An efficient method of designing dual‐ and wide‐band power dividers with arbitrary power division

Capability of microstrip nonuniform transmission lines (MNTLs) for construction of dual‐band and broadband unequal Wilkinson power dividers with arbitrary‐way, arbitrary frequency band operations, and arbitrary power divisions is evaluated. Also, the MNTL transformers are introduced for dual‐band/broadband matching of the unequal output impedances of the MNTL power divider with arbitrary output terminal impedances. The strip width of MNTLs is considered variable and is written as a truncated Fourier series expansion. To show the validity of the design procedure, three experimental MNTL Wilkinson power dividers, which are dual‐band two‐ and three‐way power dividers with different power divisions working at 1 and 3.4 GHz and one broadband equal power divider working from 0.4 to 1.8 GHz, have been designed and fabricated. In the first ones with power division of 1.5, outputs isolation and ports matching of less than ?30 dB are achieved. Next, an extended recombinant structure is presented for achieving three‐way MNTL power dividers with dual‐band operation. The measured isolation between outputs and ports matching are better than 30 dB and measured forward transmissions are between ?4.87 and ?5.45 in two passbands of the divider. Also, for the proposed broadband divider, the measured isolation between the outputs is better than 13 dB in 127% desired bandwidth. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

General design of impedance‐varying multi‐way Wilkinson power divider with bandwidth redefinition characteristics

In this article, a general design methodology of a multi‐way compact equal split Wilkinson power divider (WPD) with bandwidth redefinition characteristics and planar structure is proposed. Quarter‐wave matching uniform transmission lines in the conventional design are replaced with non‐uniform transmission lines (NTLs) governed by a truncated Fourier series. Even mode analysis is adopted to obtain NTLs with predefined bandwidth functionalities; whereas several isolation resistors are optimized in the odd mode analysis to achieve proper isolation and output ports matching over the frequency range of interest. Compactness is achieved by incorporating only one quarter‐wave wideband NTL transformer, with a length computed at the center frequency, in each arm. Two 3‐way WPDs with different frequency bands (i. e., 5‐9 GHz and 4‐10 GHz) and one 5‐9 GHz 4‐way divider examples are designed and simulated. Furthermore, a wideband 3‐way WPD operating over 4‐10 GHz band is fabricated and measured. Results show input and output ports matching and isolation below ?15 dB, and transmission parameters in the range of [–4.9,–6.2] dB and [–6,–7.5] dB across the operating band of the 3‐way and 4‐way WPDs, respectively.     

Dual‐band filtering power divider with unequal power division ratio and low‐loss characteristic

In this article, a dual‐band filtering power divider with unequal power‐division ability is proposed. Different from conventional equal power dividers constructed by filters or coupled resonators, noncoupled structures are employed in this design. As a result, low‐loss characteristic is realized for the proposed power divider. In this proposed structure, the dual‐band unequal power allocation is realized by replacing conventional single‐band λ/4 transformers with dual‐band ones (T‐junction structures). Three identical λ/4 stepped impedance resonators are properly attached to all the three ports of the proposed power divider to generate an extra transmission zero between two operational bands. Therefore, a filter‐like shaping in its S‐parameter results is obtained. A resistor is located between two outputs for output isolation. Mathematical derivations of the overall design procedure are also provided based on the circuit models and transmission line theory. Meanwhile, a resistor for output isolation is also included between two outputs, whose value can be calculated using given equations. For validation, a prototype operating at 0.9 and 2.1 GHz are designed, fabricated, and measured. The isolations between two outputs are 30 and 26 dB while the phase differences are only 2.5°and 4.9° at 0.9 and 2.1 GHz in the measurement, indicating good consistence of outputs. Measured |S21| and |S31| are ?(1.76 + 0.3) dB, ?(4.77 + 0.2) dB at 0.9 GHz and ?(1.76 + 0.6) dB, ?(4.77 + 0.5) dB at 2.1 GHz.     

