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This paper proposes a power divider with integrated filtering characteristics. To enhance selectivity at the two output ports, T-shaped grounded transmission lines are incorporated into the series-connected parallel-coupled lines of the bandpass filter. Additionally, by adopting a hairpin-type configuration within the filter, extra transmission zeros are introduced, resulting in sharper roll-offs and higher attenuation around the passband edges. The proposed filtering power divider is fabricated on a Rogers RO4003C substrate, with a center frequency of 3.5 GHz and an overall circuit size of $0.4~\lambda _{\mathrm {g}} \times 0.29~\lambda _{\mathrm {g}}$ . The performance of the circuit is validated through a comparison of simulated and measured results.

This paper presents a planar slot structure antenna array with a simple structure of a substrate-integrated waveguide for D-band communication bands. This antenna achieves wideband and high gain characteristics. The antenna is fed by a power divider in the corporate structure and a transition structure is designed from the WR-6.5 metal waveguide to the SIW. To improve bandwidth, a cavity is added to the transition structure to provide multiple propagation modes. The proposed antenna is designed incrementally, from a $2\times 6$ antenna array to a $4\times 6$ antenna structure. After verifying with simulations and measurements, the designed $4\times 6$ antenna array has a frequency coverage of 130-131, 135-136, and 138.7-142 GHz and an average radiation gain of about 15 dBi. The proposed antennas are considered ideal for the D-band communication system. Therefore, the proposed antenna is compact, easy to integrate in RF circuits, and high gain, which makes it suitable for development and application in D-band communications.

This paper introduces a novel design methodology for a dual-band branch-line coupler (DBBLC) that, for the first time, facilitates practically unlimited band ratio, enhanced flexibility in power division, and arbitrary port termination impedance concurrently. This approach ensures precise power distribution, matching, and isolation requirements by utilizing a generalized coupler core paired with an L-section impedance-matching network. This paper details an innovative and comprehensive analytical strategy for DBBLC design, which overcomes the limitations noted in prior research by deriving a generalized formula for the power division ratio (k) and simplifying the design equations to decrease complexity. This method enables the simultaneous realization of varied power division ratios, frequency ratios (r), and port impedances ( $Z_{p}$ ), thus offering remarkable design versatility. The effectiveness of this new analytical design methodology is corroborated through several design examples. Moreover, two prototype models operating at 1 GHz/2.5 GHz ( $r=2.5, k=0$ dB) and 1 GHz/2 GHz ( $r=2, k=4.77$ dB) frequencies, constructed on Rogers’ RO4003C substrate, exhibit >22 dB return loss, 25 dB isolation at all the targeted frequencies. Therefore, the development and validation of this new DBBLC structure, as demonstrated by the strong correlation between our simulated and experimental findings, not only surpasses the capabilities of existing models, but also broadens the applicability of dual-band couplers in modern wireless communication systems.

There has been growing interest in the field of wireless power transfer (WPT), especially for a high-power (Watt-level) application. Rectifiers are essential components for WPT, as they convert incoming RF into DC power. However, conventional Schottky diodes used in WPT exhibit their highest efficiency at low power levels typically less than few Watts. To address this limitation, we introduce a power dividing rectenna system that can handle beyond several Watts of input RF power. The proposed rectenna consists of a single patch antenna integrated with a radial power divider, whose output ports are connected to rectifiers. In this way, incident RF power can be distributed into lower levels at which Schottky diode-based-rectifier can accommodate. Via simulation and measurement, we demonstrate that the input power (about 10 W) received through the proposed structure can be uniformly distributed to each output port of the divider to be rectified at lower power levels, which are then combined at DC to provide several Watts of DC power. The proposed rectenna can be utilized in WPT applications requiring beyond several Watts. Furthermore, by configuring the proposed structure into an array, even higher power handling can be achieved for applications that require hundreds of Watts.

This article reports a wide-band power divider with ultra-wide harmonic suppression. The filtering power divider consists of a Wilkinson power divider and a filter merged into a single structure. For filtering purposes, a novel suppressor cell is designed using resonators of various shapes. The power divider exhibits an operational frequency of 1.64 GHz, encompassing a fractional bandwidth (FBW) of 57 percent, ranging from 1.151 GHz to 2.08 GHz. Notably, it effectively suppresses a total of 24 harmonics, attaining a rejection level exceeding −15 dB. The measured in-band isolation, input return loss, insertion loss, and output return loss are determined at 1.64 GHz to be −23 dB, −36 dB, −3.03 dB, and −18 dB, respectively. These results showcase the superior performance of the proposed design compared to existing state-of-the-art solutions.

In this paper, a slotted waveguide array antenna (SWAA) is designed for S-band high-power microwave (HPM) applications. The single element of the array consists of ten Gaussian distributed slots on the broad wall of the waveguide, integrated with inside grooves. The 4-element SWAA configuration is designed to achieve a relatively high gain (24.6 dB) along with highly isolated (−24 dB) radiating elements. The gain enhancement and mutual coupling (MC) reduction is achieved by optimizing inside-grooved regions. An efficient $1\times 4$ power divider (PD) of identical phase and magnitude (−6 dB) at its output ports, is designed to feed the array elements. The radiation performance of SWAA is further improved by developing a dielectric radome. The proposed design is compact having dimensions $8.46\lambda _{0}\times 4.3\lambda _{0}\times 1.47\lambda _{0}$ , and offers return loss (RL) better than −25 dB with side lobe level (SLL) of −15 dB and −20 dB in E and H-plane, respectively. The designed array has 95.78% antenna efficiency over 3.8% measured bandwidth with 63% aperture efficiency. It has been demonstrated that the developed system, because of effective suppression of unwanted surface current, provides ±22° beam scanning without causing a significant reduction in its gain. The technique, without adding any complexity in the system, offered a 7% improvement in the gain when compared with a similar design.

