Two-section Transmission Line Research Articles

Design and miniaturization of dual-band Wilkinson power dividers

Abstract In this paper, four differently shaped Wilkinson power dividers are presented by selecting the same physical length of two-section transmission lines, dual arbitrary frequency band Wilkinson power dividers can be achieved. The 2.4 GHz (WLAN) and 5.9 GHz (DSRC IEEE 802.11p) frequency bands are selected to complement the future development of multi-band, multi-standard transceivers. To improve physical separation and electrical isolation between the two output ports a parallel RLC circuit is employed. For verification, the simulated and measured performance results of dual-band Wilkinson power dividers implemented on the Rogers 4003C laminate are presented. The measurement results for the fabricated Wilkinson power dividers were in good agreement with theoretical simulation results and show dual-band characteristics.

Multiple design approach of dual‐band Wilkinson power divider with arbitrary transmission line ratio

A dual-band (DB) Wilkinson power divider with multiple design approach is proposed in this article, which consists of two-section transmission lines (TLs) with arbitrary length ratio, one parallel LC circuit, and one resistor. Compared with the former works with equal physical lengths, the total physical size of the two-section TLs can be decreased effectively. For a given DB frequency ratio, the maximum size reduction can be newly summarized as (n-1)/(2n), where n indicates the length ratio of two-section TLs. From the close-formed design equations, multiple solutions of circuit parameters are newly summarized for DB operation, thus circuit design could be much more flexible and more efficient. Furthermore, in order to compact the proposed circuit size, compensation technology for two coupled-line sections is also considered in circuit fabrication. Finally, design charts and an experimental circuit show good agreement with the theoretical simulation. Compared with the former work under the same design conditions: f2/f1 = 3.2, f1 = 1 GHz and f2 = 3.2 GHz, the proposed work provides compact circuit size and the size reduction is 25% with n = 2, m = 1.

Pulsed magnetic field device for laser plasma experiments at Shenguang-II laser facility.

A pulsed intense magnetic field device was developed for the Shanghai Shenguang-II (SG-II) laser facility. The device using a double-turn coil with 12 mm diameter is capable of producing a peak current of 42 kA with 280 ns rising edge and 200 ns flat top width. A peak magnetic field of 8.8 T is achieved at the center of the coil. A two-section transmission line composed by a flexible section and a rigid section is designed to meet the target chamber environment of SG-II laser facility. The flexible section realizes the soft-connection between the capacitor bank and the target chamber, which facilitates the installation of the magnetic field device and the adjustment of the coil. The rigid section is as small as possible so that it can be inserted into the target chamber from any smallest flange, realizing elastic magnetic field configuration. The magnetic coil inside the chamber can be adjusted finely through a mechanical component on the rigid transmission line outside the target chamber. The adjustment range is up to 5 cm in both radial and axial directions with ∼50 µm precision. The device has been successfully operated on SG-II laser facility.

Theory and Experiment of Two-Section Two-Resistor Wilkinson Power Divider With Two Arbitrary Frequency Bands

In this paper, a novel design theory of two-section two-resistor Wilkinson power divider (WPD) is introduced. By selecting two different physical lengths of two-section transmission lines (TLs), two arbitrary frequency band WPD can be achieved. Compared with the former work, the designable frequency ratio range $u$ can be extremely extended from $1 to $1 , general design equations for characteristic impedances, physical lengths, absorption resistors, and frequency ratio ranges are newly derived and proved from even- and odd-mode analysis. Because of no capacitors or inductors, the proposed WPD can be used for high-frequency applications. Spurious band of $S_{21}$ appears between two passbands under the condition of two different physical lengths; therefore, a $\Pi$ -type dual-band transformer is newly introduced to replace single TL for spurious band suppression. We proved that $\Pi$ -type structure could effectively suppress spurious band of $S_{11}$ , maintain two arbitrary frequency passband of $S_{21}$ , and provide an extra isolation band of $S_{32}$ at center frequency. Finally, three proposed WPD examples with $\Pi$ -type structure are selected with different frequency ratios, where frequency ratio $u = 4$ in Example A, $u = 6$ in Example B, and $u = 20$ in Example C are designed and fabricated in the experiment. Measured results show good agreement with the theoretical results.