Design of a wideband filtering power divider with good in‐band and out‐of‐band isolations

In this article, a wideband filtering power divider with good in‐band and out‐of‐band isolations is designed based on a hybrid Wilkinson and Gysel structure. To achieve a good in‐band response, two additional in‐band transmission poles can be introduced by installing the coupled‐line structures at each port. By mounting a stepped impedance open stub at the input port, two transmission zeros are generated near the passband to improve the passband skirt. Furthermore, the out‐of‐band rejection and isolation are achieved by the other two transmission zeros, which are produced by the open stub and the three coupled‐line sections mentioned above. Additionally, a good in‐band isolation is realized by the isolation resistor between output ports. For the demonstration, a wideband filtering power divider centered at 1.5 GHz with a 56% fractional bandwidth and 20‐dB isolation is designed and fabricated. The simulated and measured results are in good agreement with each other.     

A novel symmetrical Wilkinson power divider for dual‐band application

A symmetrical two‐way Wilkinson power divider with shifted output ports, much wide bandwidth and large frequency‐ratio is proposed for dual‐band application. The corresponding transcendental design equations are derived by using the even‐ and odd‐mode analysis. Moreover, the closed‐form scattering parameter expressions are derived. Transcendental design equations are solved and accurate numerical design parameters along with different frequency ratios are obtained. Finally, the proposed structure and design method are validated by simulated and experimental results of typical microstrip planar power dividers, the performance is clearly observed for the input and output matching, isolation and transmission characteristic very well at the two band frequencies. More specifically, the measured transmission characteristics of the divider are 3.11 dB/3.58 dB at the 1.0 GHz/3.5 GHz, respectively. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:102–108, 2014.     

A novel power divider with ultra‐wideband harmonics suppression based on double‐sided parallel spoof surface plasmon polaritons transmission line

A novel wideband power divider with ultra‐wideband suppression of harmonics is proposed in this paper. The power divider is composed of double‐sided parallel spoof surface plasmon polaritons transmission line (DSP‐SSPP‐TL) with periodical grooved bow‐tie cells. The cut‐off frequency of DSP‐SSPP‐TL can be flexibly adjusted by changing the parameters of bow‐tie cells. To demonstrate that, dispersion relations of the bow‐tie cells with different parameters are simulated, and three DSP‐SSPP‐TL counterparts are experimented. Then, a power divider centered at 3.31 GHz (f₀) is designed, fabricated, and measured. Experimental results indicate that the 10‐dB return loss bandwidth of the proposed power divider is about 146% from 0.9 to 5.73 GHz, and the upper stopband is extended up to 40 GHz (12.1 f₀) with the suppression level above 32 dB. Moreover, ultra‐wideband isolation between two output ports of the proposed power divider could be achieved by employing two lumped resistors between two DSP‐SSPP‐TLs.     

Four‐way waveguide power divider design for W‐band applications

In this article, a four‐way waveguide power divider is proposed for W‐band applications. The waveguide power divider employs an improved H‐plane T‐junction configuration. With the introduction of a metallic tetrahedral protrusion into the waveguide junction, good impedance matching can be achieved within a wide frequency range. First, a two‐way power divider is designed and analyzed, achieving almost identical amplitude and phase response at its two output ports. Then, other two same T‐junctions are cascaded, respectively, at the two output ports of the two‐way power divider to realize the proposed four‐way power divider. The four‐way power divider has been optimized, fabricated, and measured. The measurement results agree with the simulation ones reasonably, which demonstrates that the input return loss of the proposed four‐way power divider maintains above 14 dB across the entire W‐band with an insertion loss of less than 1.3 dB. Therefore, it could find wide applications in W‐band power splitting and combining modules.     