Substrate-integrated-waveguide (SIW) technology can eliminate the limitations associated with conventional rectangular waveguides, i.e., bulky structures and production complexity at higher frequencies. Moreover, SIW technology replaces microstrip structures eliminating the drawback of excessive radiation leakage at higher frequencies. SIW power dividers are key elements in SIW antenna array synthesis. A SIW power divider’s design procedures are more complicated than conventional microstrip power dividers. However, no comprehensive review with design guidelines of substrate-integrated-waveguide (SIW) power dividers has been reported. In this paper, different types of SIW power dividers based on their configurations, functionality, and operating principles are analyzed and some recommendations are made for selection purposes. A comprehensive design guideline for SIW power dividers is given in this paper through a comparative study of T- and Y-type SIW junctions. These guidelines are based on key parameters, including insertion loss, isolation, co-phase bandwidth, return loss bandwidth, and phase balancing. This study provides valuable information for selecting and designing the best possible configuration of SIW power dividers for specific applications in microwave and millimeter-wave frequency ranges. A case study of a Ku-band SIW power divider is performed for a Ku-band soil moisture radiometer SIW antenna array.

This paper presents a new approach to introducing scattering parameters for dispelling doubts and misconceptions. Normalization of voltage and current is first introduced for the subsequent descriptions of normalized matrices. The analogy with lossless transmission lines is used to define voltage waves in terms of circuit voltages and currents. Scattering parameters are interpreted as reflection and transmission coefficients for real normalizing impedance. Power considerations are made to interpret scattering parameters as power ratios. The condition for the lossless circuit is derived, and it is shown that the definitions of the voltage waves satisfy maximum power transfer conditions for real input impedance. Reciprocity conditions are derived to show that the normalized, not the unnormalized scattering matrix, is symmetric. The application of losslessness and reciprocity in filter design is clarified. Next, it is shown why definitions of forward and reverse voltage have to be changed for complex normalizing impedances. The relationships of matrices for complex normalizing impedance are shown to reduce to those for real normalizing impedance. The procedure for changing normalizing impedance is given, and its application for amplifier design is briefly described. The difference between circuit symmetry and physical symmetry is pointed out. Finally, it is shown how odd and even mode analysis arises from a mathematical consideration of symmetrical two-port networks. A straightforward discussion of Wilkinson power divider is given to illustrate the application of these modes.

A TM-mode-pass polarization rotator and power divider with an arbitrary beam-splitting ratio constructed by an adiabatic taper, a spatial mode order convertor and a multi-mode interferometer (MMI) is proposed on the silicon-on insulator (SOI) platform. Both arbitrary power splitting and polarization selection-rotation can be realized in this single device. The measurements show that a continuously adjustable beam-splitting ratio from 1:99 to 99:1 within a 33.2 mW power consumption from 1520–1580 nm has been realized for the proposed device.

A micromachined ridge gap waveguide power divider operating at 220–325 GHz is presented. The device is fabricated by SUEX dry film photoresist. Dry film photoresist can be used to obtain geometrical features with high accuracy using a robust fabrication process. The designed power divider has simple geometrical features and a wide band performance. The measured transmission coefficients are equal to −3.5 ± 0.4 dB at 220–325 GHz and the measured input reflection coefficient is below −12 dB at 220–325 GHz. The measurement results are in good agreement with simulations, demonstrating that the proposed fabrication method is suitable for the fabrication of waveguide components operating at the millimeter and sub-millimeter wave range. The presented low-loss ridge gap waveguide power divider may enable cost-effective and rapid fabrication of passive devices such as high gain antennas operating up to THz frequencies.

An axially symmetric radial waveguide power divider, which utilizes a specific Cycloidal-Like tapered transition between a central coaxial launcher and a radial waveguide, is presented in this paper. In order to broad the operation band, the change of impedance of the coaxial to radial waveguide transition is investigated, and an analytic expression for the shape of the transition is obtained. A simple electromagnetic modeling for the stepped radial matching network is developed, and its characteristics are analyzed in detail using the circuit method. Eventually, a stepped-by-stepped design procedure for the power divider is established for the design of the radial waveguide power divider. A twenty-way radial waveguide divider is designed, fabricated, and measured to validate the proposed method. The measurements show that the return loss at the input port is better than 20 dB over almost the full ${Q}$ -band (33 to 48 GHz), while the amplitude/phase imbalance are within ±0.5 dB and ±3°, respectively. The simulated and measured results demonstrate a high degree of agreement.

A common-mode (CM) suppression-based passive microwave measurement system for microfluidic applications is proposed in this article. The proposed system contains three parts, including differential microwave microstrip sensor, phase shifter, and power divider. The differential structure of the proposed microstrip sensor is composed of two split-ring resonator (SRR)-based microstrip sensors and four 3-D metallic walls. Interdigital capacitances (IDCs) are inserted between two SRRs to enhance the density of electric field. Moreover, two 3-D metallic walls are erected on both sides of each IDC, which can increase the concentration of electric field further. Power divider, phase shifter, and differential structure constitute the measurement system. Assuming that a signal with frequency of ${f}_{{0}}$ is input into input port, and going through by power divider, the CM signals will be generated. Then, passing by phase shift, differential structure, and combiner to output port, theoretically, when the phase difference between two branches is 180° at ${f}_{{0}}$ , the corresponding magnitude of output signal will be zero at ${f}_{{0}}$. Therefore, the transmission coefficient will be infinitesimal at ${f}_{{0}}$ (CM signals are suppressed), and an ultrahigh ${Q}$ will be obtained. An equivalent circuit model is presented to reveal the operating principle of the sensor. The variations of relative frequency shift and normalized ${Q}$ are adopted to extract the complex permittivity of liquid sample. In the experiment, the sensitivity of detecting real permittivity is about 0.05%, and a high ${Q}$ of about 1432 is realized. All in all, the proposed microwave sensor has a huge superiority over some previously reported ones. [ABSTRACT FROM AUTHOR]