A Dual-Band Port-Extended Branch-Line Coupler and Mitigation of the Band-Ratio and Power Division Limitations

In this paper, enhanced designs of port-extended branch-line coupler (BLC) are presented. Initially, the analysis of the conventional dual-band port-extended equal-division BLC is presented to deduce its operation from Riblet’s viewpoint. Subsequently, it is shown that extending the Riblet’s concept to dual-band design results in a novel dual-band BLC with arbitrary power division ratios. It has also been identified that the proposed design possesses a free design variable that allows realization of BLC with higher band-ratio. Furthermore, another BLC structure, capable of achieving enhanced band-ratio, utilizing two-section transmission line at each port is also proposed. All the reported design equations are in closed form and are very simple and do not go beyond a second-degree polynomial. The effectiveness of the proposed technique is demonstrated through test cases for equal and unequal power division ratio and for numerous band-ratio ( $= f_{2}/f_{1})$ . The good agreement between the electromagnetic simulated results and the measured results from the two unequal power division BLC prototypes, on Rogers RO4003C substrate, operating at 1.2 GHz/2.52 GHz and 1 GHz/2 GHz validate the proposed approach.

Dual‐frequency impedance matching networks based on two‐section transmission line

In this study, a practical and useful dual-frequency property of two-section transmission line (TSTL) terminated into a real impedance is reported. Moreover, to demonstrate some of its potential applications for the performance enhancement in dual-frequency impedance transformation problems, modified L- and T-type dual-frequency matching networks are presented. Specifically, the property is used to modify the conventional L-type matching network to improve its transformation-ratio and frequency-ratio performance. Furthermore, improvement in conventional dual-frequency T-type matching network is also demonstrated through the incorporation of the TSTL. All the results are analytical and in closed form with simple design equations. For validation, prototypes of the proposed L- and T-type matching networks operating concurrently at 1 GHz/1.45 GHz and 1 GHz/2 GHz, respectively, are designed and fabricated on FR-4 substrate. The obtained simulated and measured results clearly exhibit the usefulness of the proposed design schemes.

A flexible two-section transmission-line transformer design approach for complex source and real load impedances

A flexible two-section transmission-line transformer design approach for complex source and real load impedances

Generalized, miniaturized, dual-band Wilkinson power divider with a parallel RLC circuit

In this paper, a generalized, dual-band Wilkinson power divider consisting of a parallel RLC circuit and two two-section transmission lines is presented, and its circuit parameters, bandwidth ratios for lower and upper bands and miniaturization are discussed. A coupled-line section of loose coupling is introduced to take place a straight transmission line for miniaturization under the assumptions of linear phase characteristics and equal phase velocities of the even- and odd-modes. The relationship between normalized frequency and phase shift as electrical length increased are newly presented, and their S-parameters have also been simulated and discussed in details. Experimental result for miniaturized power divider showed good agreement with theoretical result, and the proposed dividers reported can be applied for practical use.

Low-pass filter with deep and wide stop band and controllable rejection bandwidth

Novel design of low-pass microwave filters based on cascading of identical unit cells is proposed. Dispersion relation is used to determine the cell parameters for a given relative stop-band width. For a filter consisting of two cells, each made of single- or two-section transmission lines, the design formulas and curves are presented. Based on them typical filters are designed, fabricated, and measured. The presented filters feature a deep stop band and a wide rejection band, which can be controlled within the proposed design procedure. The design procedure and the simulation results are verified experimentally by measurement of the fabricated structures containing two and three cells.