Ultracompact two‐way and four‐way SIW/HMSIW power dividers loaded by complementary split‐ring resonators

In this paper, two ultracompact power dividers based on the substrate integrated waveguide (SIW) and half‐mode SIW (HMSIW) technologies loaded by complementary split‐ring resonators (CSRRs) are presented. The presented structures are designed based on the theory of evanescent mode propagation. To obtain a size reduction, the CSRR unit cells are etched on the metallic surface of the SIW and HMSIW structures. First, a two‐way HMSIW power divider is reported. In this circuit, the concept of HMSIW is utilized aiming at a further size reduction in addition to the size reduction by the CSRR unit cells. Then, a four‐way SIW power divider is designed so that the direct coaxial feed is used for the input port and microstrip transmission lines are used for the output ports. Both two‐way and four‐way SIW/HMSIW power dividers at 5.8 GHz covering WLAN are designed, fabricated, and measured. They respectively have 0.18 × 0.21 λg² and 0.38 × 0.21 λg² total size. A fair agreement between simulated and measured results is achieved. The measured insertion losses are 0.5 ± 0.5 and 0.6 ± 0.5 dB for the two‐way and four‐way SIW/HMSIW power dividers, respectively, in the operating band of interest.     

Dual‐passband bandpass‐filtering power divider using half‐mode substrate integrated waveguide resonator with high frequency selectivity

In this paper, a half‐mode substrate integrated waveguide (HMSIW) power divider with bandpass response and good frequency selectivity is proposed. The proposed power divider includes input/output microstrip lines, four HMSIW resonators, cross‐coupling circuits, and an isolation resistor. The dual‐band bandpass‐filtering response is obtained by using the dual‐mode slotted HMSIW. To get good frequency selectivity, the input/output cross‐coupling circuits have been used, and several transmission zeros can be observed. A dual‐band filtering‐response HMSIW power divider is designed, fabricated and measured. The total size of the fabricated power divider is 0.58λg × 0.45λg. The measured results show a reasonable agreement with the simulated ones. The measured central operating frequencies of the dual‐band HMSIW power divider are at 2.43 and 3.50 GHz, respectively. The measured 3‐dB fractional bandwidth is about 13.3% and 6.3% in the two passbands, and the measured output isolation is about 20 dB.     

Double‐layer microstrip ultra‐wideband filtering power divider with high selectivity and large isolation

In this article, a compact double‐layer microstrip ultra‐wideband (UWB) filtering power divider with high selectivity and isolation is proposed. The filtering power divider consists of a multimode resonator at the top layer coupled with a pair of branch lines at the bottom through a slotline in the middle ground. The slotline provides strong coupling between the two layers and equally distributes the power to two branch lines. The resistor loaded about a quarter‐wavelength away from the slotline achieves high isolation within UWB range. The UWB filtering properties with controllable transmission poles and zeros as well as power splitting with enhanced isolation have been analyzed. The adjustable transmission zeros of the filter unit enables the bandwidth control of the filtering power divider. Finally, a UWB filtering power divider operating at 3.1 to 10.6 GHz has been designed, fabricated, and measured. It achieves a compact size of only 26 × 28 mm², high isolation about 20 dB, and good out‐of‐band suppression of 40 dB.     

Six‐port balanced network with high unequal power division ratio using shorted coupled lines

A novel 6‐port balanced network with high unequal power division ratio using shorted coupled lines is proposed in this letter. The design parameters of the proposed power divider are analyzed according to transmission line theory. Two double‐sided parallel‐strip line 180° phase inverters loaded with 4 isolation resistors are used to realize high isolation for the power dividing output ports. A planar balanced network with bandwidth of 40.5% (power division ratio: 1:10) for the differential mode and wideband 23% common mode suppression is designed and fabricated. The measured results show good agreement with the theoretical expectations.     

