the first shows the transformation of the right half of the complex impedance plane into the unit circle (Smith Chart); the second gives a circular proof of the Weissfloch transformer theorem; the third shows an example of cascading, Iossless, two terminal-pair networks.     

一种新型低功率双频微波整流电路

提出一种应用于低功率的双频输入微波整流电路,采用双频匹配网络和直通滤波器分别实现二极管的输入匹配和抑制双频的基频与高次谐波,当输入为1 mW 时,实测结果显示,该整流电路在850 MHz 和1.9 GHz 频率处分别获得了47%和81.4%的整流效率,输出电压分别为0.53 V 和0.70 V,在输入双频信号时输出电压为0.85V,转换效率为60.8%,其低功率输入性能在国内具有先进性,并对RFID、嵌入式传感器电子设备无线输能等领域的应用具有实际参考价值。     

Dual-frequency disc antenna studied by cavity method

A double-stub adjusting procedure is used to obtain quasi-identical input impedances and radiation patterns at both resonances of a dual-frequency microstrip antenna. In addition, the cavity method is adapted so as to be applied for the evaluation of radiation pattern as well as the input impedance of the above-mentioned antenna.     

Transmission Line Impedance Matching Using the Smith Chart (Letters)

A graphical computation method is described for transforming complex load impedances into resistive load impedances using transmission line matching sections. The Smith chart is used even though the characteristic impedance normalizing factor is unknown.     

Simple design of dual-frequency unequal power-divider

It is economical to have one base station antenna array for the dual-frequency operation of the mobile phones. From transmission line theory, it is shown that a power-divider can be made simply from a two-section transmission line transformer in each branch     

Equivalent Circuit for Partially Dielectric-Filled Rectangular-Waveguide Junctions

The problem of electromagnetic-wave propagation in junctions between two symmetrically, partially dielectric-filled waveguides was investigated, and the solution is presented in the form of a two-port equivalent circuit, This equivalent circuit includes an ideal 1:1 transformer, which is connected to transmission lines with impedances equal to those of the two waveguides, in cascade with a T network. Elements of the T network and the characteristic wave impedances of these partially dielectric-filled waveguides have been studied, and the results are presented in graphs for different dielectric constants, slab thicknesses, and operating frequencies.     

基于TD-LTE 和GSM 双频功率放大器设计与实现

通过对传输线理论和阻抗变换原理的深入研究,分析推导了三枝节微带传输线级联结构和具有开路 枝节的三节微带传输线结构两种双频匹配网络。基于该公式推导,设计并实现了同时工作在TD-LTE 网络和GSM 网络的双频功率放大器。仿真与实测结果表明在设计的两个工作频段内,增益为16dB 左右且增益平坦度小于依 1dB,饱和输出功率点的功率附加效率接近70%,输出功率及小信号测试均满足设计要求,验证理论正确性的同时, 也为双频功率放大器的研究与推广提供了设计参考。     

A new hybrid filter to dampen resonances and compensate harmoniccurrents in industrial power systems with power factor correctionequipment

A new hybrid power filter is presented for three phase industrial power systems which include passive power factor correction equipment (PFC). The hybrid filter damps resonances occurring between line impedances and the PFC. In addition, the hybrid filter topology can be used to compensate harmonic currents. The capacitors of the PFC, which generally cause resonant problems in harmonic distorted networks, can be used for passive filtering by connecting a transformer with a low magnetizing inductance in series hence creating a single harmonic trap. The primary side of the transformer is connected to a low VA-rated three-phase current controlled inverter which builds the active part of the hybrid topology. Simulation results and experimental results are presented verifying the damping and harmonic compensation performance of the proposed topology     

Broadband extended cantilever model for magnetic component windings

The extended cantilever model is modified to enable broadband representation of multiple magnetic windings using s-domain transfer functions. A linear formulation for extracting the parameters is proposed in which the current-sense impedances do not have to be assumed negligible. The model has been implemented in a circuit simulator that supports transfer function blocks. It has been verified experimentally using a five-winding power transformer. The experimental transformer is simulated embedded in a two-transistor forward converter to examine simulation speed and convergence issues     

Interpretation of multifrequency complex resistivity data for alayered Earth model

A method is proposed for interpreting data obtained by measuring mutual impedances of dipole-dipole configurations on the surface of a layered Earth. Such data are assumed to be available over a sufficiently broad band of temporal frequencies and dipoles interspacing. For a given grounded transmitting dipole, two receiving grounded dipoles of selected different orientations are used. The electromagnetic circuit coupling is effectively cancelled at any given frequency by appropriate Bessel transform operation on the measured complex impedances versus spacing. The next step is to infer the complex resistivities of the Earth's layers at each frequency. From such inferred data at a sufficient number of spot frequencies, the dispersive behavior of the resistivity of each layer is deduced. This proposed procedure is demonstrated by applying it to computer-simulated data on a two-layer Earth with encouraging results     

Characterization of On-Chip Transformer Using Microwave Technique

The figure-of-merit of an on-chip transformer is investigated by using a power gain approach in this paper. Adopting a microwave viewpoint, contrary to the lumped-circuit concept, to characterize the on-chip transformer, the transfer power gain between primary and secondary terminals is plotted in the Smith chart by changing the load impedances. Therefore, the peak value of power gain is found at a specific load impedance. To discuss the power loss of two transformers with different metal widths, the device layouts are carefully designed to maintain identical self- and mutual inductances in the transformers' coils. Results show that impedance matching plays a key role in improving the power gain of an on-chip transformer.     

Direct-Coupled Cavity Filters for Wide and Narrow Bandwidths

Direct-coupled resonator filters in transmission line are discussed. The resonators consist of sections of transmission line coupled either by series capacitances or shunt inductances. Over narrow frequency bands, such filters show characteristics similar to those of lumped-constant filters and their design is straightforward. The design of direct-coupled resonator filters over wide (as well as narrow) frequency bands is presented here using the quarter-wave transformer as a prototype circuit. Several numerical examples (with fractional bandwidths between 10 per cent and 85 per cent) are worked out to illustrate the method. It is shown that the response can be improved by optimizing the line impedances.