This study presented an implementation of weighted-polarization multiple-input–multiple-output (MIMO) antenna for wireless body area networks at 2.45 GHz. The weight function determined by considering the variation in the cross-polarization power ratio (XPR) and the antenna tilt angle was realized by a two-way power divider (PD), where tunable power ratio range of proposed PD could not only cross the boundary of equal power ratio (k2 = 1), but also maintain a wide tunable range at the same time. The patch array antenna fed by the proposed PD consists of microstrip lines, capacitors, resistors, and varactor diodes can overcome the polarization mismatch in dynamic off-body channel due to the variation in radio-propagation environment and human movement by adjusting the bias voltages. The experiment of 2 × 2 MIMO channel capacity was conducted using a three-dimensional spatial fading emulator. The measured and simulated results are in good agreement. Under the considered condition of arm-swinging angle and the XPR, the tunable power ratio range of proposed PD can be realized from −1.25 dB to 20 dB; therefore, it is suitable for radio-frequency control antenna to obtaining high data transmission in future wearable MIMO applications. [ABSTRACT FROM AUTHOR]

In this article, a class of $2^{n}$ -way wideband filtering power dividers (FPDs) is presented and designed with a wide isolation band. It consists of ($2^{n}-1$) two-way power-dividing units and $n$ three-line coupled lines. The basic two-way power divider is achieved by replacing a simple isolation resistor of the conventional Wilkinson power divider with a modified isolation network, so as to improve the bandwidth of better-than-20-dB isolation band from 40% to 120%. The modified isolation network is composed of one quarter-wavelength coupled line, two quarter-wavelength transmission lines, and one resistor. The three-line coupled line is introduced at each output of the proposed FPD to improve its frequency selectivity and passband bandwidth. Furthermore, after placing one additional isolation resistor on each three-line coupled line, the number of output ports in the proposed power divider could be doubled without introducing more two-way power-dividing units. Finally, a prototype two-way and two prototype four-way wideband FPDs with different occupied sizes are designed and fabricated. The feasibility of the proposed design method is verified by the good agreement between the simulated and measured results. [ABSTRACT FROM AUTHOR]

In this article, a high-isolation power divider with ultrawideband characteristics for simultaneous operation in two adjacent bands is proposed. The power divider is developed based on a four-port coplanar Magic-T. The difference port of the Magic-T consists of a double-ridge gap waveguide (RGW) that supports quasi-TEM mode transmission, which provides the benefit of its broadband characteristics and allows for facilitated assembly. In addition, an inline microstrip line (MSL) containing a probe is inserted into the opposite side of the difference port to form the sum port. This basic configuration has actually achieved high isolation between the output arms and low return loss at each port, and however, its isolation bandwidth is limited by the narrowband matching of the sum port. To overcome this difficulty, a three-port microstrip T-junction is connected in series to the sum port of the Magic-T, resulting in a five-port 3-dB power divider with a wide isolation bandwidth. The process of considering this solution is analyzed and explained in detail in this article and the corresponding simulations and experimental verifications are performed. According to the obtained results, the proposed power divider has excellent overall performance, in particular low loss, ultrawideband, high isolation, and good amplitude/phase consistency. [ABSTRACT FROM AUTHOR]

Time-frequency synchronization plays an important role in the construction of solar radio telescopes (such as heliograph and interferometry). In the development of a synchronization system, time-frequency signal is divided and transmitted to each antenna in an array, therefore, the performance of the signal splitting devices determines the quantity of the data. To address this situation, we designed a frequency transmitting system, and conducted a test to compare the phase difference among outputs (10 MHz - 1.4 GHz), and the deterioration of the frequency stability (10 MHz - 1GHz) brought by different splitting devices (fiber splitter and power divider). The following results had been obtained: 1) Phase difference introduced by both fiber splitter and power divider can be restricted in a range of ±4°, and the fiber splitter is rather stable, which indicate that a better imaging effect of heliograph can be achieved when using fiber splitters. 2) Frequency stability deterioration get better (worse) with increasing temperature for fiber splitter (power divider) in the testing frequency range for a short-time sampling (100 ms), and for a long-time sampling (10 min), the frequency stability of different devices is determined by both temperature and signal frequency. By estimating the SNR, the performance of optical splitter is found to be slightly better than power splitter. This article provides a basis for the selection and compensation of frequency transfer system components for integrated aperture heliograph, and provide a feasible solution of the construction of low-cost radioheliograph.

A compact broadband balun based on a new planar wideband power divider circuit is presented in this work, which makes use of the substrate integrated waveguide (SIW) technique and multilayer printed circuit board (PCB) process. A broadband 180° reverse-phase characteristic between the two output ports can be easily achieved by the middle metal-ground of the SIW power divider. An elliptic coupling slot is utilized for this multilayer SIW power divider to realize a broad passband. The concept is validated by simulation and measurement. The measured results suggest that a 10 dB return loss at the input can easily be achieved, across a 50.3% relative bandwidth from 11.3 to 18.9 GHz. The measured amplitude and 180° phase imbalance between the two outputs are within 0.35 dB and 1.9°, respectively. [ABSTRACT FROM AUTHOR]

This paper proposes a 7-way microstrip divider for hexagonal honeycomb structures. The honeycomb arrangement has advantages such as equidistant adjacent output ports and high space utilization. The structure comprises six output ports arranged hexagonally and one output port placed at the center of the hexagon in the same plane. To design such a divider considering the output ports' positions, this paper proposes the combination of a microstrip 6:1 unequal Wilkinson divider and a 6-way microstrip divider. To facilitate the implementation of the 6:1 unequal divider, including a transmission line with a high characteristic impedance, a microstrip coupler is used, and for the 6-way microstrip divider, a design scheme and analysis considering the impedance matching and isolation of the output ports are presented. Moreover, the ground layers of the two microstrip dividers are constructed in a back-to-back structure to minimize the size of the overall divider. For validation, a 5.8 GHz 7-way divider is designed, implemented, and measured. The measured S-parameters show that the proposed 7-way divider has appropriate return loss, insertion loss, isolation, and power distribution with a phase difference under 4.7°.