Compact Microstrip Wilkinson Power Dividers With Harmonic Suppression and Arbitrary Power Division Ratios

This paper describes a new Wilkinson power divider on a single-layer microstrip line that can reduce the occupied area, suppress the harmonic components, and/or provide the arbitrary power division ratios. It consists of two-section transmission lines, two inductors, and one isolation resistor. Four different designs have been conducted to investigate the capabilities of the structure. In addition, a compact divider along with harmonic suppression and a practical divider with a large power-dividing ratio has been constructed and measured. The simulation and measurement results are in good agreement with each other. This indicates that the structure can effectively be used as a power divider for miniaturized or arbitrary power division ratio applications.

Concurrent dual band class F power amplifier with novel harmonic control network

AbstractIn this article, we present a novel two‐section transmission line (TSTL) based dual band harmonic control (HC) technique applied to the design of high efficiency power amplifier (PA).The dual band TSTL design criterion is investigated for three particular cases and a class‐F HC network adopting all the three kinds of TSTLs is designed. For further demonstration, we realized and fabricated a harmonic tuned PA operating concurrently at 0.8 and 1.9 GHz. Experimental results have shown 75% and 72% PAE at 40.1 and 43.3 dBm output power in the two targeted bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:707–711, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26629

A Generalized 90° Impedance Transformer with Improved Spurious Suppression for Arbitrary Real Terminated Impedances

A generalized impedance transformer for arbitrary real terminated impedances is proposed in this article. This transformer mainly features 90° phase shifting at the operating frequency, matching for arbitrary real terminated impedances, and improved spurious suppression. It consists of two-section transmission lines and three parallel transmission-line stubs. By equating the ABCD matrixes of the proposed impedance transformer and conventional quarter-wavelength impedance transformer, closed-form design equations are obtained as a final analytical design approach. Several numerical and measured microstrip transformers with improved spurious suppression are presented. Finally, experimental performances verify this generalized structure and the proposed rigorous design equations.

DESIGN AND ANALYSIS OF DUAL-FREQUENCY MODIFIED 3-WAY BAGLEY POWER DIVIDERS

In this paper, difierent topologies of dual-frequency modifled 3-way Bagley polygon power dividers are designed and analyzed. Equal split power division is achieved at arbitrary design frequencies. In the flrst structure, two-section transmission line transformer is used to realize the dual-frequency operation. In the second and third structures, dual-frequency T-shaped and …-shaped matching networks are used. For the sake of simplicity, closed form design equations are presented for each matching network. To validate the design procedure, three examples are designed, simulated, and fabricated. The three matching networks are explored through these three examples. The design frequencies are chosen to be 0.5GHz and 1GHz.

Dual-Band Impedance Transformer Using Two-Section Shunt Stubs

This study presents a modified shunt-stub dual-band impedance transformer. The load impedances can be complex and unequal at two uncorrelated frequencies. The proposed transformer has two parts; each part is composed of a two-section transmission line. Similar to the single-stub matching network at a single frequency, a two-section transmission line is connected to the load and transforms the load impedances to normalized unit conductance at the two designated frequencies simultaneously. The resulting susceptances are then canceled out simultaneously by a two-section shunt stub at the two frequencies. The required nonlinear simultaneous equations are derived and solved to obtain the physical parameters of transmission lines. Rearranging the simultaneous equations to construct an objective function with only one unknown variable makes it easier to solve the equations. This approach avoids high-impedance transmission lines by choosing the characteristic impedance of each transmission line first. Return losses for various load impedances are simulated to validate the proposed structures. Good agreements between numerical and measured results validate the proposed structure.