Wideband bandpass filtering branch‐line balun with high‐isolation

The wideband bandpass filtering branch‐line balun with high isolation is presented in this paper. The proposed balun can be designed for wideband performances by choosing a proper characteristics impedance of input vertical transmission line and odd‐mode impedance of parallel‐coupled lines. The proposed balun was designed at a center frequency (f₀) of 3.5 GHz for validation. The measured results are in good agreement with the simulations. The measured power divisions are ?3.31 dB and ?3.24 dB at f₀ and ?3 ± 0.17 dB within the bandwidth of 0.95 GHz (3 GHz to 3.95 GHz). The input return loss of 24.09 is measured at f₀ and higher than 20 dB over the same bandwidth. Moreover, the measured output losses are better than 11 dB within a wide bandwidth. The isolation between output ports is 20.32 dB at f₀ and higher than 13.2 dB for a broad bandwidth from 1 GHz to 10 GHz. The phase difference and magnitude imbalance between two output ports are 180° ± 4.5° and ± 0.95 dB, respectively, for the bandwidth of 0.95 GHz.     

Design of an ultra‐wideband power divider with harmonics suppression

The design of an ultrawideband (UWB) power divider with harmonics suppression is presented. With the proposed approach, the size of the quarter‐wavelength transmission line can be reduced and the high order harmonics can be suppressed. The design equations are deduced by transmission line theory. A prototype power divider operated at UWB band is designed and fabricated. Experimental results show good performance of the proposed design. In addition, a stop‐band with rejection level more than 20 dB is from 17.3 to 24.5 GHz. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:299–304, 2015.     

Equal and unequal quad‐band Gysel power dividers

This article presents for the first time a quad‐band Gysel power divider capable of achieving equal and unequal power division at four arbitrary frequencies. The structure of the proposed divider is similar to its single‐band counterpart but loaded with quad‐band reactive networks. The design procedure and theoretical analysis of the proposed divider are presented. A quad‐band Gysel power divider with equal division and another with 2:1 unequal division are designed at the operational frequencies of 0.85, 1.6, 2.4, and 3 GHz. Simulation and measurement results of the two dividers are presented, and good performance is observed at each band. For both designs, the realized power division ratios are within 1 dB from their ideal values, whereas the matching and isolation levels are below ?10 dB at the four bands.     

A 200 W broadband high power amplifier using hybrid power combining network and digital level control

In this article, a 2 to 6 GHz solid‐state power amplifier with 53 dBm output power has been analyzed, designed, and fabricated. To achieve a wideband high output power, we introduce a 16‐way hybrid power combiner based on microstrip planar binary and parallel structures. The simulation and measurement results of the proposed hybrid power combining network (PCN) show that the maximum power combining efficiency is around 86% with the insertion loss of around 0.6 to 1.5 dB and an isolation of 20 dB between the ports. Also, to compensate the output power variations due to the thermal and operating frequency changes across the bandwidth, a digital level control (DLC) unit utilizing an agile control algorithm is proposed which decreases the output power variations to 2% of the desired output power. A cooling heatsink fan system has been also designed in order to transfer the heat generated power to the air. The measured output power for the applied input continuous wave is higher than 52.5 dBm. In addition, the power added efficiency (PAE) is better than 15% across the wide portion of the bandwidth and the measured third‐order intermodulation is about 20 dBc (average).     

A novel quasi symmetrical design of the three‐way Gysel power divider using ideal phase inverters

A novel quasi symmetrical three‐way Gysel power divider with frequency‐independent isolation and impedance matching is proposed. Equal magnitudes of the reflection coefficients for the input and the output ports of the three‐way divider can be obtained despite the asymmetrical structure and the different terminal impedances. The divider is analyzed in terms of its equivalent four‐port network. Quasi symmetrical property (|S₁₁| = |S_ii|, i = 2‐4) is proved which means the input port (port. 1) will automatch when the output ports are matched. Closed‐form equations are derived for the design. For verification, based on the microstrip/slotline PI, two examples, which include a three‐way Gysel PD with port impedances (50, 50, 50, 50) Ω, and an ultra‐wideband three way Gysel PD with port impedances (50, 100, 100, 100) Ω with the center frequency of 4 GHZ are designed, fabricated, and measured respectively. The measured results are in great agreement with the simulated ones.     