In this paper, an approach to n-stage (n= 3, 4, 5...) balanced-to-single-ended out-of-phase power divider is proposed, which enhances the bandwidths for port matching, isolation and common-mode suppression firstly. Compared with the traditional single-ended multistage power divider, this approach has special circuits (common-mode and isolation circuits) for improving common-mode suppression and isolation, respectively. For common-mode suppression, the 180° microstrip line between the balanced port and the common-mode circuit composed by one parallel open stub are adopted to achieve wideband common-mode suppression. For isolation, the isolation circuits formed by cascade stage structure and parallel resistors are both adopted to improve the isolation bandwidth. The basic analysis at the center frequency is given, and for verifying the theoretical prediction, two prototypes of the 3-and 4-stage power dividers are fabricated and measured, which show 46.7% and 63% 20-dB operating bandwidths, and 0.25 dB and 0.3 dB minimum insertion loss, respectively. These two prototypes present that the 20-dB operating bandwidths are 16.7% and 33% wider than the single-stage balanced-to-single-ended power divider.

A dual-band balanced to unbalanced power divider with independent power division ratios (PDRs) at two operating frequencies is proposed in this article. The proposed power divider includes a dual-band phase inverter, a grounded resistor, and four transmission-line sections (TLS). By simultaneously changing characteristic impedances and electrical lengths of the four TLS, the independent PDRs are obtained, and the large-signal output port at lower and upper operation bands can be different. Compared to the previous works, it has more flexibility in the power division. Moreover, the closed-form design equations are provided and discussed. To verify the proposed structure, two BTU power dividers operating at 1.0 and 2.0 GHz are designed, fabricated, and measured. The PDRs of the first power divider are -6 and 6 dB for the lower and upper operation bands, respectively. The second power divider has the PDRs of 3 and -6 dB. The measured results are good agreements with the theoretical calculation and electromagnetic simulation.

Recently, research has focused on developing efficient wave-guided THz system-on-chip (TSoC) components to reduce physical bulk, loss and cost of free-space THz systems. We recently demonstrated a TSoC platform using a coplanar-stripline (CPS) transmission-line on a 1 μm-thin membrane to generate and detect THz-bandwidth pulses with low loss and low dispersion up to 1.5 THz. In this paper, we demonstrate experimentally an in-phase THz power divider (TPD) at frequency 0.65 THz using the CPS transmission line defined by photolithography on a thin membrane. Measured pulses show close agreement with simulation results. The spectral power density of the measured THz-bandwidth pulses at the output ports are identical at the frequency of 0.65 THz with less than 1 dB power imbalance over a wide spectrum up to 1 THz.

In this article, a novel $n$ -way topology is proposed to design a class of multiway wideband filtering power dividers (FPDs). It consists of $n$ -coupled multimode resonators and $n$ resistors. To achieve a wideband filtering response, the stub-loaded multimode resonator is first employed. A good port–port isolation can then be obtained by electrically connecting the original open end of the two half-wavelength stubs of the two adjacent multimode resonators, and amounting a shunt resistor in-between the two adjacent stubs, which is allocated a quarter-wavelength away from the electrical connection point. The frequency responses of power division and isolation are analyzed based on even–odd mode, aiming to carry out theoretical analysis for wideband $n$ -way power dividers. To verify the proposed design method, a prototype three-way wideband FPD and a four-way wideband FPD are designed and fabricated. The simulated and measured results show a good agreement from each other, thus verifying the feasibility of this proposal. [ABSTRACT FROM AUTHOR]

This paper proposed an integrated conical conformal array antenna (CCAA) for versatile application to the unmanned aerial vehicles. The CCAA consists of five flexible linear gradient subarrays with a uniform circumferential arrangement around the conical surface. It is also embedded with a pyramid reflective back-cavity (PRBC) within the conical carrier. The implementation for the three different elements of the linear gradient subarray toward impedance match and high isolation was investigated, and their identity resonant frequency (9.8 GHz) principle was developed and demonstrated. Furthermore, the PRBC was presented to improve the radiation null of the elements. A numerical 5-bit phase shifter manipulating phase difference of 72° was then combined with an 8-way power divider to obtain a fixed beam with a half power bandwidth (HPBW) of less than 24°, which indicated the backward endfire direction (θ = 180°) in terms of three circumferential arrays (R#X). Finally, the measurements with the aid of the designed phase shifter and power divider (model SHPDW4-040140S) were conducted. The experimental results show one omnidirectional coverage (360°) in the H-plane through the switching working mode of the elements with a wide scanning solid angle (≥72°) when these elements of the subarray hold an identity resonant frequency and exhibit a uniform performance in the point-to-point communication. The measurements of a narrow HPBW of less than 27.5° and the gain over 10.7 dBi in the endfire direction of the three circumferential arrays show great potential in backward blind space detection simultaneously.