A New Design Method for Unequal Dual-Band Modified Wilkinson Power Divider

A new design method for a dual-band (or dual-frequency) modified Wilkinson power divider with an unequal power dividing ratio is proposed in this article. First, a dual-band transformer with a flexible transmission line stub, which can be fabricated by a shorted-circuit stub or an open-circuit stub, for two arbitrary real impedances is analyzed, and the rigorous design method is obtained. It is necessary to apply the asymmetric structure in all unequal power dividers in order to obtain unequal power dividing; thus, an asymmetric structure, which consists of two equivalent asymmetric dual-band transformers with a parallel transmission line stub in the input matching part, is developed for an unequal dual-band power divider. A resistor is then used in this proposed power divider, as the effective isolation structure to obtain ideal isolation between two output ports while two-section transmission line transformers are applied to match impedances at two output ports. In the synthesis procedure, two groups of closed-form design equations of this unequal dual-band power divider without reactive lumped-elements are given. Furthermore, simulations of two sample examples have verified the new structure and the design method for this power divider in theory. Finally, a practical microstrip power divider, which operates at both 0.95 GHz and 2.28 GHz with 3 dB power dividing ratio, is designed, fabricated and tested. There are good agreements between the simulated and measured results.

Compact Dual-Band Equal Power Divider Circuit for Large Frequency-Ratio Applications

A novel design of compact dual-band equal power divider circuit for large frequency-ratio (greater than 3) applications is proposed in this paper. Topology of the circuit consists of two-section transmission-line transformers and a series RLC network for isolation. This power divider provides an equal power-dividing at two arbitrary frequencies which feature high center frequency-ratio. Besides, this power divider achieves good port matching and isolation. Theoretical derivations are presented and verified by measuring a 3-dB microstrip power divider operating at both 1 GHz and 4 GHz.

Dual-band microstrip-to-coplanar strip balun transition and loop antenna application

A microstrip-to-coplanar strip balun transition and its applicability to a single-fed dual-band tapered loop antenna are presented. The dual-band transition consists of a simple two-section transmission-line transformer and a two-section open-ended line. Closed-form design equations based on ideal transmission lines are derived and then verified with the examples of two designs. The application of the transition to a single-fed 0.9/1.8 GHz dual-band tapered loop antenna is then demonstrated. The measured performance of the antenna proves the validity of the proposed dual-band transition network.

Dual-Band Wilkinson Power Dividers Using a Series RLC Circuit

This paper describes a novel Wilkinson power divider operating at two arbitrary different frequencies. The proposed divider consists of two-section transmission lines and a series RLC circuit connected between two output ports. The circuit parameters for a dual-band operation are derived by the even/odd mode analysis. Equal power split, complete matching, and good isolation between two output ports are numerically demonstrated. Dual-band and broadband Wilkinson power dividers can be successfully designed. Finally, verification of this design method is also shown by electromagnetic simulations and experiments.

Design and realisation of dual-band 3 dB power divider based on two-section transmission-line topology

A new dual-band 3 dB three-port power divider with arbitrary impedance terminations is proposed. The structure is composed of a two-section transmission-line transformer and an isolation resistor. Each transmission line's electrical length is π/3 at the fundamental frequency. Based on an ideal transmission line model, new design equations and graphs are given. The technique is validated by the experimental results on a 3 dB 900/1800 MHz power divider with ZS=100 Ω and ZL=50 Ω. Good performances of the proposed power combiner/divider at both frequencies are obtained.

EM-based optimization exploiting partial space mapping and exact sensitivities

We present a family of robust techniques for exploiting sensitivities in electromagnetic (EM)-based circuit optimization through space mapping (SM) technology. We utilize derivative information for parameter extractions and mapping updates. We exploit a partial SM (PSM) concept, where a reduced set of parameters is sufficient for parameter extraction optimization. It reflects the idea of tuning and execution time is reduced. Upfront gradients of both EM (fine) model and coarse surrogates can initialize possible mapping approximations. We introduce several effective approaches for updating the mapping during the optimization iterations. Examples include the classical Rosenbrock function, modified to illustrate the approach, a two-section transmission-line 10:1 impedance transformer and a microstrip bandstop filter with open stubs.