Dual‐band filtering power divider with widely separated passbands

This article presents a dual‐band microstrip filtering power divider with widely separated passbands. The design topology is mainly constructed by two pairs of dual‐mode resonators, an open‐ended input line and two T‐shaped output lines. Owing to the field symmetry at the two sides of the input line, two identical signals are coupled to the resonators and finally transmitted at two output ports. Since each pair of the employed dual‐mode resonators can be independently designed, widely separated dual‐passbands response is specified and derived in this work with the even‐mode/odd‐mode analysis. Moreover, good isolation with wide isolated frequency band is realized by introducing resistors between each pair of resonators. To validate the design concept, a prototype centering at 2.39 and 3.83 GHz is implemented following the given design procedure. Measured results of the fabricated circuit agree well with the simulated ones, exhibit high frequency selectivity, good port‐to‐port isolation, and port matching.     

A new dual‐band single‐ended‐to‐balanced filtering power divider

This article proposes a new dual‐band single‐ended‐to‐balanced (SETB) filtering power divider (FPD), which shows the excellent characteristics of wideband common‐mode (CM) suppression and good selectivity. By employing the structure of double‐sided parallel‐strip line with a mid‐inserted conductor and a T‐shaped defected ground structure etched in the mid‐inserted conductor, out‐of‐phase behavior and high CM suppression can be achieved successfully. Besides, to realize dual‐wideband filtering performance and high selectivity, two pairs of step impedance stubs (SIS) loaded quarter‐wavelength central line‐terminal‐shorted three parallel‐coupled microstrip lines structure are adopted. Meanwhile, two pairs of resistors are introduced so as to realize excellent isolation. To verify effectiveness of the design method, a prototype of dual‐band SETB FPD which operates at 3.2 and 4.9 GHz is designed, fabricated, and tested. Final results exhibit that the new dual‐band SETB FPD possess high selective dual‐band differential mode response, wideband CM suppression, and excellent isolation between the balanced output ports.     

Composite corporate traveling‐wave power dividers for slot array waveguide antennas

A composite corporate traveling‐wave power divider is presented. The single‐layer structure is composed of three parts: two interdigital traveling‐wave subsections combined with a power splitter. An iterative design technique is described in which the divider is split into a number of basic blocks. Large‐scaled networks are then easily designed because the whole structure does not need to be simulated. A method to take into account the insertion losses is also proposed and bandwidth enhancement is discussed, which is done by increasing the number of corporate layers. Experimental results are also shown for a 1:4 subsection. It provides equal output power with 0.5 dB of insertion loss. The phase‐shift between output ports is close to the specifications of ?150° at 30 GHz, with an error of less than 2°. It is also shown that this topology is well suited for frequency scanning antenna. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

A broadband out‐of‐phase gysel power divider based on a dual‐band circuit with a single fixed isolation resistor

Based on the double‐sided parallel‐strip lines with an inserted conductor as a virtual ground, a high power divider with dual‐band/broadband response and frequency‐independent 180° phase difference between the output ports is implemented in this paper. The circuit topology employs a single commercially available external isolation resistor as well as moderate line impedances (15–100 ohm), making it suitable for high‐power applications. Precise closed‐form design equations on the basis of even‐ and odd‐mode analysis are derived. In addition to the wide range of frequency band ratios from 1 to 2.65, broadband response is also obtained by selecting the proper value of frequency band ratios. To substantiate the design equations and theory, a circuit with 2:1 frequency ratio and 84.5% bandwidth referring to 16 dB isolation and 12 dB return loss values is developed. To the authors' knowledge, this is the widest bandwidth reported for out‐of‐phase high power dividers. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2016.