This paper presents a novel wide-band filtering three-port coupler with inherent DC-blocking function, which is simply comprised of a power divider with wideband filtering function and a broadband phase shifter with a modified coupled line. For demonstration, a designed prototype operating at 3 GHz is simulated, fabricated, and measured. From the simulated and measured results, the coupler shows a 49% filtering bandwidth with 12-dB return loss and 90° ± 590°phase shifting. The amplitude imbalance between the two output ports is less than 0.5 dB. The all-passband isolation is below -13 dB and the 25.7-dB upper stopband rejection is up to 5.4 GHz. Good agreement between the simulated and measured results validates the proposed idea. Hence, the proposed coupler is well suited for the applications of wideband, filtering, and single-layer circuitry integration.

In this paper, a tri-band impedance transformer (TBIT) using a coupled line and a dual-band to tri-band transformer is proposed, which can transform frequency-dependent complex impedances to a real-value impedance. In order to explain how to determine circuit parameters, closed-form equations are derived in detail. Based on the TBIT, a compact T-junction power divider (TTPD) is designed. This TTPD works at three different frequencies with independent controllable power division ratios. Simple steps to design the TTPD are listed. To demonstrate the validity of the theory, this paper exhibits a prototype operating at 2, 4.4, and 5 GHz with different power division ratios. Moreover, the simulated and measured results prove that this TTPD has the features of tri-band operation, independent controllable power division ratios, enhanced bandwidths, and small size.

A novel compact quasi-planar four-way power divider with a wide isolation bandwidth is proposed in this paper. The signal is fed through the coplanar waveguide and then divided to the four microstrip-line output ports through a metal via. To realize the high output isolation, the multi-layer circuit structure is used. The isolation network is composed of four isolation resistors and a metal via (common node). Equivalent circuits are given to analyze and design the novel power divider. The detailed analyses are given according to the equivalent circuits. A four-way high-isolation power divider with the center frequency of 2.1 GHz is designed and fabricated. The measured 20-dB relative isolation bandwidth between the output ports is about 58%, while 30-dB relative isolation bandwidth between the output ports is about 10%. The measured results agree well with the simulated ones. The total size of the fabricated four-way power divider is 0.17λg × 0.22λg (λg is the wavelength of the center frequency). It shows that the proposed power divider has not only the advantages of high output isolation and compact size but also the advantages of excellent output and input impedance matching and very low insertion loss. The presented power divider can be used in antenna feed, power-combining amplifier, and so on.

In this brief, the design methodology of high- performance lumped-distributed Wilkinson power divider with extremely small chip area is proposed. A parallel capacitor is included at the input port (port 1) to compensate the imaginary part of the input admittance for input matching. A parallel RC network is connected between the output ports (ports 2 and 3) to attain perfect input matching and isolation of the output ports in the odd- and the even-mode excitations. Dual spiral structure with transmission line length of about λ/10 and symmetrical layout is adopted to achieve miniature area and small amplitude imbalance (AI) and phase difference (PD). At 33 GHz, the prototyped power divider achieves S11 of −17.8 dB, S22 and S33 of −22.7 dB, S32 of −34.7 dB, S21 of −4.1 dB, and S31 of −4.07 dB. The corresponding AI is −0.03 dB and PD is −0.08°. The chip area is only 1.2 × 10−4 λ02, one of the smallest normalized chip area ever reported for millimeter-wave (mm-wave) power dividers. The superb results of the power divider indicate that it is suitable for power division/combination in mm-wave transceivers. [ABSTRACT FROM AUTHOR]

When quadrature couplers and power dividers are implemented in integrated circuits, accurate isolation networks can not be realized due to the nonideal resistors and the process variations. We present an isolation network design technique which cancels the resistor parasitic effects and also increases the tolerance to variations in the resistance values. A Lange coupler and a power divider are designed at Ka-band using the proposed accurate and process-tolerant isolation networks. The improvement is analytically shown and empirically verified with our in-house GaN-based microstrip MMIC process. For the coupler, the measured return losses and isolation are better than 20 dB from DC to 40 GHz. The power divider achieves 20 dB return losses and isolation in a fractional bandwidth of 50%. Both devices maintain 20 dB performance even when the variation in sheet resistance is as high as 30%. [ABSTRACT FROM AUTHOR]

In this article, a type of multiport power divider is proposed based on the concept of epsilon-near-zero (ENZ) metamaterials. An arbitrarily shaped ENZ metamaterial comprising a dielectric impurity is connected to $N$ waveguides, and the incident power can be efficiently delivered to output waveguides, with transmitted fields being exactly equal in both amplitude and phase for output branches. Hence, the proposed power divider allows a balanced power allocation independent on its geometrical symmetry. This design philosophy can further be extended to generic dividers with arbitrary power division ratios by modifying the widths of the output waveguides. The experimental verification is carried out in waveguide-emulated ENZ structures. The fabricated eight-way equal-split divider is measured with an average insertion loss of 0.6 dB, a transmission amplitude imbalance of 0.7 dB, and a phase imbalance of 10°, over the 10-dB return-loss bandwidth from 5.35 to 5.56 GHz. The ten-way unequal-split divider with two different groups of outputs is also prototyped, providing a custom-designed power division ratio. [ABSTRACT FROM AUTHOR]

A spiral-coupled-line-based Ka-band (26.5–40 GHz) CMOS Wilkinson power divider with a shunt capacitor (C) at the input and a shunt RC (or C) between the outputs is reported. The spiral coupled line, i.e., two noninverting spiral transmission lines (TLs) with magnetic coupling, has a positive mutual inductance. This leads to a significant TL-length reduction (from about λ/7 to λ/12) for a specific TL series inductance. At 33 GHz, the power divider achieves prominent S11 of −21.5, S22 of −22.1, S33 of −22.1, S32 of −26.1, S21 of −4.063, and S31 of −4.052 dB. The corresponding amplitude imbalance (AI) and phase difference (PD) are −0.011 dB and −0.336°, respectively. Moreover, S11 is smaller than −10 dB for 0–45.3 GHz, corresponding to 137.3% fractional bandwidth (FBW). S32 is smaller than −10 dB for 24.1–40.2 GHz, covering the Ka-band and corresponding to 48.8% FBW. The power divider occupies a normalized area of 1.2 ×10−4λ02, one of the smallest normalized chip areas ever reported for millimeter-wave power dividers. [ABSTRACT FROM AUTHOR]

