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.     

A broadband coplanar waveguide to rectangular waveguide power divider using a slot

In this article, a broadband coplanar waveguide (CPW) to rectangular waveguide power divider using the dipole slot is proposed. The power divider consists of an input CPW port and two output rectangular waveguide ports. The CPW to rectangular waveguide power divider using the dipole slot has a return loss larger than 15 dB and an insertion loss equal to 3.08–3.27 dB in the whole X‐band (8.2–12.4 GHz). Furthermore, to broaden the bandwidth, the dipole slot is replaced by the bow‐tie slot. The CPW to rectangular waveguide power divider using the bow‐tie slot yields a return loss larger than 16 dB and an insertion loss equal to 3.05–3.29 dB from 8 to 13 GHz, which exceeds the X‐band. To verify our design, power dividers that use the dipole slot or the bow‐tie slot are fabricated and measured. The measurement results of both power dividers are in good agreement with the simulation results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

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.     

A W‐band broadband power divider/combiner using two parallel antisymmetric tapered probes

In this article, a broadband microstrip‐to‐waveguide transition with antisymmetric tapered probe as well as a W‐band power divider/combiner using dual proposed antisymmetric tapered probes is presented. Because of tapered microstrip shapes and metallic steps, the proposed transition is proved to be broadband, efficient, and compact. The insertion loss of the transition sample is less than 0.56 dB between 75 GHz and 100 GHz. Under the assistance of the gradually changed waveguide and dual parallel tapered probes, the operating band of the power divider/combiner has been significantly improved, which is adequate to work in the whole W‐band. A back‐to‐back prototype of the divider/combiner is fabricated and measured. The measured insertion loss of the single divider/combiner is less than 0.29 dB between 90 GHz and 100 GHz, and agrees well with the simulations. Because the circuit size is smaller than 8.0 mm × 2.2 mm (Thanks to the excellent performance and compact size), the proposed design can find wide applications in miniaturized MCM/MMIC systems.     

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.     

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.     

Generalized high‐isolation n‐way Gysel power divider with arbitrary power ratio and different real terminated impedances

An exact closed‐form design approach for a generalized high‐power n‐way Gysel power divider is proposed. The power divider could be designed to achieve an arbitrary power ratio with the flexible multiway application, arbitrary real terminated impedance, excellent isolation, and easy fabrication through both planar and three‐dimensional structures. Moreover, this improved power divider could maintain high power processing capacity through the coaxial cavity transmission line and grounding resistances. The exact analytical solutions related to ideal port matching and high isolation are obtained based on the circuit and transmission‐line theory. To verify the proposed approach, a compact 3‐way coaxial power divider with a pre‐designed power ratio of 1:1.5:2 and four different real terminated impedances of 50, 55, 60, and 65 Ω is designed and fabricated. Excellent agreement is achieved between the simulated and measured results. Measurements from 4.7 to 5.7 GHz show that the return losses of all input and output ports are better than 15 dB. The maximum insertion loss is 0.5 dB, and the phase imbalance is approximately less than 6.1°. In addition, the isolation between any two output ports is better than 23 dB from 4.5 to 6 GHz. Meanwhile, the power handling capability can reach the maximum power of the commercial 50 Ω SMA connectors (2.098 kW).     

A Ka‐band power divider/combiner using two side‐inserted magnetic coupling semicircular ring probes

A Ka‐band power divider/combiner with dual magnetic coupling semicircular ring probes is proposed in this paper. Firstly, a broadband microstrip‐to‐waveguide transition with semicircular ring probe is designed based on the side‐inserted structure of magnetic field excitation in a rectangular waveguide. The insertion loss of the proposed transition is less than 0.7 dB in Ka‐band assisted by the dual symmetrical broadband probes and rectangular waveguide. Then, the divider/combiner is proposed using the new transition with magnetic coupling from narrow wall into the rectangular waveguide. The bandwidth of the divider/combiner is more than 9 GHz (from 27 to 36.7 GHz), and the insertion loss of the single divider/combiner is less than 3.3 dB. Finally, the performance of the proposed divider/combiner is validated through simulations and measurements. The proposed design has potential applications in microstrip circuits.     

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.     

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.     

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.     

Filtering balanced‐to‐single‐ended power dividing network

In this article, the filtering balanced‐to‐single‐ended power dividing networks are proposed. Except the fundamental functions of differential‐mode transmission, common‐mode suppression, and out‐of‐phase single‐ended output ports with isolation, the proposed designs show the advantages of wide controllable range of differential‐mode bandwidth, multiple transmission zeros (TZs), and wide bandwidth for high out‐of‐band suppression. The frequencies of TZs, bandwidth, isolation, and common‐mode suppression can be controlled by the parameters. For demonstration, three prototypes (Deigns I, II, and III) with two, four, or six TZs are implemented. The measured results show that design I (II and III) has an insertion loss of 0.38 dB (0.7 dB and 0.8 dB), an operating bandwidth of 12.5% (7.5% and 6.9%), and a bandwidth for 30‐dB out‐of‐band suppression of 0.06f₀ (0.09f₀ and 0.14f₀). The isolation and common‐mode suppression inside the passbands of the three prototypes are all larger than 17 and 38 dB, respectively.     

Compact planar substrate‐integrated waveguide diplexers with wide‐stopband characteristics

Compact planar substrate‐integrated waveguide (SIW) diplexers with wide‐stopband characteristics are presented for the first time based on collaborative multispurious mode suppression techniques including the harmonic staggered technique, centered coupling windows, and offset‐centered output ports. The coupling scheme using common dual‐mode resonator coupled with multiple single‐mode resonators is adopted here to eliminate the T‐junctions for size and loss reduction, and the dual‐mode coupling controlling technique we previously proposed is also employed to allocate the fractional bandwidths (FBWs) of the two channels flexibly based on the FBW design graph. Additionally, by combining the harmonic staggered technique, centered coupling windows, and offset‐centered output ports, good out‐of‐band rejections can be achieved and excellent wide‐stopband characteristics have been implemented intrinsically. Two prototypes including second‐order and third‐order SIW diplexers are synthesized, designed, fabricated, and tested as demonstrations, extending the stopbands to 1.78f₁ and 2.04f₁ with the rejection levels better than 17.5 and 20 dB, respectively.     