In this article, a simple and effective method based on the metamaterial concept is proposed to achieve very high isolation between the output ports of a millimeter-wave power divider (MWPD). The proposed MWPD is designed for use in 5G applications (28–32 GHz). In order to increase the isolation, three metamaterial rows are used, each row containing eight proposed unit cells. These metamaterial unit cells are loaded between two dielectric layers. By using this method and without isolating resistors, isolation is improved by more than 36 dB, as compared with a prototype power divider in which no metamaterial element was used. The maximum measured isolation is 43 dB at 30 GHz. The final dimensions of the proposed MWPD are $8 \times 8\,\,\times0.582$ mm3 or $0.9\,\,\lambda _{\mathbf {g}} \times 0.9\,\,\lambda _{\mathbf {g}} \times 0.08\,\,\lambda _{\mathbf {g}}$ where $\lambda _{\mathbf {g}}$ is the guided wavelength at 30 GHz. The simplicity of design, its compactness, and most importantly, high isolation between output ports without any lumped resistor are the key advantages of the proposed MWPD. [ABSTRACT FROM AUTHOR]

A coupled-line based dual-band power divider using substrate integrated suspended line (SISL) for WLAN application is proposed in this brief. Two-section cascaded coupled line in each output path is used for dual-band response. One coupled line loaded at the input port is to improve the frequency selectivity. Two lumped resistors placed between two pairs of the two-section coupled line are used for isolation enhancement. Multi-layer SISL structure is introduced to realize tight broadside coupling, as well as for low loss, miniaturization and self-packaging. To further reduce the dielectric loss, the suspended substrate is cut out in specific pattern. The proposed dual-band power divider (DBPD) is analyzed using the even- /odd- mode method, the S-parameters are derived, and the design procedure is exhibited. For verification, a DBPD prototype working at 2.45 / 5.13 GHz is implemented. The measured results agree well with the simulated ones. The two passbands are from 1.7 GHz to 3.1 GHz and from 4.6 GHz to 5.5 GHz, with fractional bandwidth (FBW) of 58.3% and 17.8%, respectively. The measured return loss and isolation are both better than 15 dB in both passbands. [ABSTRACT FROM AUTHOR]

This article presents a superconducting material based planar broadband 3-way Wilkinson power divider which can be used in the Josephson quantum voltage device for the voltage standards. The 3-way Wilkinson power divider aims to improve the integration of Josephson voltage device compared to the commonly used 2-way power divider. A two-stage λ/4 section on each branch is used to increase the bandwidth, and a π model with lumped equivalent elements are used to further decrease physical dimension in device area. Different from the conventional spatial design of N-way Wilkinson power divider, this work designs a planar broadband 3-way divider to be compatible with the on-chip fabrication process. Simulation results show that the insert loss is below 0.18 dB at working bandwidth of 16.7∼23 GHz, the division imbalance of each branch is below 0.044 dB, and the input and output reflection is better than 15 and 11.9 dB, respectively. The isolation between any of the three output ports is better than 11.8 dB. All these indexes satisfy the requirement of the Josephson voltage standard application. To further prove the validity of our design, real device based on superconducting material is realized and characterized. Devices with a 3-way power divider and three 2-stacked Josephson junction arrays with 256 junctions in each array are fabricated. The experiment results indicate the potential usage of our design in quantum voltage standard devices for high-voltage output. [ABSTRACT FROM AUTHOR]

This article introduces two-way broadband air-filled substrate integrated waveguide (AFSIW) isolated power dividers/combiners based on surface mounted absorbing materials. The proposed structures take advantage of the AFSIW multilayer feature. The absorber implementation is found highly tolerant of variations in dimensions and positioning. Three different power dividers/combiners topologies are analyzed theoretically, simulatively, and experimentally. The measurement results validate the broadband responses of the fabricated Ka-band demonstrators. The proposed power dividers/combiners are intended to exploit high-power AFSIW system on substrate (up to few hundred watts). [ABSTRACT FROM AUTHOR]

This paper presents a novel dual-band filtering balanced-to-unbalanced impedance transforming out-of-phase power divider using a simple admittance inverter with an extreme high frequency ratio and arbitrary power division, which is composed of stepped-impedance transmission lines. Based on the traditional transmission-line theory and ABCD/V matrix, the closed-formed analytical equations and complete design procedure are derived and provided for the filtering differential-mode transmission with high frequency ratio and good dual-band common-mode suppression. For demonstration, a designed prototype operating at 1 and 6.4 GHz are simulated, fabricated, and measured. The measured results agree well with the EM simulation perfectly.

In this paper, a balanced-to-balanced power divider with a wideband filtering function is proposed. The power divider is simply composed of coupled-line sections, λ/4 lines and isolation resistors, and explicit design methodology is given. From the simulated and measured results, the power divider shows 49% differential-mode filtering bandwidth with two additional transmission zeros introduced, and the common-mode transmission is suppressed below -12 dB over 141% frequency bandwidth. This power divider can be a candidate for constructing fully-balanced systems.

A wideband half-mode substrate integrated waveguide (HMSIW) power divider with bandpassfiltering response using the slotline isolation technology is presented in this paper. Resistive slot on the bottom layer is employed to improve the output isolation. To obtain filtering response, L-type slot line and two multimode SIR resonators loaded symmetrically at two sides of the input transmission line are employed to generate transmission zeros at upper stop band. In addition, filtering response is achieved by combining the inherent high-pass characteristic of the HMSIW and the TZs. The equivalent circuits are presented and analyzed by using evenand odd-mode method, and the relative design equations are derived. The measured return loss of the HMSIW power divider is about 10 dB and its isolation is greater than 15 dB from 3.8 to 5.8 GHz. All measured results show reasonable agreement with the simulated ones.

Based on the concept of conventional Gysel power divider, a novel concept of half-mode substrate integrated waveguide (HMSIW) Gysel power divider was reviewed and developed, by simply combining a traditional HMSIW power divider and a microstrip isolation network. The proposed concept was reviewed, investigated, and analyzed thoroughly, after that, Y-type, T-type, and Parallel-type HMSIW Gysel power divider were designed and analyzed, respectively. Furthermore, based on Parallel-type design, a developed version using two isolation networks was proposed for frequency bandwidth enhancement. All the four prototypes were fabricated and measured for verification and comparison. The good electrical performances and compact configuration indicate the advantages of the proposed concept and an excellent candidate for high power-handling HMSIW/SIW circuits or systems.

In a conventional power divider, power dividing network and isolation network are usually independent of each other. To reduce the size of out-of-phase power divider with arbitrary power ratio, coupled microstrip lines are proposed to facilitate power dividing and isolation of a power divider simultaneously in this article. Formulations have been derived for the proposed out-of-phase power divider with arbitrary ratio. Two compact power dividers are implemented on the printed circuit board (PCB) with power ratio $k^{2} = 9$ and $k^{2} = 1000$. It can be observed that there is a satisfactory agreement between the simulated and measured results. [ABSTRACT FROM AUTHOR]

A new power divider is proposed with a compact size. In 50- $\Omega $ systems, impedance transformation is of great importance for power dividers. Coupled microstrip lines with capacitor loaded and two short-circuited ports are introduced to properly transform impedance and increase degrees of freedom in power divider designs. Image impedance and image transfer constant of coupled microstrip lines with capacitor loaded are derived. The main structural parameters of the power divider are calculated accordingly. A special design procedure is illustrated for the proposed power divider with the capacitor loaded, which is implemented on a printed circuit board. A good agreement between the simulated model and the fabricated sample is observed, which demonstrates the validity of the proposed circuit model and the design scenario. [ABSTRACT FROM AUTHOR]

Package-integrated and ultrathin power dividers with footprint smaller than unit $\lambda ~_{0}~^{\mathrm{ 2}}$ at the operating frequency of 28-GHz 5G new radio (NR) n257 and n258 bands are presented for the first time for small-cell applications. These power dividers are also configured as antenna arrays using endfire Yagi–Uda antenna elements. Utilizing minimal matching techniques, two-, three-, and four-element antenna arrays are designed without compromising on the bandwidth of operation or electrical performance. These thin-film power dividers exhibit a cross-sectional height of $147~\mu \text{m}$ and can be implemented in the top metal layer of front-end module packages. Panel-compatible semiadditive patterning (SAP) process is utilized to realize these structures, which yields precise line space dimensions required for millimeter-wave (mm-wave) applications. This results in power dividers with low added insertion loss, low VSWR, and minimal phase difference between output ports. The added insertion loss is 25% less than similar structures reported on integrated fan-out architectures. The antenna arrays exhibit high gain and efficiency. Excellent model-to-hardware correlation is observed with multiple coupons of the same structure. Package-integrated power dividers and antenna arrays based on ultrathin laminated glass substrate represent a major step toward realizing compact mm-wave antenna-in-package for 5G small-cell applications. [ABSTRACT FROM AUTHOR]

This article demonstrates the feasibility of a novel waveguide dual-mode two-way power divider that is based on an evolved junction having a dedicated T-shaped central matching element (scatterer). This scatterer, with matching sections facing all three ports, provides equal power division and routes the two TE10/TE01 orthogonal modes of a square waveguide toward the corresponding output ports. The proposed design is compact, easily scalable and can be cascaded to obtain $2^{N}$ output ports, being $N$ the number of division stages. Moreover, this structure represents the first waveguide dual-mode two-way reactive power divider (three physical ports) reported in the scientific literature. An exemplary has been manufactured showing an 11% relative bandwidth at 12 GHz and less than −50 dB of cross-coupling. Transmission loss and isolation between output ports are in good agreement with electromagnetic (EM) simulations. [ABSTRACT FROM AUTHOR]

We present the design and analysis of coupled-line-based Ka-band CMOS power dividers. A single spiral structure with a symmetrical layout is adopted to achieve a miniature area and small amplitude imbalance (AI) and phase difference (PD) performance. The first divider (divider-1) achieves ${S} _{21}$ and ${S} _{31}$ of −4.029 and −4.008 dB, respectively, at 33 GHz. The corresponding AI and PD are −0.021 dB and 0.369°, respectively. Moreover, the second divider (divider-2) achieves ${S} _{21}$ and ${S} _{31}$ of −4.093 and −4.055 dB, respectively, at 33 GHz. The corresponding AI and PD are −0.038 dB and 0.148°, respectively. The chip area is $1.7\times 10^{-4} \lambda _{0}^{2}$ , one of the smallest normalized chip area ever reported for millimeter-wave (mm-wave) dividers. The prominent results of the dividers indicate that they are suitable for power division/combination in mm-wave transceivers. [ABSTRACT FROM AUTHOR]