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 covering Ka‐band two‐way switch filter module using a three‐line and an E‐plane waveguide band‐pass filters

A millimeter‐wave ultrawideband two‐way switch filter module is presented in this article. The switch filter module covers whole Ka‐band (26–40 GHz), and is composed of two wideband band‐pass filters and two monolithic microwave integrated circuit (MMIC) single pole two throw (SP2T) switches. One filter is realized using E‐plane iris waveguide band‐pass filter, and another is realized by a novel 11‐pole three‐line microstrip structure band‐pass filter. Compared with the traditional three‐line filter, the proposed three‐line filter not only retains virtues of the traditional three‐line filter, but also resolves drawbacks of it, which include discontinuities between adjacent sections, many parameters of design, and no effective matching circuits at input/output ports. The developed switch filter module is fabricated using hybrid integrated technology, which has a size of 51 × 26 × 9.8 mm³, and interconnections between MMICs and microstrip are established by bond wires. The fabricated switch filter module exhibits excellent performances: for two different states, the measured insertion loss and return loss are all better than 7 and 10 dB in each pass‐band, respectively. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:305–310, 2015.     

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.     

Wideband filtering power dividers using single‐ and double‐layer periodic spoof surface plasmon polaritons

In this article, four wideband power dividers (two are filtering power dividers) using single‐ and double‐layer periodic spoof surface plasmon polaritons (SSPPs) are proposed. Double‐sided parallel‐strip line is used to realize the wideband and low loss for the double‐layer SSPPs. T‐shaped SSPPs power dividers with large bandwidth, wideband isolation, and low loss using double‐layer SSPPs to single‐layer SSPPs transition are realized. Conventional coplanar waveguide is used as the output ports for the single‐layer SSPPs. Moreover, two new SSPPs power dividers with filtering performance are realized with adding via holes in the double‐layer SSPPs. The theoretical analysis, parametric study, and design procedure for these wideband power dividers are illustrated. In addition, for validity demonstration, four wideband SSPPs power dividers are fabricated in microstrip technology and characterized. Good agreements can be observed between the measured and simulated results, indicating good potential applications in the integrated plasmonic devices.     

Modified circular common element four‐port multiple‐input‐multiple‐output antenna using diagonal parasitic element

A four‐port multiple input multiple‐output (MIMO) antenna with common radiating element is proposed for 2.4 GHz Wi‐Fi applications. It comprises a modified circular radiator fed by four identical modified feedlines, partial ground planes, and a diagonal parasitic element (DPE). The parasitic element is used to enhance the interport isolation. The antenna has a 2:1 Voltage standing wave ratio (VSWR) impedance band 2.34‐2.56 GHz and nearly omnidirectional radiation patterns. The radiation efficiency is more than 79% and gain is 2 dBi at resonant 2.43 GHz. The isolation in the given frequency band is 10 dB. At the 2.43 GHz, the isolation between adjacent ports (1, 2 and 1, 4) is 14 dB and between opposite ports (1, 3) is 12 dB. The mean effective gain (MEG) ≤ ?2.7 dB and envelope correlation coefficient is <0.01. The ?10 dB total active reflection coefficient bandwidth is 202 MHz. The antenna is designed for a Wi‐Fi device and the effectiveness of antenna has been checked for distance of ½ feet from the human head. The specific absorption rate (SAR) is found to be ≤0.17 W/Kg by CST simulation tool.     

Single section,octave bandwidth,high‐power combiner in the UHF band

In this work, a planar broadband high‐power combiner in the ultra‐high‐frequency band (UHF) is presented. The proposed broadband combiner is a modified version of the conventional Wilkinson power combiner. The isolation resistor of 100 Ω in the conventional Wilkinson combiner is replaced by two 50 Ω terminating resistors. Two overlay couplers transform the terminating resistors to a floating resistor between the input branches. Terminating resistors are preferred to a floating resistor because of higher power handling and lower parasitics. Even‐ and odd‐mode method is employed for the analysis. The design goal is 20 dB isolation and ports return loss in an octave bandwidth. To verify the design concept, a high‐power combiner in the frequency range of 470 to 860 MHz used for digital video broadcasting‐terrestrial (DVB‐T) applications is designed and constructed. Full‐wave simulations are compared with measurements. The fabricated power combiner handles 400 W output power. Analytical formulations presented in this work are not restricted to UHF band and can be used to design an octave bandwidth combiner in other frequency bands.     

A high‐isolation dual‐polarized quad‐patch antenna fed by stacked substrate integrated waveguides for millimeter‐wave application

A high‐isolation dual‐polarized quad‐patch antenna fed by stacked substrate integrated waveguide (SIW) that is suitable for millimeter‐wave band is proposed in this paper. The antenna consists of a quad‐patch radiator, a two‐layer SIW feeding structure and two feeding ports for horizontal and vertical polarization. The two‐layer stacked SIW feeding structure achieves the high isolation between the two feeding ports (|S₂₁| ≤ ?45 dB). Based on the proposed element, a 1 × 4 antenna array with a simple series‐fed network is also designed and investigated. A prototype working at the frequency band from 38 to 40 GHz is fabricated and tested. The results indicate that the proposed antenna has good radiation performance at 38 GHz that covers future 5G applications.