In this article, a miniaturized dual-band dual-polarized slot antenna array is proposed for base station applications. It consists of two closely located $1 \times 4$ subarrays for the digital cellular system (DCS) and wideband code division multiple access (WCDMA) operations. The band-notched slot antenna (BNSA) is designed and adopted as the subarray element with radiation-suppression characteristic at notch frequencies. The notch frequency for one subarray is designed at the center operating frequency of the other subarray. As a result, the radiation from DCS subarray could be effectively suppressed within the WCDMA band and vice versa, resulting in high isolation between two subarrays with a small separation distance. By using the artificial magnetic conductor (AMC) reflector, the array height could be reduced by half, as compared with the perfect electric conductor (PEC) counterpart. In addition, a four-way unequal power divider is designed for the array’s beam-pattern synthesis. For the demonstration, the proposed array is fabricated and measured. The measurement results show that the dual-band array achieves the impedance bandwidths of 1.65–1.88 and 1.89–2.22 GHz, the isolations over 25 dB, the realized boresight gains of 12.2–12.8 and 12.3–13.2 dBi, and the sidelobe levels below −18 dB. The results indicate that the proposed array is a promising candidate for base-station applications. [ABSTRACT FROM AUTHOR]

In this paper, a simple and compact planar balanced-to-unbalanced in-phase power divider with arbitrary terminated impedances is proposed based on the coupled-line structure and a single grounded resistor. By using the even-/odd-mode analysis and the traditional transmission-line theory, the complete design procedure and analytical equations are obtained to achieve good performances for differential-mode transmission, common-mode suppression, phase difference, arbitrary terminated impedances, and isolation. For demonstration, two different prototypes with 50-to-50 Ω matching and complex impedance transformation are designed, fabricated, and measured. Good agreement can be observed between simulated and measured results.

A new method to design wideband differentially driven dual-polarized antenna with high common-mode suppression and high port isolation is presented. The presented antenna can be equivalent as a combination of a six-port power divider and four crossed folded dipoles. The six-port power divider is composed of two orthogonal input ports and four equal magnitude output ports. Detailed analysis illustrates that the six-port power divider can have wide bandwidth and high isolation under odd-mode excitation and high common-mode suppression under even-mode excitation. Therefore, based on the wideband and high even-mode suppressed six-port power divider, a wideband differentially driven dual-polarized antenna is developed with high common-mode suppression. To validate the design concept, the proposed antenna was designed, fabricated, and measured. The measured results prove that the antenna has a wide impedance bandwidth of 1.64–3.0 GHz (58.6%) for the return loss higher than 15 dB and isolation higher than 35.4 dB. In addition, very high common-mode suppression is achieved for the measured common-mode reflection coefficient higher than −0.87 dB over the entire bandwidth. With stable antenna gain and half-power beamwidth, the developed antenna is suitable for base station applications. [ABSTRACT FROM AUTHOR]

In this article, a vertical four-way rectangular waveguide to microstrip power divider is proposed. The power divider achieves perfect power division from 10.1 to 11 GHz with a 20-dB return loss and a short longitudinal length. Based on the four-way power divider, two microstrip ports are added, and a compact improved four-way rectangular waveguide to microstrip power divider is constructed. The 20-dB return loss bandwidth of the power divider can be extended from 9.9 to 12.4 GHz. If all the output microstrip ports are connected to resistive loads, the power dividers become rectangular matching terminations. Thus, the four-way power divider can achieve a rectangular matching load with an 8% bandwidth and a 2-mm matching length. The improved four-way power divider can achieve a rectangular matching load with a 22.4% bandwidth and a 2.5-mm matching length. The measurements agree well with the simulations. The proposed designs of the rectangular loads are superior in their compact volume, high power capacity, and ease of fabrication. [ABSTRACT FROM AUTHOR]

In this communication, a substrate integrated wave (SIW) cavity is applied in feeding dielectric resonator antennas (DRAs) and designing reconfigurable circuits for multifunction applications. The TE120 mode of the SIW cavity is utilized to differentially feed a dielectric resonator (DR) for high-performance antennas with low cross-polarization and symmetrical patterns. The TE110 mode is used to design a filter or a power divider with continuously tunable operating frequency. Considering the characteristics of the field distributions, the filter or power divider part shows no effect on the antenna part, meaning that different functions are independent. The proposed multifunction applications of the SIW cavity are listed, simulated, and verified by experiments. [ABSTRACT FROM AUTHOR]

A new class of in-phase and out-of-phase power dividers with constant equal-ripple frequency response and wide operating bandwidth is presented in this paper. The proposed design is based on microstrip-to-slotline transitions and slotline resonators. A slotted T-junction is adopted to split the power into two parts and obtain wideband isolation between the two output signals at the same time. The characteristic impedance of the transitions and resonators determines the operating bandwidth and in-band magnitude response. By reversing the placement direction of the slotline-to-microstrip transition, the electrical field is reversed, thus resulting in out-of-phase responses between output ports. A thorough analysis of the relations between the structure and the characteristic functions is provided to guide the selection of parameters of the structure in order to meet the design objectives. In the structure, simulation and measurement are conducted to verify the design method. For both in-phase and out-of-phase cases, more than 110% bandwidth has been achieved with excellent matching at all ports and isolation of output signals. Constant in-band ripple is obtained within the operating band of the power dividers, indicating that the proposed design can realise minimal power deviations, which is extremely desired in wireless systems. [ABSTRACT FROM AUTHOR]

A new vertical guiding structure in low-temperature cofired ceramics (LTCC) substrates is proposed. This vertical LTCC integrated waveguide (V-LIW) allows transmitting signals and realizing components in the body of the LTCC substrate perpendicular to its surface. This vertical integration leads to considerable footprint reduction while opening the door to higher frequency coverage as well as easy implementation of $E$ -plane structures. Discontinuities in V-LIW and transitions between the proposed V-LIW and conventional horizontal guiding structures such as coplanar waveguides, standard rectangular waveguides, and substrate integrated waveguides are also introduced. Applications to the design of V-band and W-band filters, couplers, and power dividers are presented. Several prototypes are fabricated with measurement results showing a good agreement with simulation data. [ABSTRACT FROM AUTHOR]